**3.3 Biosensors**

Biosensors are formed as a result of combining the receptor and transformer components. Receptors have a biomolecular structure. Physical signals are measured by combining selectively interacting analytes, biological sensors (enzymes, antibodies, immuno-agents, nucleic acids, microorganisms, cells, tissues), and physicochemical transducers (electrodes, transistors, thermistors, optical fibers, piezoelectric crystals). Electrical signals are obtained from these measured physical signals [36]. The working principles of biosensors are based on this basis. **Figure 11** schematizes biosensors. **Table 3** summarizes the literature studies.

There are some crucial advantages of using nanotechnology in the construction of biosensors. Nanoelectronic particles increase the memory and processing capabilities of biosensors and facilitate analysis. Besides, it facilitates the identification of microorganisms, provides high selectivity and long life. It also offers the possibility to work without damaging living cells [36]. **Table 3** shows the use of some biosensors according to the literature. **Figure 12** shows some examples of biosensor technology.

Liang et al. [37] synthesized biosensors for the detection of hydrogen peroxide using carbonization with graphene nanoplates derived from ficus fruits. As is known, hydrogen peroxide is an intermediate commonly used in biological test steps, clinical diagnoses, enzymatic and many other chemical reaction environments. Since it is used so often, it is of great importance to quantitatively analyze hydrogen peroxide. It is usually analyzed by colorimetric, photochemical and electrochemical techniques. The most advantageous technique among these techniques is the electrochemical technique. Because electrochemical techniques allow fast, cheap and real-time measurements. The carbon sources are commonly used as active substances in many kinds of research.

Ma et al. [39] synthesized gold probe-based strip biosensors to diagnose liver cancer tumors. Liver cancer is the most common type of cancer in the world and is highly affected by environmental and genetic factors. Early diagnosis is vital because in some cases the patient may lose his liver only a few months after being diagnosed. In this literature study, single nucleotide polymorphism (SNP) was used as a genetic marker for gene diagnosis of the disease. Thanks to the colloidal gold strip nanoparticles, the SNP diagnosis makes exceptionally accurate diagnoses in just a few minutes. Colloidal gold strips are of great interest in the environment, food safety and medicine as they offer a fast, precise, high selectivity and inexpen-

**Purpose of usage Biosensors References**

peroxide biosensor

Pt nanoclusters

Detection of lysozyme Aptamer-based electrochemical biosensors [41] Detection of arsenic and mercury Metallothionein-based biosensor [42] Detection of malachite green Free microcantilever based biosensor [43]

Detection of escherichia coli Label-free amperometric biosensor [46]

Naked-eye detection of aflatoxin b1 Label-free colorimetric biosensor [48]

Refractive index sensor A single-layer guided-mode resonant optical biosensor

Biosensor based on triplex DNA-templated Ag/

Gold probe with lateral flow strip biosensor [39]

An RGONS-based biosensor [40]

Surface plasmon resonance biosensor [45]

Autocrine motility factor-phosphoglucose isomerase' based on a biosensor

High-sensitivity nonenzymatic hydrogen

[38]

[37]

[44]

[47]

For the detection of single-nucleotide

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

*The Components of Functional Nanosystems and Nanostructures*

Green synthesis of porous graphene-

For simultaneous imaging of P53 and

methylquinoxaline-2-carboxylic acid

Electrochemical detection of the human

*Some examples of biosensors according to the literature.*

Detection of single nucleotide polymorphism of tumor

P21 mRNA in living cells

The determination of 3-

cancer biomarker

**Table 3.**

**Figure 12.**

*Some examples of biosensor technology.*

variant

like nanosheets

Fana et al. [40] also synthesized reduced graphene oxide-based biosensors to diagnose liver cancer. Graphene oxides are preferred as nanoparticles due to their electronic, mechanical and thermal stability. However, in-vitro assays should be

kept in limited amounts for use in living cells due to their toxic effects.

sive method.

**125**

**Figure 11.** *Schematic representation of biosensors.*

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


#### **Table 3.**

**3.3 Biosensors**

technology.

**Figure 11.**

**124**

*Schematic representation of biosensors.*

Biosensors are formed as a result of combining the receptor and transformer components. Receptors have a biomolecular structure. Physical signals are measured by combining selectively interacting analytes, biological sensors (enzymes, antibodies, immuno-agents, nucleic acids, microorganisms, cells, tissues), and physicochemical transducers (electrodes, transistors, thermistors, optical fibers, piezoelectric crystals). Electrical signals are obtained from these measured physical signals [36]. The working principles of biosensors are based on this basis. **Figure 11**

There are some crucial advantages of using nanotechnology in the construction of biosensors. Nanoelectronic particles increase the memory and processing capabilities of biosensors and facilitate analysis. Besides, it facilitates the identification of microorganisms, provides high selectivity and long life. It also offers the possibility to work without damaging living cells [36]. **Table 3** shows the use of some biosensors according to the literature. **Figure 12** shows some examples of biosensor

Liang et al. [37] synthesized biosensors for the detection of hydrogen peroxide

using carbonization with graphene nanoplates derived from ficus fruits. As is known, hydrogen peroxide is an intermediate commonly used in biological test steps, clinical diagnoses, enzymatic and many other chemical reaction environments. Since it is used so often, it is of great importance to quantitatively analyze hydrogen peroxide. It is usually analyzed by colorimetric, photochemical and electrochemical techniques. The most advantageous technique among these techniques is the electrochemical technique. Because electrochemical techniques allow fast, cheap and real-time measurements. The carbon sources are commonly used as

schematizes biosensors. **Table 3** summarizes the literature studies.

*Smart Nanosystems for Biomedicine, Optoelectronics and Catalysis*

active substances in many kinds of research.

*Some examples of biosensors according to the literature.*

#### **Figure 12.** *Some examples of biosensor technology.*

Ma et al. [39] synthesized gold probe-based strip biosensors to diagnose liver cancer tumors. Liver cancer is the most common type of cancer in the world and is highly affected by environmental and genetic factors. Early diagnosis is vital because in some cases the patient may lose his liver only a few months after being diagnosed. In this literature study, single nucleotide polymorphism (SNP) was used as a genetic marker for gene diagnosis of the disease. Thanks to the colloidal gold strip nanoparticles, the SNP diagnosis makes exceptionally accurate diagnoses in just a few minutes. Colloidal gold strips are of great interest in the environment, food safety and medicine as they offer a fast, precise, high selectivity and inexpensive method.

Fana et al. [40] also synthesized reduced graphene oxide-based biosensors to diagnose liver cancer. Graphene oxides are preferred as nanoparticles due to their electronic, mechanical and thermal stability. However, in-vitro assays should be kept in limited amounts for use in living cells due to their toxic effects.

Khan et al. [41] synthesized aptamer-based electrochemical biosensors for lysozyme determination. These biosensors are electronic and disposable biosensors. They used the inkjet-printing method for the detection of lysozyme which is a biomarker in the diagnosis of diseases. Carbon nanotubes and the single-stranded DNA were used for aptamer immobilization on the electrode. Thus, inks containing a mixture of carbon nanotube-aptamer complexes were synthesized. Generally, the main reasons for the use of aptamers in biosensor syntheses are resistance to environmental conditions, thermal and chemical stability, and increasing the binding efficiency. In addition to these advantages, it is possible to synthesize inexpensive biosensors, have a long shelf life and can be reproduced.

that nano-sized particles can be given unique and extraordinary abilities. This new technology is pushing dreams together and even promises to go beyond the borders of a futuristic imagination. Nanotechnology, which opens the door to extraordinary innovations in many engineering applications and medicine, brings many definitions such as nanoparticles, quantum dots, nanosensors, biosensors, nanospheres and nanorobots to our lives. The toxicities of quantum dots are very important for in-vivo experiments in agricultural applications. The best way to solve this problem is to secure it by bioconjugating it with coatings, proteins and peptides to protect and stabilize the surface of quantum dots. In addition, the choice of rounded quantum dots called colloidal in biosensing solutions can prevent possible problems. Using a non-toxic titanium dioxide compound can also solve the toxicity problem in

*The Components of Functional Nanosystems and Nanostructures*

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

Biological recognition systems connected to a transducer are effective in the specificity and selectivity of biosensors. Therefore, the most important part in a biosensor mechanism is bioreceptor synthesis. In the literature searches, biosensors for the detection of many diseases, viruses and bacteria were synthesized. However, in the applied methods, dual-aptamer biosensors generally give more precise and accurate measurements than single-aptamers. Multiple amplification reactions with fluorescence, colorimetric or electrochemical methods give better results. The more specific aptamers are used, the greater the measurement accuracy. The use of silver and gold nanoparticles in biosensor synthesis greatly increases the measuring ability of the system. Therefore, the repeatability properties of the probes will also be supported. In addition, metal organic framework compounds greatly increase the measuring ability due to their large surface areas, especially in the modification of electrodes for biosensor synthesis based on the measurement of electrochemical

Even though this new technology enables rapid, inexpensive, reliable, reproducible, high-precision measurement, diagnosis and analysis in many scientific fields, the studies to be carried out in this field in the coming years will provide meaningful grounds for solving existing problems or developing more advanced technologies. It should be noted that nanotechnological systems have a significant effect on polymers. Because polymers enable easy sterilization of synthesized nanoparticles. It also increases the loading capacity of the active substance and allows the synthesis of non-toxic particles, which can be degraded and decomposed in a physiological environment. Thanks to these advantages, it supports controlled release systems and bioavailability. It makes the world of the future a candidate for

in vitro applications.

signals.

**127**

the dream of the future.

Zhong et al. [49] synthesized fluorescence biosensor to detect *Pseudomonas aeruginosa* bacteria in food products. They performed the synthesis step using the copolymer points of dual-aptamer-labeled polydopamine-polyethyleneimine. According to the study of this article, it is seen that dual-aptamer biosensors enable more sensitive and accurate measurements than single-aptamer biosensors. Therefore, it has been concluded that the use of dual-aptamer-labeled polydopaminepolyethyleneimine copolymer points can be used in different alternative methods. Zhang et al. [50] synthesized colorimetric sensors for the detection of *Escherichia coli* and *Staphylococcus aureus* bacteria. It is based on the principle of separating and detecting bacteria from the medium using aptamer-based magnetic beads. Quantitative measurements of the growth kinetics of bacteria were measured by measuring the conductivity changes occurring in the environment depending on time. However, it was emphasized that the synthesized biosensor should be supported with different methods in sensitivity measurements. For this, methods such as changes in analyte volume and prolongation of incubation are recommended. Li et al. [51] used multiple amplification reactions and electrochemical methods to detect *E. coli* bacteria. First, the target sequences extracted from *E. coli* O157: H7 were converted to executive DNA and amplified. Next, a large number of transformed nucleic acid sequences were amplified by the RCA reaction. Then, DNA sequences were immobilized and electrochemical signals were measured with the help of electrochemical indicators. As a result, it is suggested that more effective results can be obtained in detecting pathogenic bacteria in living organism by developing multiple amplification methods.

Zhan et al. [52], synthesized aptasensors with the amplification method for the colorimetric detection of *Listeria monocytogenes*. In this study, enzyme dependent aptasensors were developed by rotary circle amplification (ELARCA) analysis. The study is based on the selectivity race between an aptamer specific for the bacteria of the *Listeria monocytogenes* and the biotin probe and the RCA probe. Adding bacteria to the environment prepares the medium suitable for the RCA probe, which starts the RCA process (rolling circle amplification), and causes the biotin probe to be exposed. In the presence of RCA buffer, multiple DNA copies are formed by binding to the biotin probe. In the presence of the enzyme substrate in the medium, (horse radish peroxidase), the chromophore group produced by HRP enables colorimetric measurement analysis.

As a result, it is thought that the determination of more specific aptamers for bacteria may be more developer for measurement accuracy and accuracy in the study that allows successful measurements.
