A quartz crystal microbalance DNA hybridization biosensor, based on thiol-derivatized peptide nucleic acid (PNA) probes, offers unusual in situ differentiation of single-base mismatches. A large excess of a single-base mismatch oligonucleotide has no effect on the frequency response of the target. Such remarkable distinction between perfect matches and mismatches is illustrated by the detection of a common mutation in the p53 gene. The greater specificity of the new mass-sensitive indicatorless hybridization device over those of analogous PNA-based carbon electrodes is attributed to the formation of a PNA monolayer and the use of a hydrophilic ethylene glycol linker. The improved specificity is coupled to very fast (3-5 min) hybridization in a low-ionic-strength medium.
An electrochemical biosensor protocol for the detection of radiation-induced DNA damage is described. The procedure employs a dsDNA-coated screen-printed electrode and relies on changes in the guanine-DNA oxidation signal upon exposure to ultraviolet radiation. The decreased signal is ascribed primarily to conformational changes in the DNA and to the photoconversion of the guanine-DNA moiety to a nonelectroactive monomeric base product. Factors influencing the response of these microfabricated DNA sensors, such as irradiation time, wavelength, and distance, are explored, and future prospects are discussed. Similar results are given for the use of bare strip electrodes in connection with irradiated DNA solutions.
Biosensors-based devices are transforming medical diagnosis of diseases and monitoring of patient signals. The development of smart and automated molecular diagnostic tools equipped with biomedical big data analysis, cloud computing and medical artificial intelligence can be an ideal approach for the detection and monitoring of diseases, precise therapy, and storage of data over the cloud for supportive decisions. This review focused on the use of machine learning approaches for the development of futuristic CRISPRbiosensors based on microchips and the use of Internet of Things for wireless transmission of signals over the cloud for support decision making. The present review also discussed the discovery of CRISPR, its usage as a gene editing tool, and the CRISPRbased biosensors with high sensitivity of Attomolar (10 −18 M), Femtomolar (10 −15 M) and Picomolar (10 −12 M) in comparison to conventional biosensors with sensitivity of nanomolar 10 −9 M and micromolar 10 −3 M. Additionally, the review also outlines limitations and open research issues in the current state of CRISPR-based biosensing applications.
Nucleic acid hybridization forms the basis for the diagnosis of genetic and infectious diseases. Electrochemical biosensors, coupling the inherent specificity of DNA recognition reactions with the high sensitivity of physical transducers, thus hold great promise for sequence‐specific detection. An electrochemical biosensor for the voltammetric detection of DNA sequences related to the hepatitis B virus (HBV) is described. Synthetic single‐stranded oligonucleotides (“probe”) have been immobilized onto carbon paste electrodes with the adsorption at a controlled potential. The probes were hybridized with different concentrations of complementary (‘target’) sequences. The formed hybrids on the electrode surface were evaluated by differential pulse voltammetry using cobalt phenanthroline, [Co(phen)33+] as the indicator of hybridization reaction.
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