**3. Nucleic acids/graphene oxide-based biosensor**

Previous literature indicated that the GO-chitosan composite could also be used for DNA biosensor fabrication [24]. The GO-chitosan electrode was activated by glutaraldehyde and covalently cross-linked with *Salmonella typhi* specific 5′-amine labeled single-stranded (ss)

**Figure 15.** The scheme of ssDNA/GO-chitosan/ITO bioelectrode [24].

DNA probe (5'NH2 -ssDNA probe) (**Figure 15**). This DNA biosensor exhibited good ability to detect both complementary and non-complementary target. The linear range of detection was 10 fM–50 nM and the detection limit was 10 fM.

Zhang et al. [25] decorated gold nanorods (Au NRs) onto GO sheets and constructed a DNA biosensor (**Figure 16**). The AuNRs were prepared via a seed-mediated method and then composited with GO via electrostatic self-assembly. This biosensor exhibits significant selectivity and can distinguish complementary DNA in the presence of the 100-fold amount of single-

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http://dx.doi.org/10.5772/intechopen.78222

Min et al. [26] designed a nano graphene oxide (NGO) based miRNA biosensor on evaluating target miRNA expression levels in living cells (**Figure 17**). The dye-labeled peptide nucleic acid (PNA) probes were binding onto the surface of NGO. In this biosensor, NGO and PNA acted as fluorescence quencher and probe, respectively. The miRNA expression levels can be evaluated by detecting the fluorescence quenching of the dye-labeled on PNA. The results showed that the biosensor exhibited a low detection limit (1 pM) and can detect the dynamic change in expression levers of the specific miRNA in stem cell

Graphene oxide is one of many unique carbon materials, which displayed potential applications in the development of next-generation biosensors owing to its various physical and chemical properties. The functionalization of GO leads to the adsorption of various biomacromolecules, including enzymes such as glucose oxidase, horseradish peroxidase, laccase, and nucleic acids such as DNA and RNA for biosensing applications. The major prospect to be addressed in the future is the increasing demand for the engineering of biosensors

base mismatched DNA.

**Figure 17.** The scheme of PNA/NGO biosensor [26].

differentiation [26].

**4. Conclusion and outlook**

**Figure 16.** The scheme of DNA/AuNRs/GO biosensor [25].

**Figure 17.** The scheme of PNA/NGO biosensor [26].

DNA probe (5'NH2

10 fM–50 nM and the detection limit was 10 fM.

66 Graphene Oxide - Applications and Opportunities

**Figure 15.** The scheme of ssDNA/GO-chitosan/ITO bioelectrode [24].

**Figure 16.** The scheme of DNA/AuNRs/GO biosensor [25].


detect both complementary and non-complementary target. The linear range of detection was

Zhang et al. [25] decorated gold nanorods (Au NRs) onto GO sheets and constructed a DNA biosensor (**Figure 16**). The AuNRs were prepared via a seed-mediated method and then composited with GO via electrostatic self-assembly. This biosensor exhibits significant selectivity and can distinguish complementary DNA in the presence of the 100-fold amount of singlebase mismatched DNA.

Min et al. [26] designed a nano graphene oxide (NGO) based miRNA biosensor on evaluating target miRNA expression levels in living cells (**Figure 17**). The dye-labeled peptide nucleic acid (PNA) probes were binding onto the surface of NGO. In this biosensor, NGO and PNA acted as fluorescence quencher and probe, respectively. The miRNA expression levels can be evaluated by detecting the fluorescence quenching of the dye-labeled on PNA. The results showed that the biosensor exhibited a low detection limit (1 pM) and can detect the dynamic change in expression levers of the specific miRNA in stem cell differentiation [26].
