Drugs are used in medicine to alleviate pain, treat illnesses, and modify or manipulate a patient's physiological systems. For quality control, which is a collection of procedures used to guarantee that pharmaceuticals and other goods are produced in a way that always satisfies requirements for identity, content, and purity, among other things, drug analysis is crucial. This makes the study of pharmacological chemicals and their potential use in clinical analysis extremely related, particularly in the field of health [1]. Drug improvement, monitoring, and patient consumption all depend on drug analysis. Subsequently, it's critical to generate analytical techniques that can recognize pharmaceuticals in a variety of sample matrices both quantitatively and qualitatively. Drug analysis is normally carried out using traditional instrumental analytical techniques such (MS) mass spectrometry, (CE) capillary electrophoresis, (GC) gas chromatography, and (HPLC) high-performance liquid chromatography (HPLC). Conversely, these methods are only suitable for routine analysis in a central laboratory since they demand expensive equipment, detailed sample preparation, and highly skilled operators. The use of nanosensor devices as analytical tools has become more popular and has impacted numerous industries, including pharmaceutics and medicine. Related to standard instrumental methods, miniature analytical methods have a number of profits, including cheap costs, quick analysis, minute reagent and sample intake, high throughput analysis, portability, and robotics [2].

Drug testing services, drug checking services, customs services, and law enforcement firms all analyze drug substances. A growing amount of information on the drug material will be provided to the analyst by each evaluation, identification, and/or quantification approach, depending on the goal and scope of the test. While gas chromatography, mass spectrometry is usually employed for drug identification and confirmation, color tests are still the most often used screening method for evaluating confiscated material in forensic drug laboratories. Analytical methods such as infrared spectroscopy, mass spectrometry, nuclear magnetic resonance (NMR) spectroscopy, Raman spectroscopy, and X-ray diffractometry that can yield structural information offer the highest degree of selectivity [3].

1.1 Limitations of Conventional Methods

These conventional methods of drug analysis faces some challenges such as  lack of sensitivity ,low specificity and time consuming procedures that emphasize  the need for novel strategies to get over these obstacles and improve drug analysis's precision and effectiveness, including nanosensors. In these conventional methods, only volatile chemicals are separated, repeated heating causing the stationary phase to disappear, stress if the concentration of the sample chemicals is very high. Hence, separation challenges .

Fig.1 Demonstrates the few limitations of conventional methods.

1.2 Nanosensors as a Promising Resolution

To gain a deeper comprehension of the special qualities of nanosensors, in 1959, Richard Feynman proposed the idea of nanotechnology. However, the field of nanotechnology began in 1981 when an atomic cluster was observed using scanning tunneling microscopy for the first time. In 1993, nanosensors became the world's first commercially available scanning probe microscope (SPM) and atomic force microscope (AFM) probes. The invention and use of batch processing in the production of AFM probes has aided in the high tech sector's adoption of the atomic force microscope. There have been various successful developments of nanomaterials with enhanced electrical, optical, mechanical, and electrochemical sensitivity since the invention of nano technological instruments. In many label-free detection applications, nanosensors can be used to offer an excellent proportion of signal to noise regardless of very low substrate concentrations. Though definitions vary, most define a "nanosensor" as a sensing device having at least one dimension thinner than 100 nm that gathers data at the nanoscale and transforms it into data suitable for study.Because nanosensors can be used as instruments for other nanoproducts, such as semiconductors or nanoscale machinery [4].

Over the past few decades, the global market for nanosensors has experienced growth. Innovative applications of nanosensors in medical diagnostics and other devices have been witnessed in the market. It can be applied broadly and is also utilized in the design of the structures. This aids in the monitoring of several contaminants and environmental chemists using more economical, effective, and focused nanomaterials. Furthermore, a chemical sensor's larger surface area denotes improved exposure to and detection of the target molecule at low concentrations. Extreme levels are caused by nanoparticles' delicate structure. Their larger surface area makes them more resilient and efficient. Certain nanoparticles, like those of silver, platinum, and palladium, are used in nanosensor technology. Nanomaterials are also easily manipulated; their composition, size, and structure, all influence and combine the properties of these variables. Nanosensors are widely used on the devices that surround us and have undergone thorough testing as a component of our civilization [5].

A nanosensor is a sensing device that has at least one dimension of 100 nm that is used to collect data for analysis and information on the nanoscale. The physical and chemical characteristics of materials at the nanoscale, which are frequently different from their bulk characteristics, are the focus of nanotechnology. These phenomena can be exploited by nanosensors. By utilizing these extraordinary properties of nanosensors, sensors that are conventionally developed with fewer sensing elements and/or nanosensors can be enhanced. Because of this, nanosensors may be larger devices that utilize the properties of nanomaterials to detect and measure events at the nanoscale rather than being small enough to do so. New generations of technologies can be developed thanks to nanosensors. They may readily interact with substances at the nanoscale (such proteins, for example) and identify special processes that are invisible at the macroscale. These days, a variety of techniques, including as molecular self-assembly, bottom-up assembly, and top-down lithography, have been proposed for creating nanosensors [5].

Outstanding magnetic, electrical, optical, mechanical, and catalytic capabilities that differ significantly from their bulk counterparts can be created in nanomaterials. It is possible to accurately manage the size, shape, synthesis conditions, and appropriate functionalization of nanomaterials to get desired characteristics tuning [6].

2.1 Nanosensors Operational Principle

 Single molecules can be measured with a nanosensor. The components of a nanosensor are a transducer, detector, analyte, and sensor. Nanosensors typically monitor electrical changes in the materials that make up the sensor. Analyte diffusing from the solution to the sensor surface causes a targeted and effective reaction that changes the transducer surface's physicochemical characteristics. This, in turn, modifies the transducer surface's optical or electronic characteristics, producing an electrical signal that can be detected. Selective detection of several analytes is possible using nanosensors. While single sensors are limited to detecting a single type of analyte, multiplex sensors are capable of detecting many types of analytes. Selectivity and specificity of a nanosensor are revealed by its recognition element. The design of nanosensors has made use of a wide range of recognition elements, such as enzymes, aptamers, antibodies, and some functional proteins. Aptamers and antibodies are the most often used recognition elements in nanosensors [7]. Basic components of nanosensors are shown in fig 2.

Fig 2: Components of Nanosensor.

2.2 Types of Nanosensors

As shown in table 1 nanosensors can be categorized based on its applications, structure, and energy source.

1. Based on the energy source, the nanosensors are categorized as (i) active nanosensors, which require an energy source, like a thermistor, and (ii) passive nanosensors, which don't require an energy source, like a thermocouple and piezoelectric sensor.
2. Structure-based classification: There are four different categories of sensors that are based on structure: (i) optical nanosensors; (ii) electromagnetic nanosensors; and (iii) mechanical or vibrational nanosensors.
3. Application-based categorization: Based on their intended use, four different types of sensors have been identified: chemical sensors, deployable nanosensors, electrometers, and biosensors [8]

Table 1. Nanosensor Classification from ref. [8] available under  an open access  (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/).

Types of nanosensors used in drug analysis are defined below:

2.2.1 Chemical Nanosensors: Sensors are analytical tools that react to the concentration or activity of a chemical agent in a sample in a selective and reversible manner. Chemical sensors are typically utilized to determine the problematic analytes in a qualitative or quantitative manner. In theory, a straight forward chemical or physical contact causes the surface of the chemical sensor to detect the analyte. An apparatus known as a transducer transforms this interaction into a constant electrical signal that is measurable. Analyte concentration in the sample is reflected in the output signal. As per the definition provided, a chemical sensor is a device that produces an electrical signal based on the chemical composition or concentration of an analyte molecule. An ideal chemical sensor should be inexpensive, simple, reliable, and tiny in size.  Chemical sensors track the activity or concentration of the corresponding chemical species in the gas or liquid phase in numerous analytical procedures. Chemical sensors are thus used in continuous chemical analysis applications such as food and medication analysis, environmental pollution monitoring, and clinical diagnostics [9].

2.2.2 Fluorescent Nanosensors: Biological, pharmacological, and chemical substances can be qualitatively and quantitatively analyzed using fluorescence analysis with fluorescent nanosensors. Because they are more affordable, easier to use, and sensitive than other analytical instruments methods including gas chromatography, high-performance liquid chromatography, and capillary electrophoresis, fluorescence-based nanosensors are preferable to them. The basis for fluorescent probes includes organic compounds, rare earth metals, fluorescent dyes, fluorescent polymers, and fluorescent  nanocarriers . Quantum dots (QDs) and carbon dots (CDs) are two of the most widely used fluorescent nanosensors . Due to their unique qualities, which include high chemical inertia, steady illumination, minimal toxicity, and biocompatibility, a new kind of illuminating carbon nanoparticles called CDs has recently been produced and attracted a lot of attention. With these characteristics, CDs are an excellent choice for creating novel, highly sensitive sensors. The vital role that ions play in life and health processes makes fluorescent CDs with responsive ion properties which allow them to respond selectively to particular ions extremely valuable among intelligent sensors. These eco-friendly, biodegradable nanosensors work theranostically to combat a variety of infectious illnesses and malignancies. Fluorescence technologies are used for biomedical imaging and bioanalysis because of their ease of use, high sensitivity, and quick reaction in detecting tiny levels of analytes [10].

2.2.3 Plasmonic Nanosensors: Plasmonic-based nanosensors are the most effective tools for detecting and measuring molecular analytes at lower concentration levels because of their very sensitive detection, label-free, real-time sensing process and ease of use. Additionally, plasmonic sensors have the potential to sense in many other fields, such as biosensors , pharmaceuticals,  environmental monitoring ,food control , homeland security , and environmental monitoring . More attention has recently been paid to sensing technologies with the goal of improving sensitivity and detection limit, especially with regard to lower concentration chemicals in biosystems. To create these plasmonic sensors, a variety of materials have been used in their design. The performance of the sensor system is determined by the material choices. Scientists are now interested in using plasmonic nano-scaled materials to create plasmonic nanosensors. This is due of its excellent thermal, optical, chemical, mechanical, electrical, and electrical properties. A viable substitute technique for pharmacological and biological analysis is the integration of plasmonic-based sensing [11].

2.2.4 Electrochemical Sensors: Electrochemical sensors are apparatuses that facilitate the acquisition and conversion of chemical data, such as proton or electron transfer, into a signal that can be utilized for analysis, like a variation in potential or current. Electrochemical sensors work primarily through the connection between the detecting materials (modifier) and the analyte, as well as the element's capacity to convert the energy levels of the chemical signal generated by this contact into a measurable signal. Next, the material selection for the electrode is crucial since it needs to have the right electrochemical properties and work well for immobilizing the converter on the electrode surface. Gold, platinum, carbon paste, glassy carbon, were among the materials that were commonly employed. Because of the benefits that carbon nanomaterials offer such as their comparatively low budget, broad potential comeback window, chemical and physical properties, and variants in conductivity they have also garnered attention in the development of electrochemical sensors [1]

2.2.5 Biosensors: A biosensor is a device that primarily employs electrical, thermal, and optical signals to detect chemical molecules. These signals are typically produced by particular biochemical events that are mediated by tissues, organelles, immune systems, and whole cells. It consists of a transducer, a compartment for data analysis, an indicator that shows the signal, and an element to identify the target analyte. In order to immobilize the marker, biomarker, or analyte onto the surface of the transducer, the recognition element can be biomolecules such as enzymes, deoxyribonucleic acid, aptamers, antibodies, or fungal spore-binding peptide. A measurable signal is produced by the transducer and recognition element in conjunction High sensitivity and extremely high selectivity are achieved when the transducer moves the signal from the physical or biochemical output domain of the recognition system to the electrical output domain [12].

2.2.6 Naosensors based on Carbon: Because of their vast surface area, size at the nanoscale, and superior strength, flexibility, and electrical conductivity, nanomaterials especially those generated from carbon have extraordinary physical and chemical properties. Their reactivity and optical qualities are determined by their size, shape, and structure. Additionally, it has been shown that functionalization inhibits the agglomeration of nano materials, resulting in synergistic improvements in the mechanical, chemical, and physical properties of the resultant composites [13]. This included recent developments and uses of chemically improved electrodes with carbon nanomaterial for analysis and recognition of drugs and compounds of medical interest, which are crucial for the suggestion of effective diagnoses and for quality control studies in order to protect human health. These applications took into consideration the various carbon nanostructures that were extensively used in the production of electrochemical sensors and biosensors [1].

The current focus of advanced materials research is on the creation and design of nanosensors, which has enormous potential for the establishment of multiple applications in a wide range of many fields. From a practical perspective, nanosensors are typically composed of at least one nanoscale component and are categorized into two categories: chemical or physical. Advanced nanoscale materials-based new technologies offer significant advantages over conventional sensors. In many different and complex contexts, single viruses, proteins, and molecules can all be detected in varying concentrations by nanosensors, which are often quite sensitive. Although creating nanosensors is quite difficult, research and development has made great strides, especially in terms of tailoring production techniques to particular uses. Nanosensors come in a wide variety, as do the methods for producing them [14]. Important restrictions on the synthesis of nanomaterials, such as size, shape, and composition of tuneable quantum dots, are carefully considered. These include reaction temperature, duration, solution pH, and capping ligand. The adjustment of key sensor parameters, such as selectivity, sensibility, stability, low detection limit, reaction time, and recovery time, is covered in detail. Additionally, the potential applications of innovative and untested nanomaterials for sensors are examined, along with new methods for nanoscaled analyte detection and sensing using inexpensive, readily available nanomaterials [15].

3.1 Nanomaterial

A substance is considered a nanomaterial if it is reduced in composition to a nanoscale (1–100 nm) or if it has at least one dimension in a three-dimensional space. The two main categories of nanomaterials are nanostructured material and nanostructured constituents. Its structural proportions in nanostructured materials are on nanoscale. One structural element of a nanostructured element must have at least one outside dimension in the nanometer range. In contrast to conventional materials, nanomaterials offer special qualities. The first artificially produced nanoparticles are metal nanoparticles. Nanometal materials have been studied extensively since they have taken longer to create than other nanomaterials [16].

3.1.1 Nanomaterial’s Taxonomy

On the basis of their morphology, size, shape, content, homogeneity, and aggregation, NPs are frequently categorized. Three different NP morphologies have recently been discovered: spherical, flat and crystalline. Based on the dimension of electron transport, NPs are further divided into four types: zero dimension; 1D, which consists of thin films mostly operated in sensor mechanisms and automated devices; 2D, which consists of next-generation NPs such carbon nanotubes, which offer high stability and absorption; and 3D, which consists of the dendrimers and quantum dots. These are further divided into organic, carbon-based NPs (fullerenes), and inorganic NPs depending on their chemical structures [17].

Fig.3 Illustrating various classes of NMs based on dimensionality.

Generally speaking, nanoparticles and nanoclusters are different. When discussing larger clusters with dimensions ranging from several hundred to several thousand nanometers, the word "nanoparticle" is frequently employed instead. Synthetic nanoscale crystals known as quantum dots (QDs) have a range of characteristics based on their composition and structure. They are capable of transferring electrons. Due to their semiconductor nature, they release certain colors when exposed to UV light. The literature refers to these nanostructures as zero-dimensional nanostructures (0D) .Their distinct physical characteristics enable them to absorb solar light at a significantly faster rate. Quantum confinement in semiconductor particles, surface plasma resonance in certain metal nanoparticles, and other size-dependent features change chemical reactivity that might be applied to the creation of images in photography. One-dimensional nanostructures (one no-nanometer size and two unique dimensions between one and 100 nm) are called one-dimensional nanostructures (1D).
One-dimensional examples of these materials are nanotubes, nanofibers, and nanowires. Indeed, a nanowire or nanotube's length could be substantially longer than 100 nm. Two-dimensional complex substances (2D) are materials made up of thin layers that can include many atoms on their surface and have a thickness of at least one atomic layer. Given their larger dimensions on the macroscale and nanoscale and their low thickness, 2D nanomaterials ought to be the thinnest of all nanomaterials. Generally known as Three-dimensional nanostructures (3D) are bulk materials with all dimensions greater than 100 nm. This dimensionality is demonstrated by materials with a nanocrystalline structure or by characteristics present at the nanoscale.

The formation of bulk nanomaterials can be achieved through the assembly of several nanoscale crystal groups, which are typically oriented differently. More intricate configurations are conceivable for 3D nanomaterials, which can consist of dispersions of nanoparticles, bundles of nanowires and nanotubes, and multi Nano layers [18].

3.2 Nanofabrication

 Nanoparticle synthesis can be achieved by a variety of methods, divided into two categories: top-down and bottom-up methods. Depending on the course of events, response state, and procedures used, approaches are classified into several subclasses. To produce NPs with controlled sizes and appropriate properties for various applications, two distinct approaches are taken into consideration.

3.2.1 Top- Down Fabrication Method

In the top-down (physical) approach, the bulk material is reduced to nanosized dimensions using grinding, cutting, and scratching procedures; in other words, NMs are created from larger/bulk materials without atomic-level control. Therefore, a metal bit is utilized for the physical growth of NPs through the mechanical breakdown of the broad metal structure; this is a well-known to be an affordable, energy-intensive, and long-lasting method. The fact that it cannot regulate the size of the NPs' particles is its main drawback. Consequently, the bulk complement is used first in the top-down technique and then progressively seeps out, forming very little NPs.

3.2.2 Bottom- Up Fabrication Method

Atoms, molecules, or aggregates are the sources of the accumulation of nanoparticles (NPs) in the bottom-up (chemical-based and biological) approach. To build a broad Aggregation of molecules or atoms is the technique used for a variety of NPs. It does offer total control over the size of the particles. Sol-gel handling, chemical reduction, green synthesis, CVD, and other processes are a few examples of this methodology [19].

3.3 Nanomaterials used to Create Nanaosensors

Nanoparticles can be operated as therapeutic agents or as carriers for the move of medications, genetic material, or growth factors (GFs) as of their size and surface chemistry [20].

3.3.1 Metal Nanomaterial:

Metals chemical and physical characteristics differ significantly at the nanoscale from those of the bulk substance. The large surface area to volume ratio intrinsic to nanomaterials, together with the effects of size and shape, are the main causes of this [21].

Gold Nanoparticles (AuNPs) - Because of their mechanical, electrical, thermal, chemical, and optical qualities, gold nanoparticles are one type of nanomaterial that has attracted a lot of interest in the field of biomedicine. Their possible applications include medication administration, gene therapy, photothermal and radiotherapy, biosensing, diagnostic tracers, immobilization of enzymes, and cell imaging [22] . They are widely used in nanosensors.

Silver Nanoparticles (AgNPs) - Silver nanoparticles (AgNPs) have been extensively used to enhance photocatalytic degradation, thermal responsiveness, electro-conductivity, and antibiofouling properties of membranes [23].

Platinum Nanoparticles - Pt nanoparticles outperform the other metallic nanoparticles in biological, biosensor, electroanalytical, and analytical methods, catalysis, and electrochemical sensing reactions  [24].

3.3.2 Carbon-Based Nanoparticles:

A growing amount of research interest has been drawn to carbon-based nanomaterials (such as graphene, carbon nanotubes/nanofibers, carbon nanodiamonds, and carbon nanodots) because of their unique chemical and physical properties. Many of the remarkable qualities of carbon nanomaterials make them perfect transducers in the creation of nanosensors for the detection of various analytes, such as heavy metal ions, food flavors, antibodies, gas molecules and toxic pesticides, in the fields of healthcare, food safety control, and environmental monitoring [25]. Graphene Quantum dots - Carbon-based nanoscale particles known as graphene quantum dots, or GQDs, have exceptional physical, chemical, and biological characteristics that make them ideal for a variety of uses in nanomedicine. Because of their distinct electronic structure, graphene quantum dots (GQDs) have the ability to absorb incident radiation, which can be used in photothermal and photodynamic therapy, which kills cancer, strong and adjustable photoluminescence for use in fluorescence biological imaging and biosensing, and a large carrying capacity of aromatic substances for small-molecule drug delivery [26].

3.3.3 Metal Oxide Nanomaterials:

Nanozymes based on metals and metal oxides that possess notable characteristics have been extensively utilized for various analytical objectives. There are two categories for the principle detection: Two processes occur when the target either activates or disables a reaction within the agent and the nanozyme. Secondly, the amount of target is indirectly indicated by the presence of the nanozyme and the interaction it has with the agent. As per earlier publications, these nanozymes can be applied to detect a range of significant targets, including metal ions, tiny biomolecules, and tumor indicators [27].

3.3.4 Polymeric Nanoparticles:

One particularly useful technique for enhancing medication bioavailability or targeted distribution at the site of action is polymeric nanoparticles. Polymers are theoretically perfect for meeting the needs of every specific drug-delivery system because of their versatility. Polymeric Nanoparticles Based on Gold used for the Diagnosis of Cancer [28]. Since they have excellent sensitivity, selectivity, and adaptability, numerous types of nanosensors are frequently used in drug analysis. The following nanosensor categories are the most significant ones utilized in drug analysis:

Among the many additional phenomena that biosensors are used to examine include cell physiology, cell structure, the impact of drug chemicals on cells, and more. Biosensors are analytical instruments that are utilized to identify the presence as well as the amount of analytes. Hence, in order to identify even the slightest variation in the target analyte's concentration, biosensors are engineered in accordance with the target and transducer process. Furthermore, the target must be distinguished from non-specific particles in the detecting solution by the biosensors. Metrics such as selectivity, sensitivity, detection range, limit of detection, and reuse capacity are used to assess the analytical efficiency of biosensors. To improve biosensor performance and lessen sensing matrix interference, several nanomaterials with varying sizes, shapes, and characteristics have been employed, including polymers, carbon nanomaterials, metallic nanomaterials, quantum dots, and others [29]. When it comes to using nanomaterials to create cutting-edge biosensors, the majority of recent developments have involved the usage of nanotubes, nanoparticles, nanowires, and nanorods [30]. For a variety of reasons, nanostructures are used in the construction of biosensors today, and this has produced significant advancements in the field. By increasing the level necessary to stabilize biomaterials, nanomaterials are used in biosensor structures to boost sensitivity, catalysis, low-potential reactions, and the speedy migration of electrons from the enzyme's active reaction site to the surface of the electrode. This is crucial for the development of third-generation biosensors since the use of nanomaterials in biosensor structures can simplify devices by removing chemical intermediaries of electron transfer. The surface adhesion of biomolecules is significantly facilitated by nanoparticles because of their high free surface energy and large specific surface area [31].

4.1   Biosensor's Operational Concept

A sensor's unique responding location may react to a particular kind of analyte present in the medium. The transformation of information into an electrical signal is started at the site by a chemical reaction that is triggered by an analyte or stimulus. After that, an electrical signal is sent to a different unit the processing unit which proceeds with the detection response. In technical terms, the sensor consists of two components: the transducer and the receptor. Transducer converts electrical energy from a physical or chemical stimulus into a useful analytical signal that can be further examined and displayed electronically. Receptors accept physical or chemical stimuli and convert them into electrical signal which can be detected [32].

Fig.5 Fundamentals of a Biosensor.

4.2 Advantages of Nano Biosensors

Nanobiosensors, or biosensors that use nanostructures, are highly sensitive and efficient because of their broad range of sample stability. Conversely, electron-transfer-based electrochemical methods facilitate the simple and affordable measurement of analytes [31]. In addition to detecting the presence of microbial infections in our bodies, food, water that we consume, and the atmosphere, nanobiosensors can be utilized for the early diagnosis of severe diseases like cancer, which can significantly lower the death rate from cancer. Precision farming using nanobiosensors holds the potential to decrease the overuse of harmful agrochemicals. The consumer can be alerted immediately to any spoiled food by using these sensors in smart food packaging [33]. These sensors' selectivity, linearity, stability, sensitivity, and repeatability all contribute to their applications and utility [34].

 4.2.1    Sensitivity; for very sensitive and precise targeted molecule detection, these sensors usually combine nanomaterials (like gold nanoparticles and carbon nanotubes) with biomolecules (like aptamers and antibodies). Early disease detection and treatment are facilitated by this kind of nanobiosensor, which delivers fast and reliable information [35].

4.2.2 Real Time Monitor; Certain analytical nanobiosensors are useful as practical, real-time monitoring  of various analytes and diseases [36].

4.2.3 Capabilities for Multiplexing; Numerous varieties of nanomaterial-based biosensors can be used to address the multiplexing idea, which allows for the detection of numerous analytes in a single sample. As one of the most popular options for various multiplex systems, quantum dots are photoluminescent nanoparticles that are commonly used [37].

4.2.4 Compatibility with Biological Systems; The size effect, electrical and optical characteristics, and benefits of nanomaterials in the field of biosensing can all be used to effectively increase the sensitivity and lower the detection limit of biosensors. The nanomaterial demonstrates biocompatibility by utilizing nanobiosensors such graphene, quantum dots (QDs), gold nanoparticles (AuNPs), carbon nanotubes (CNTs) and magnetic nanobeads [38].

4.2.5 Efficiency in Terms of Cost; When working with biological materials, it is preferable to use affordable disposable biosensor chips as they reduce the risk of cross-contamination and require less time and effort to clean [39]. Biosensors can be generated in huge quantities, can be downsized for effective use, are readily disposable, environmentally friendly, selective, dependable, and capable of detecting extremely small volumes of target analyte [40]. Biosensors helps in Fast and large-volume detection, Decreased material requirements for fabrication and simplified recycling [41].

An instrument called a sensor is used to measure an analyte, or test component, directly from a sample. A device of this kind should ideally be able to respond continuously, reversibly, and without causing any harm to the sample. The degree of sensitivity of the system is greatly enhanced by the introduction of nanoparticles. A biological component (such as a DNA strand, enzyme, antibody or whole cell) is the component of the system that attaches to the analyte in biosensors in order to precisely detect it. Tiny biosensors as a transducer, the electrode serves as an electrochemical sensor, which uses an organic element as an indicator component. The gap at the nanoscale that exists in between the converter and the receptor in our bodies is typically filled by using nanostructures in these systems [31]. The concept of describing a biosensor's components and the method of combining a transducer device with a bioreceptor were first outlined by Leland Charles Clark Jr. in 1962 [42]. The analytical tools known as biosensors allow chemical interactions to be sensed and translated into an electrical signal that can be detected. Biosensors are devices that combine biological elements like enzymes, metabolites, DNA, RNA, cells, and oligonucleotides with transducers, such as optical, piezoelectric, acoustic, and calorimetric ones. The primary advantage of biosensors is their capacity to transform biological interactions into an electronic form that can be observed and measured. Biosensors are used in medicine to precisely and accurately detect viruses, poisons, tumors, and biomarkers to determine the early signs of a variety of illnesses. Biosensors are becoming more and more important because of their inexpensive cost of production, quick reaction time, mobility, high specificity, and specificity in measuring biological constituents at very small scales [43].

Fig.6 Basic components of Nanobiosensor.

On the basis of their size, shape, and structure, nanoparticles can be categorized into several types. Because of their huge surface area and their nanoscale size, NPs have irreplaceable physical and chemical features. By using nanoparticles, a sensor's sensitivity is increased. The lowest limit of detection (LOD) for the H7 subtype Influenza A virus, for instance, is 10ng/ml, while the LSPR-induced immunofluorescence nanobiosensor has a LOD of 0.4 pg/ml. Its structure, size, and form all contribute to their toughness and responsiveness. Nanosensors come in a variety of forms. In order to provide high sensitivity, affinity-based nanobiosensors communicate with receptors that include ssDNA, antigens, and aptamers. They also interact with nanoparticles  [44].

Transducers, amplifiers, and bioreceptors come together to form biosensors, which are incredibly adaptable analytical instruments that can identify a broad range of analytes, such as gases, heavy metal ions, glucose, amino acids, and compounds linked to disease [45]. As shown in Figure 4, biosensors are typically made up of three major parts. A physicochemical detector or transducer, a biological sensing element, and a signal processing system are a few of these. Signals are produced by interactions between biological sensing components and the target analyte. Sensing elements often consist of substances including organelles, microbes, tissues, antigens, enzymes, and nucleic acids, as well as cell receptors. After the sensor component and the target analyte contact, the signal is converted by the transducer into an electrical signal that can be measured and quantified. For this reason, the electrical signal is amplified by a signal-processing system and sent to a data processor, which converts it into a signal that can bemeasured in the form of a printout, digital display, or color shift [46].                    

5.1 Types of Nanobiosensors used in drug analysis

Fig.7 Demonstrates the various types of Nanobiosensor.

Although there are many other kinds of nanobiosensors, the following are the ones that are primarily employed in drug analyses:

5.1.1 Electrochemical Nano biosensors

The same parts needed for electrochemical sensors are also needed for electrochemical (bio) sensors, although with a few minor adjustments. Here, the bio receptor (such as nucleic acids, aptamers, antibodies, proteins, enzymes, or peptides) is linked to the transducer, which is the electrode surface that attracts the target and translates the binding events between the target and bio receptor into a measurable electrical signal proportionate to the concentration of the target. Analytical detection using electrochemical-based (bio) sensors depends on measuring the electrical current produced by a chemical reaction (such as a redox reaction) that takes place on the surface of a working electrode. This current is the outcome of electrolysis, which is brought on by the analyte's electrochemical oxidation or reduction. Higher selectivity and sensitivity in identifying analytes are among the advantages of the electrochemical approach over traditional analytical methodologies. There are further benefits associated with this method as well, such as lower limits of detection (LOD), acceptable stability, improved accuracy, affordability, faster analytical times, and larger linear responses. Pharmacological chemicals such as antidepressants, antibiotics, anti-inflammatory medicines can now be detected and analyzed using electrochemical-based (bio) sensors [47].

Systems for electrochemical detection and biosensing have the best ability to detect several analytes with a high degree of selectivity and sensitivity in complicated samples (like plasma and other clinical specimens). Bio/electrochemical activities take place at the interface of the electrochemical transducer surfaces (working electrode surface) in this sensing platform. Because the resulting electrochemical signals might be recorded, it was also possible to screen for and assess the specific binding affinity and catalytic efficiency between an analyte and a particular or immobilized bio-receptor. In many different fields, including microbiological detection, diagnosis of cancer, toxicity analysis, food quality control reliability, medical care, and health prognosis, electrochemical biosensors are used extensively [48].

5.1.2 Optical Nano biosensor

Analytical instruments with an integrated biorecognition component within an optical transducers system are called optical biosensors. An optical biosensor's basic function is to enable label-free, real-time parallel detection while producing signals that are proportionate to the analyte's concentration. Optical biosensors employ complete cells, tissues, aptamers, enzymes, and antibodies as biorecognition components. In optical biosensors, in response to chemical or physical modifications produced by the biorecognition elements, the transduction process causes a modification in the absorption, transmission, refraction, reflection, phase, amplitude, frequency, and/or light polarization. Optical biosensors are classified as label-free & label-based based on the premise. The interaction between the analyte and the transducer generates the observed signal in label-free sensing. In contrast, luminescence, fluorescence, or calorimetric techniques are used in label-based sensing to produce the optical signal. Optical concepts such as surface-enhanced Raman scattering (SPR), chemiluminescence, optical waveguide interferometry, evanescent wave (EW) fluorescence, and refractive index can all be used to create optical biosensors [49].

5.1.3 Piezoelectric Nanobiosensors

A class of analytical tools known as piezoelectric biosensors operates on the basis of recording affinity interactions. A sensor element that operates on the basis of oscillations changing as a result of a mass bound on the surface of a piezoelectric crystal is known as a piezoelectric platforms or piezoelectric crystal. This article examines biosensors that have been changed on the surface using an antigen or antibody, a molecularly engraved polymer, or genetic information. In terms of their operational principle, piezoelectric biosensors that incorporate molecularly imprinting polymers are quite similar to piezoelectric immunosensors. They interact directly with an analyte through an affinity process, which lowers the oscillation frequency that is being measured. Label-free analyte determination is a great use for piezoelectric biosensors [50].

5.1.4 Plasmon Surface Nanobiosensor

When a target analyte combines with the sensor's biorecognition segment, surface plasmon reverberation (SPR) biosensors use surface plasmon waves, or electromagnetic waves, to identify changes. Fundamentally, shifts in the refractive record, which is used to quantify or view the reaction occur when the SPR biosensor is exposed to motion. In order to see and be ready to interact with a particular analyte, the SPR transducer system is combining with the biomolecule/biorecognition section. As such, the refractive index at the sensor surface is altered when the target analyte interacts with the mounted biomolecule there.

The variations in the spreading, unwavering surface plasmon wave are conveyed by these motions, and this variation is measured to facilitate analysis. To verify the ongoing scope of test, a spectrophotometer is employed. Numerous biorecognition components, such as proteins, counteracting agents, antibodies, nucleic acids, and compounds, have been fused with SPR biosensors [51].

5.1.5 Enzyme based Nanobiosensors

Among the most popular and economically successful biosensors are those based on enzymes. As biosensor modifying agents, NMs increase the sensitivity of biosensors while significantly reducing their ability to detect, persist, respond, and have certain other analytical features. In enzyme-based biosensors, NMs are crucial because they increase the sensitivity and efficiency of the sensor. The distinct properties of these innovative nanoscale materials can significantly boost biosensors' sensing capabilities. Enzyme-based biosensors may benefit from the addition of NMs because they can significantly increase the surface area-to-volume ratio, which immobilizes more enzyme molecules and enhances the total enzyme substrate interaction. An enzyme is integrated as a bioreceptor or firmly connected to a physical transducer in enzymatic biosensors, which produce a discrete or continuously digital electronic/optical signal proportionate to the concentration of analyte in the sample. The detection of a co-substrate, or more accurately, the outcomes of the catalyzed reaction, is the foundation of enzyme-based analytical techniques. The first particular molecules to be employed as biosensors were enzymes. Enzyme-based electrochemical biosensors are some of the most sophisticated and profitable bioanalytical instruments available. This is due to the fact that enzymes are sold commercially. Due to its abundance of amine groups that can be used to immobilize biomolecules, polyamidoamine dendrimers have been used extensively in the development of biosensors and in the targeting of cancer cells [52].

5.1.6 DNA based Nanobiosensors

DNA-based biosensors are becoming a popular option for applying as nanowires and for detecting particular nucleic acid sequences, organic compounds, and heavy metal ions. A self-assembled monolayer or SAM for made up of a collection of single-stranded or double-stranded DNA molecules deposited on a metal surface is what makes up this kind of biosensor [53]. These biosensors include benefits including little sample preparation, quick response, affordability, and convenience of use. In addition to carrying genetic information, the nucleic acids like RNA and DNA have a high degree of selectivity and affinity for their target molecules [54].

5.2 Applications of Nanobiosensors

 In a traditional "off-site" analysis, the samples must be submitted to a lab for examination. These approaches are costly, time-consuming, and need the usage of highly skilled workers, yet they offer the best quantification accuracy and the smallest detection limits. Owing to the above-mentioned disadvantages, biosensor technology has attracted a lot of interest. The subject of developing biosensors has grown astronomically in recent years, and new applications in a variety of fields have emerged. Figure 6 below illustrates a few of these, which also include food safety, illness detection, defense, medicine development, and environmental monitoring. The list below includes a synopsis of a few carefully chosen examples and representations of biosensor applications in development [46].

The several kinds of biosensors, optical, electrochemical, and piezoelectric biosensors, have been discussed in this review to emphasize their vital uses in a wide range of industries. A few of the common industries using biosensors are the food industry to monitor quality and safety and help distinguish natural from artificial products; fermentation industry and saccharification process to identify exact glucose concentrations; and metabolic engineering to allow in vivo analysis of cellular metabolism. Important characteristics of biosensors and their importance in medical science include the early detection of human interleukin-10, which causes heart problems, and the quick detection of the human papillomavirus. Fluorescent biosensors are essential for both cancer research and medication discovery. In the field of plant biology, biosensor applications are widely used to identify the missing pieces needed for metabolic processes. There are other uses in the fields of clinical care, defense, and maritime applications [55]. The progress in nanobiosensor technology is opening doors for applications such as lab-on-a-chip (LOC) with a variety of nanobiosensors for quick screening of many analytes, biochips, point-of-care (POC) devices, and drug delivery platforms [56].

Fig.8 Illustration of a few applications of Nanobiosensors.

Our everyday lives are becoming more and more reliant on nanosensors to identify and quantify biomarkers. With the use of nanostructured materials, it is now possible to assess ultra-low concentrations  of target analytes, leading to a better understanding of intricate biological processes [57].  Nanosensors used for the precise detection and identification of illegal drugs, improved automation, cost-effectiveness, sensitivity, and selectivity of the manufactured sensors have all been demonstrated. In order to determine the interaction between the analyte and the bio recognition element that produced the best signal, these sensors are made to use biologically generated receptors with a transducer component [19].  

Analyte detection limits are increased by high-sensitivity nanosensors that make use of electrical, optics, and acoustic characteristics. Large surface area to volume ratios, compositions, charges, reactive sites, physical structures, and potential are only a few of the remarkable and unique qualities of nanomaterials that are useful for sensing. Prepping of samples, signal amplification, and the use of various transduction techniques all contribute to high sensitivity in analyte detection. When used in biomedical applications, such as early disease, toxin, or biological threat detection, the sensitivity and selectivity of such nanosensors can provide a number of benefits and lead to notable advancements in clinical, environmental, and industrial parameters. In many domains, including supramolecular chemical science, targeted drug delivery, early disease related biomarker identification, and the synthesis and evaluation of nanomaterials, the burgeoning field of nanotechnologies at the intersection of chemistry and life sciences presents a bright future [58].

Alpha-Hydrazinonitroalkene, a innovative drug, was analyzed in a human blood serum using a nanosensor based on a MWCNT-Sodium Dodecyl Sulphate Modified Electrode [59]. Pharmaceutical analysis applications, such as those using genuine samples like tablets or human serum, greatly benefit from the use of carbon-based nanosensors. Multiwalled carbon nanotubes on a glassy carbon electrode were used to accomplish an electroanalytical measurement of anxiolytic Buspirone hydrochloride [60]. Targeting single-base DNA errors is the primary application for plasmonic biosensors; nevertheless, single-cell biosensing offers potential benefits as well because it integrates fluorescence with far-field optical imaging. Ensuring high sensitivity and specificity is crucial when developing nanosensors for biomolecular evaluation of clinical samples. plasmonic sensors should be highly precise when measuring biomolecular targets at the single-molecule level [61].

6.1 Application of Nanosensors in Cancer Therapy Drug Detection 

One of the main risks to human health is cancer because of its complex structure and components that set it apart from healthy tissues. Traditional cancer treatment approaches include radiation (RT), chemotherapy, surgery, and combination therapy [62]. Around 10 million deaths globally will be attributed to cancer in 2020, according to WHO estimates and other important data. An earlier diagnosis increases the likelihood that the cancer will react to treatment, improving both the prognosis and the treatment cost. Cancer patients can have far better lives if their disease is detected early and treatment delays are avoided. Long-term patient survival may be increased and cancer diagnosis rates significantly lowered if nanomaterial-based sensors are developed that can detect and isolate cancer-specific indicators, migrating cancer cells, especially extracellular vesicles that are released by the tissue [7].Accurate early diagnosis of diseases has a significant impact on the future prospects and standard of life of cancer patients [63]. Monitoring effectiveness of drugs, evaluating treatment response, and directing individualized treatment plans all depend on the use of the nanosensors for cancer therapy drug detection. Nanosensors provide excellent sensitivity, specificity, and the capacity to identify medication concentrations in tumor tissues or circulating biomarkers.

Fig.9 Illustrates the impacts of Nanosensor technology on Healthcare outcomes.

Here is how cancer therapy drug detection can use nanosensors:

6.1.1 Monitoring of Specific Drug Delivery:

The field of nanomedicine has shown tremendous interest in tumor microenvironment sensitive drug delivery systems, which are "smart" formulations that demonstrate an immediately drug release profiles upon stimulation from tumor cellular surroundings. Cancer stimuli-responsive delivery of drugs could be accomplished via size contraction or expansion, surface charge modification, or control of other physiochemical characteristics. There are several difficulties with traditional aiming techniques, such as passive and active targeting [64]. There are great hopes for the application of nanotechnology in cancer treatment to deliver drugs. Furthermore, the promise of using nanomaterials in sensors to collect and recognize tumor-specific biomarkers, circulatory tumor cells, or extracellular vessels secreted by the tumor is that cancer can be detected much earlier, improving patient long-term survival. Furthermore, the patient's quality of life and therapeutic result will be enhanced by the individualized drug dosing made possible by the tracking of the concentration of anticancer drugs, which have a limited therapeutic window [65]. By utilizing at least two stage channels (drug/nanomaterial), nanosystems based on improved pharmacokinetics (PK), bioavailability, and biodistribution have been able to be constructed thanks to the use of nanotechnology to pharmaceutical research. Due to these benefits, the nanomaterials passively build up in the tumor (because of the increased permeability and retention, or EPR) effect, which lessens the negative effects of free medication [66].

6.1.2 Drug Detection within Cells:

Drug delivery methods based on nanoparticles (NPs) have demonstrated numerous benefits in the treatment of cancer, including improved pharmacokinetics, accurate target of tumor cells, decreased side effects, and decreased susceptibility to drug resistance. NPs utilized in medication delivery systems are typically selected or created based on the size and properties of the tumors in accordance with their pathophysiology. Through the transport effect of nanoparticles and the orientation effect of the targeted material after absorption, nano-carriers in chemotherapy mechanically target to malignant cells. The medications are then released onto the tumor cells to cause their death. Traditional chemotherapy drugs and nucleic acids are among the drugs found inside the nano-carriers, suggesting that they may be used in both gene therapy and cytotoxic treatments. Furthermore, NPs provide a platform that makes it possible to encapsulate and distribute some poorly soluble medications. Nano-carriers can lengthen the half-lives of medications and cause their accumulation in tumor tissues because of their size, surface properties, and ability to improve permeability and retention [67].

6.1.3 Monitoring of Drug Resistance:

The global development of resistance mechanisms is one of the biggest obstacles to developing an effective cancer treatment. The activation of resistance mechanisms in parallel pathways of signaling upon the shutdown of primary oncogenic routes allows cancer to reroute and proliferate. In addition to allowing for medication resistance, heterogeneity can be seen among genetic mutations, epigenetic patterns, tumor cells within patients, and between patient tumors. All of these factors can restrict the effectiveness of therapies. Nanotechnology may hold the key to improving the targeting of currently available treatments, boosting the effectiveness of locally applied drugs, reducing systemic toxicity, boosting imaging, boosting diagnostic sensitivity, and optimizing radiation therapy Through the use of dual-drug loading, triggered release, physical modalities, and multiple target components to eliminate malignant cells, nanoformulations can effectively counteract resistance mechanisms. Because tumors have poor lymphatic drainage and leaky blood arteries, nanoscale carriers can passively aggregate within them after passing through the tumor endothelium. Additionally, thanks to the special physico-chemical characteristics of nanomaterials, early cancer identification and improved patient outcomes are made possible by their use in extremely sensitive diagnostic procedure  [68].

6.1.4 Identification of Biomarkers to Assess Response to Treatment:

A common technique to obtain access to tumor tissue is a biopsy, which is an invasive and uncomfortable process for the patient. Biopsy is the process of taking samples from primary blood or other bodily fluids and analyzing biomarkers such circulating tumor cells (CTCs), Exosome (exosomes are plentiful in biofluids, carry RNA and proteins representative of the original cells, and remain stable for weeks, they have recently gained significant attention as highly potential cancer biomarkers [69].) and floating free DNA (cfDNA). It is a cutting-edge tool for the early diagnosis of NSCLC because of its features, which include continuous monitoring, convenience, non-invasiveness, and application for early prognosis. Tracking migrating tumour DNA (ctDNA), CTCs, and EVs in fluid secretions increases the likelihood of identifying potential recurrences and treatment responses in patients with lung cancer [70]. A promising cancer biomarker, circulating tumor DNA (ctDNA) in the blood plasma has been shown to be useful for non-invasive cancer identification, tailored treatment of advanced cancer, and cancer residual monitoring both during and after treatment [71].

Fig.10 Nanosensors for cancer therapy.

6.1.5 Nanoparticles Theranostic:

Considerable attention has been paid in the past 10 years to the usage of nanotheranostics as a novel means of diagnosis and treatment for a variety of illnesses, particularly cancer. Many strategies have been used to date to create smart nanotheranostics, which integrate diagnostic capabilities with bioactive targeting on particular tissues. Through simultaneous real-time monitoring of the therapy response, nanotheranostics can provide therapeutic substances. As so, the likelihood of administering too much or too little medication is reduced. To objectively track the medication delivery processes, a range of non-invasive imaging approaches have been applied Targeted delivery, controlled release, enhanced endocytosis transport efficiency, stimuli-responsive systems, and a combination of therapeutic modalities, including multimodality diagnosis and therapy, are just a few of the many capabilities of theranostic nanomedicine [72].

6.1.6 Non-Invasive Imaging Techniques:

By providing the best possible care for each patient individually, personalized medicine (PM) seeks to transform cancer therapy. By assisting in treatment selection, objective response monitoring, and follow-up therapy planning, nanothermonostics a hybrid treatment and diagnostic imaging integrated into a nanosystem are designed to realize PM's potential. While traditional imaging methods like CT, PET, MRI, and SPE (single-photon emission computed tomography) are commonly utilized in the theranostics field, optical imaging (OI) has certain benefits of its own, including reduced invasiveness, high sensitivity, and spatial and temporal resolution. In order to facilitate the creation of individualized treatments, it also permits multiplexing using DNA barcoding and multi-color imaging. It is turning out that the ability to combine treatment and diagnostics into one unit is revolutionizing modern medicine. Saved time and money aside, it also helps to mitigate some of the negative effects associated with traditional systemic methods [73].

6.1.7 In Vivo Monitoring Using Implantable Sensors:

By enabling individualized medication, in vivo biosensing holds the potential to completely transform the medical field. Imagine if clinically important health information could be continuously transmitted to a patient by simply implanting a sensor into them. Constant monitoring could provide a clear understanding of a person's baseline health, making little deviations from normalcy significant markers of an approaching illness. Another option is continuous therapeutic drug monitoring, which provides a personalized report on a drug's pharmacokinetics, potentially eliminating the need for guesswork in dosage. While there are many examples of sensors that are capable of identifying physiologically relevant analytes and have enormous potential for in vivo evaluation, there aren't many examples of biosensors that have been proven in pre-clinical animal research or that have been given the go-ahead to be implanted in people [74]. The ability to target cancer cells with extreme precision, minimize damage to healthy cells, and increase the effectiveness of therapeutic payloads are crucial benefits [75].

Researchers and physicians can develop more effective and individualized treatment plans for cancer patients by utilizing the potential of nanosensors to provide important insights into the workings of cancer therapy delivery of drugs and response.

Fig.11Types of Nanosensors used in cancer therapy drug detection.

Relying on the goals of laws and programs rather than their outcomes is a common mistake, as noted by Milton Friedman. Aiming to reduce poverty, promote socioeconomic inclusion, and safeguard the environment, Agenda 2030 has seventeen Sustainable Development Goals, or SDGs. An international list of tasks for sustainable growth, it has drawn criticism for being overly expansive, universal, ambitious, and possibly inconsistent, especially when it comes to the aims of environmental sustainability and socioeconomic development [76]. Every modern global agenda has included sustainable development; in an effort to create a more sustainable future, numerous objectives have been created. Introduced by the UN in 2015, the seventeen Sustainable Development Goals, or SDGs, are designed to address global economic, social, and environmental problems while advancing the idea of sustainability. In order to meet existing needs without jeopardizing future generations' ability to meet their own, development must be sustainable. Current definitions of sustainability are based on this definition, which was developed in the United Nations 1987 publication "Our Common Future," also referred to as the Report of Brundtland. There are 169 objectives throughout the 17 SDGs [77]. Robust biosensors contribute significantly to the SDGs [78]. The UNSDG objectives are met by using nanosensor technology for drug detection. The following SDG targets can be greatly attained thanks to the present advancements in nanosensor technology for drug analysis, as this review demonstrates.

Through Nanosensor technology, we are able to achieve these SDGs.

• Sustainable Development Goal SDG 3: Good health and well being
• Sustainable Development Goal SDG 12:Responsible consumption and production

Sustainable Development Goal SDG 3: Good health and well being

Ensure good health and encourage well-being among everyone at all ages, is the commitment made by the third Sustainable Development Goal (SDG3). Numerous factors, some intrinsic to each person but some influenced by the environment and financial situation, might affect health [79]. Undoubtedly, the utilization of nanotechnologies has facilitated advancements in the biotechnological, pharmaceutical, and medical fields, hence improving patients' quality of life and Health problems. Additionally,they have made medical processes easier, including follow-up monitoring, therapeutic interventions, and diagnosis. Developing new nanomaterials is a continuous effort to enhance disease detection and treatment in a focused, precise, effective, and long-lasting way, ultimately leading to more individualized, affordable, and secure medical procedures.Utilizing the appropriate nanomaterials and minimizing any potential negative effects are key to the potential of nanotechnology [80].

Target 3.3 (End Epidemics of Communicable Diseases); since the beginning of time, the human species has repeatedly experienced pandemics and epidemics of infectious diseases. The existence of fungi, bacteria, viruses, and parasites in unrefined wastewater can cause illnesses of the lungs, intestines, and other organs [81].Every illness has revealed new medical issues and the urgent need for interdisciplinary medical treatment to evolve quickly. Many illnesses, such as cancer, cirrhosis, and bacterial and viral infections, have been identified and diagnosed using nanoscale fast diagnostics and biosensors. By detecting molecular alterations prior to illness onset, these devices and detectors provide prompt prognostication and improved status monitoring. For the purpose of improving drug and particular medication delivery strategy efficiency, effective systems for drug delivery and nano-therapeutics have additionally generated a lot of interest. Since nanoparticles are small and have a large surface area, they can be delivered over an extended period of time without becoming harmful. The multidisciplinary use of nanosensors can link to several strategies for swiftly and successfully combating COVID-19 [82].

 Target 3.4 (Reduce Premature Mortality from Non-Communicable Diseases); the emergence of nanotechnology-based sensors has made it possible to detect and quantify a wide range of analytes with exceptional sensitivity and selectivity. This makes them perfect for uses in areas like food safety, illness diagnosis, and vital sign monitoring. These gadgets have made it possible to accurately and instantly detect and measure biological substances like proteins and nucleic acids. Additionally, they have made it possible for the creation of point-of-care tools that can quickly identify illnesses and track the effectiveness of treatment. Additionally the important application of nanosensors is the study of antibiotic resistance and medication discovery. High-throughput screening of potential drugs and the biological activity characterization of those candidates have been made possible by these technologies [83]. Nanosensors are also used to treat cancer. By targeting cancer cells more precisely and overcoming multidrug resistance in cancer tissue, nanoparticles can be used as an effective therapy. Because of its biocompatibility and extended drug release, polylactic acid (PLGA) is a commonly used polymer to create nanoparticles. It has also been used to create nanoparticles containing drugs for cancer therapy. Anticancer medications like paclitaxel, dexamethasone, 5-fluorouracil, and doxorubicin have all been effectively produced using PLGA [84].

Target 3.8: (Achieve Universal Health Coverage); Managing and treating a disease requires an understanding of its underlying causes. This includes learning about the patient's medical background, doing a physical examination, and applying diagnostic methods to identify and characterize symptoms. Diagnostic instruments should ideally be sturdy, sensitive, accurate, specialized, affordable, and easy to use. It is becoming more and more important to create nanotechnology-based diagnostic techniques that are quick, active, easy to use, and economical for identifying clinical samples because many diseases have the potential to cause epidemics and high rates of morbidity and mortality [85]. lately Technological developments in nanosensors may result in more easily available, cost-effective, and efficient diagnostic instruments, enhancing healthcare coverage and accessibility.

Target 3.9: (Decrease Illness and Death from Pollution and Hazardous Chemicals); Contaminants in pharmaceutical waste are growing daily along with the rate at which medications are produced. The main source of pharmaceutical contamination in water bodies is the discharge of pharmaceutical medicines and their metabolites. A form of biological waste known as pharmaceutical contaminants includes abandoned medications, unopened creams, hospital-acquired drugs containing animal waste, and other drugs. Graphene nanosheets, metal chalcogenides, boron nitride, graphite carbon nitride (g-C3N4), metal oxide nanorods, nanoflowers, and nano-leaves are examples of nanocomposites that have been effectively employed for the removal of pharmaceutical contaminants [86].

Sustainable Development Goal SDG 12: Responsible consumption and production

In essence, SDG 12 decouples financial development from unsustainable reserve usage and emissions and recovers waste and hazardous material management. It promotes for sustainable consumption and production. It specifically enquires for the ten-year plan of Programs on the Sustainable Consumption and Production, or SCP, to be put into effect, as well as for businesses to adopt more sustainable practises, reduce food and other waste, manage chemicals responsibly, utilise natural resources more efficiently, and procure goods in a sustainable manner [87]. The conclusion of the SDG 12 negotiations is a reflection of the 1990s production- and design-centered mindset, which is characterized by a favorable to businesses regulatory approach and a belief in the use of new technologies to solve problems [88]. This contradiction can hardly be addressed by SDG 12's voluntarism-focused agenda and its exclusion of important human rights measures. Instead, it perpetuates the systemic issues that have caused significant harm to society and the environment [89]. Advancement in drug analysis through nano scale sensors plays a major role in reaching SDG 12.It encourages more effective and sustainable development in health care and pharmaceutical practices.

Target 12.2 (Efficient Use of Natural Resources and Sustainable Management); With their widely recognized benefits of sensitivity, selectivity, affordability, ease of use, and the potential to be automated and miniaturized, nanodevices can be very useful as efficient tools in this sector [90]. Drug manufacture and testing waste less resources thanks to the accurate and effective drug analysis made possible by nanosensors.

Nanosensors provide precise dosing and administration, which helps cut down on waste and needless resource use.

Target 12.5: Decrease Waste Production Significantly: Because of the world population's rapid growth, there is a constant demand for food and medications. To address this issue, every nation is concentrating on boosting manufacturing and raising output levels. Human health is being impacted by the pollution of the food supply, soil, water, and air. Although the pharmaceutical business helps treat illnesses and save lives, it eventually contaminates the environment. Pharmaceutical waste pollutants are growing daily along with the rate at which medications are being produced. The main source of pharmaceutical pollution is the discharge of prescription medications and their byproducts into aquatic environments. The identification and elimination of pharmaceutical contaminations have made considerable use of nano-sensors [86]. Because they are versatile and may be inexpensive, devices like nanosensors have become popular as a substitute to traditional analysis techniques for tracking and finding traces of pollutants in these settings [91].Additionally, the focus of nanosensor technology is on at-home and real-time point-of-care applications for healthcare [92].

Future prospects

The primary goal of nanotechnology was to take use of the benefits of material shrinkage and investigate the possibility of making fascinating technologies that are much smaller in the future [93].Nano technologies are now crucial to the advancement of tools like chips, sensors, and probes in drug analysis. In this area of contemporary analytical chemistry, which is defined by the legal framework influencing work implementation and results as well as the range of analytes that can be studied, this review article unequivocally demonstrates that nano-enabled sensors may serve as quick, dependable, and reasonably priced analytical tools used for drug analysis. A wide range of intriguing nanosensor designs have been developed, as evidenced by the analysis of the chosen samples. Even then, relatively few nanodevices are routinely used in forensic practice; this is likely due to the fact that many claimed innovations were not applied to materials with the crucially complicated grade of complexity. To ensure that nanodevices are better prepared for these samples and meet the requirements for true applicability in this field, significant research efforts will need to be undertaken in the near future. By constructing the gadget with nanomaterials, the sense and efficiency of the apparatus are being enhanced. Devices with numerous novel signal transduction technologies have been made possible by the application of nanomaterials. The production costs of nanodevices can be lowered, sensitivity levels can be increased, and devices can be miniaturized to tiny sizes. Because these devices are compact, lightweight, and simple to use in daily tasks, functioning will be significantly improved [90].

More creativity is required, along with fast throughput and improved measurement resolution. However, its applications in biomedicine, ranging from illness therapy to drug detection, are incredibly promising. Real-time monitoring of various elements can be facilitated by tiny metabolite detection or single-cell analysis. The ability to create novel nanoprobes for the sensitive detection of biomolecules, such as enzymes or biomarkers, is made possible by the nanoscale size of receptors, pores, or other functional components of cells. Future hope for the detection and avoidance of potential risks for life-threatening illnesses or improved infectious disease surveillance is demonstrated by the development of small, biocompatible devices that can detect quickly and non-invasively. The incorporation of other medications, such as fluorophore on nanoparticles that may be utilized for both imaging and therapy, is another area of exploration. Biomolecules including DNA, proteins, ions, and tiny molecules can be detected with high sensitivity, which has applications in drug screening, early illness diagnosis, and the creation of biomarkers. Given their reduced adverse effects, targeted medicine delivery mediated by nanoparticles has enormous potential. One recent development in nanotechnology that will increase our understanding of developing infections [93]. Nanosensor-based drug analysis has a bright future ahead of it, with numerous significant fields of growth and possible impacts on sensitivity, selectivity, cost, and detection limit. Lower detection limits and increased sensitivity are made possible by nanosensors.

Advancement in drug analysis through Nano scale sensors evaluates the noteworthy progress in nanosensor technology for the drug analysis and detection. As well-known, drugs play a major role in a number of healthcare domains, including avoiding illnesses, treatment, chronic condition management, and general quality of life enhancement. Thus, it's critical to evaluate drugs to prevent any negative effects. To guarantee the security, effectiveness, and caliber of pharmaceuticals, drug analysis is essential. It is vital to the protection of public health since it helps to discover possible hazards and side effects related to medications, making sure that patients receive only safe products. A number of conventional techniques are employed in drug analysis. However, there are numerous drawbacks of these delayed approaches. This review emphasizes the several benefits provided by nanosensor technology, including the ability to detect drugs early and accurately, to create customized treatment plans, and to monitor drug efficacy in real time. Additionally, it highlights the key categories of nanosensors used in drug analysis.The study also looks at how, through encouraging innovation, supporting sustainable practices, and advancing healthcare accessibility, nanosensors help to achieve a number of Sustainable Development Goals (SDGs), including SDG 3 (Good Health and Well-Being) and SDG 12 (Responsible Consumption and Production). It presents a bright future for drug analysis using nanosensors, imagining improvements like increased sensitivity, connection with modern health technologies, and customized treatment approaches. These future directions highlight the critical role that nanosensor technology will play in influencing the direction of medicine and have the potential to significantly transform the way that healthcare is delivered and improved outcomes.

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