**3.2 Nanosensors**

imaging. UV-vis and photoluminescence spectroscopy are generally used for characterization of quantum dots. Thanks to these methods, it is possible to perform fast, undamaged and contactless characterization. The use of photomodulated reflectance spectroscopy, an experimental method, offers a wide range of critical point advantages. The optical properties of quantum dots can be controlled by the dimensions of the dots. The size of the quantum dots can be characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Optical activity properties and particle sizes of quantum dots can be measured by photoluminescence excitation and Raman scattering spectroscopy. Atomic force microscopy (AFM), scanning tunneling microscopy (STM) and transmission electron microscopy (TEM) analysis methods are used to display the particle sizes. However, the best analysis results are obtained

*Smart Nanosystems for Biomedicine, Optoelectronics and Catalysis*

**3. Nanodevices and the complex nanostructures used in nanodevices**

gene therapy, machine design, military, and space science (**Figure 8**).

In order to develop nanorobots, firstly, the nanoparticles must be accurately and adequately analyzed, and the atomic arrays must be designed correctly. The essential components of nanorobots are nanocomputer. Especially in the field of health, it is vital for the rapid and accurate diagnosis and monitoring of diseases. In recent years, the need for diagnosis and treatment of cancer diseases, which is rapidly becoming widespread day by day, has significantly increased. Besides, there is an increasing need for nanorobots in environmental engineering, food technologies,

As a product of the physical and biological sciences, biochips provide molecular analysis with high efficiency. Especially in gene engineering, biology, and medicine, biochips that do wonders in early diagnosis of diseases also enable gene sequencing, pharmacology and toxicology, analysis of DNA/RNA strands, and accurate identification of proteins. The most current studies are the determination of gene expression between human cells and tissue. In this way, global gene expression analysis is highly illuminating in the early detection of tumors in the living body. Application areas of biochips can be listed as a diagnostic tool in clinical medicine, quantifying

with AFM and TEM analysis methods.

**3.1 Nanorobotics**

*3.1.1 Biochips*

**Figure 8.** *The nanorobotics.*

**120**

Nanosensors are a combination of chemical, biological, and surgical sciences used to deliver nanoparticles to the world macroscopically. Nanosystems such as porous silicon, nanoparticles, nanoprobes, nanowires, nanotubes are widely used in the design of nanosensors. Examples of nanoparticles used in the design of nanosystems are MNPs magnetic nanoparticles, AuNPs gold nanoparticles, upconversion nanoparticles, QDs quantum dots, SWNTs single-wall carbon nanotubes, MWNTs multiwall carbon nanotubes, nano barcode technology and electronic nose [21]. These devices are tiny devices that can detect and respond to physical stimuli such as biological and chemical substances, displacement, motion, force, mass, acoustic, thermal and electromagnetic. In the literature studies, many nanosensors were synthesized for different purposes (**Table 2**).


#### **Table 2.**

*Some examples of nanosensors, according to the literature.*

**Figure 9** shows the different uses of areas of nanosensors. The features to be considered in the design of nanosensors are selectivity, calibration requirement, reproducibility, stability, high sensitivity, wide measuring range, service life, the limit of determination, and sterilization (**Figure 10**).

Nanosensors consist of transducers and nanoparticles. Nanosensors can be designed as amperometric, voltammetric, potentiometric, colorimetric, SPR, fluorescence, optical fiber, SERS, acoustic and pieozoelectric transducer. Metallic, magnetic, quantum dots, graphene oxide, carbon nanotubes and upconversion nanoparticles are commonly used in nanosensors.

Xiang et al. [22] designed black phosphorene nanosensors for voltammetric analysis of ochratoxins. As known, ochratoxins have been identified as immunotoxic, nephrotoxic and carcinogenic in humans by the International Agency for Research on Cancer (IARC). Therefore, rapid and precise measurements are needed to determine whether ochratoxins are above the limit values in food components. Black phosphenes (BP) are widely used in the design of nanosensors because of their precise measurement capabilities. However, black phosphenes are highly reactive to water and oxygen, so they are easily affected by ambient conditions, so they lose their stable structure. In order to prevent this problem, the stability of BPs with covalent aryl diazonium, ligand surface coordination and coating materials is increased. The interaction of Ag+ ions and BPs in the N-methyl pyrrolidone (NMP) environment increases the super electrochemical properties considerably.

Soleja et al. [23] devised fluorescence resonance energy transfer (FRET) based nanosensors to detect arsenic metal and to determine its concentration. As it is known, arsenic is a toxic and heavy metal that has a carcinogenic effect and can cause serious health problems. Therefore, it is necessary to determine the concentration values accumulated in the living organism easily. The transcriptional repressor Arsr of the ars has an affinity for As3+ and the arsenic ions are thus more

easily bound. This process makes it possible to develop fluorescence resonance energy transfer (FRET) based nanosensors. The donor and acceptor perform ArsR binding with arsenic at the N- and C-terminus to obtain a recombinant protein. Fluorescence sensors technology enables sensitive and non-destructive detection of signals in food additives and metal ions to detect environmental contamination. Fluorescence sensors have two important units: receptor and signal. As the target analyte concentrations are usually low, specific recognition for receptors is of great importance. Enzymes, aptamers and natural receptors, as well as artificial polymeric receptors or molecularly imprinted polymers, are used as receptors. Molecularly imprinted polymers are cross-linked polymers containing voids specific to analytes. These gaps support high selectivity. Comparing molecularly imprinted polymers and natural receptors, it is concluded that molecularly imprinted polymers show high chemical and physical stability, low cost and easy preparation properties. In fluorescence signal units, quantum dots, metal nanoclusters and

organic dyes are often preferred as fluorescence sensors components.

strengthened the measuring ability of the system.

ties for quantum dots in the presence of heavy metals.

mance, sensitivity and selectivity.

**123**

**Figure 10.**

*The important properties of nanosensors.*

*The Components of Functional Nanosystems and Nanostructures*

*DOI: http://dx.doi.org/10.5772/intechopen.92027*

Luo et al. [34] detected *E. coli* bacteria in milk by using radial flow chromatographic immunoassay (RFCI) method using gold nanoparticles as a chromatic agent. Hunter et al. [35] synthesized nanobiosensors to quickly detect pathogenic bacteria in serum with the optofluidic (surface-enhanced Raman scattering) SERS method. In this study, a hollow core photonic crystal fiber filled with microfluidics was used as the main converter. This system can be repeatedly renewed by washing with a liquid that can dissolve the analyte. The use of silver nanoparticles greatly

It can be said that the use of silver and gold nanoparticles in synthesized nanosensors gives very positive results in parameters such as measurement perfor-

Molecularly imprinted polymer receptor fluorescent sensors have several disadvantages, although they have many advantages in biology, environmental chemistry, food technology, food packaging, microbiology, pharmacology and medicine. For example, it is, unfortunately, possible to mention environmental harm proper-

**Figure 9.** *Different uses areas of nanosensors.*

*The Components of Functional Nanosystems and Nanostructures DOI: http://dx.doi.org/10.5772/intechopen.92027*

#### **Figure 10.**

**Figure 9** shows the different uses of areas of nanosensors. The features to be considered in the design of nanosensors are selectivity, calibration requirement, reproducibility, stability, high sensitivity, wide measuring range, service life,

Nanosensors consist of transducers and nanoparticles. Nanosensors can be designed as amperometric, voltammetric, potentiometric, colorimetric, SPR, fluorescence, optical fiber, SERS, acoustic and pieozoelectric transducer. Metallic, magnetic, quantum dots, graphene oxide, carbon nanotubes and upconversion

environment increases the super electrochemical properties considerably.

Soleja et al. [23] devised fluorescence resonance energy transfer (FRET) based nanosensors to detect arsenic metal and to determine its concentration. As it is known, arsenic is a toxic and heavy metal that has a carcinogenic effect and can cause serious health problems. Therefore, it is necessary to determine the concentration values accumulated in the living organism easily. The transcriptional repressor Arsr of the ars has an affinity for As3+ and the arsenic ions are thus more

Xiang et al. [22] designed black phosphorene nanosensors for voltammetric analysis of ochratoxins. As known, ochratoxins have been identified as immunotoxic, nephrotoxic and carcinogenic in humans by the International Agency for Research on Cancer (IARC). Therefore, rapid and precise measurements are needed to determine whether ochratoxins are above the limit values in food components. Black phosphenes (BP) are widely used in the design of nanosensors because of their precise measurement capabilities. However, black phosphenes are highly reactive to water and oxygen, so they are easily affected by ambient conditions, so they lose their stable structure. In order to prevent this problem, the stability of BPs with covalent aryl diazonium, ligand surface coordination and coating materials is increased. The interaction of Ag+ ions and BPs in the N-methyl pyrrolidone (NMP)

the limit of determination, and sterilization (**Figure 10**).

*Smart Nanosystems for Biomedicine, Optoelectronics and Catalysis*

nanoparticles are commonly used in nanosensors.

**Figure 9.**

**122**

*Different uses areas of nanosensors.*

*The important properties of nanosensors.*

easily bound. This process makes it possible to develop fluorescence resonance energy transfer (FRET) based nanosensors. The donor and acceptor perform ArsR binding with arsenic at the N- and C-terminus to obtain a recombinant protein.

Fluorescence sensors technology enables sensitive and non-destructive detection of signals in food additives and metal ions to detect environmental contamination. Fluorescence sensors have two important units: receptor and signal. As the target analyte concentrations are usually low, specific recognition for receptors is of great importance. Enzymes, aptamers and natural receptors, as well as artificial polymeric receptors or molecularly imprinted polymers, are used as receptors. Molecularly imprinted polymers are cross-linked polymers containing voids specific to analytes. These gaps support high selectivity. Comparing molecularly imprinted polymers and natural receptors, it is concluded that molecularly imprinted polymers show high chemical and physical stability, low cost and easy preparation properties. In fluorescence signal units, quantum dots, metal nanoclusters and organic dyes are often preferred as fluorescence sensors components.

Luo et al. [34] detected *E. coli* bacteria in milk by using radial flow chromatographic immunoassay (RFCI) method using gold nanoparticles as a chromatic agent. Hunter et al. [35] synthesized nanobiosensors to quickly detect pathogenic bacteria in serum with the optofluidic (surface-enhanced Raman scattering) SERS method. In this study, a hollow core photonic crystal fiber filled with microfluidics was used as the main converter. This system can be repeatedly renewed by washing with a liquid that can dissolve the analyte. The use of silver nanoparticles greatly strengthened the measuring ability of the system.

It can be said that the use of silver and gold nanoparticles in synthesized nanosensors gives very positive results in parameters such as measurement performance, sensitivity and selectivity.

Molecularly imprinted polymer receptor fluorescent sensors have several disadvantages, although they have many advantages in biology, environmental chemistry, food technology, food packaging, microbiology, pharmacology and medicine. For example, it is, unfortunately, possible to mention environmental harm properties for quantum dots in the presence of heavy metals.
