Sensitivity Control of Label‐free DNA Hybridization Detection Based on Poly(thionine)‐Modified Glassy Carbon and Gold Electrodes

Abstract

Poly(thionine) (PTH)‐modified glassy carbon (PTH‐S/GCE and PTH‐D/GCE) and gold (PTH‐S/Au) electrodes were prepared for the label‐free detection of DNA hybridizations and their performances in terms of sensitivity and selectivity were compared. Single‐strand probe DNA (pDNA) was immobilized on the PTH films via covalent bonding between the amine (−NH2) group of PTH and the phosphate (PO43−) group at the 5' end of the pDNA. The PTH oxidation current was decreased because of the increase in the stiffness of PTH films. The current was further decreased after the duplex was formed by the hybridization of the target complementary DNA (cDNA). The pDNA/PTH‐S/GCE, pDNA/PTH‐D/GCE, and pDNA/PTH‐S/Au sensors showed excellent sensitivities of ca. 2.1, 55, and 1.9 μA/cm2/nM, respectively, and the detection limits (S/N = 3) were ca. 40.6, 1.5, and 45 pM, respectively, for the hybridization of target cDNA.

Progress in Electrochemical Biosensing of SARS-CoV-2 Virus for COVID-19 Management

“…Single-strand capture or probe NA (ss-NA) can bind with the target complementary NA (c-NA) that forms the basis of gene chips, DNA computers, and NA biosensors [22,42,43]. The hybridization between the probe ss-NA and target c-NA converts the recognition event into a measurable electrical signal.…”

“…Antibody capture probe-based electrochemical biosensors or immunosensors display high specificity and reliability for the detection of target biomolecules [43]. Accordingly, anti-SARS-CoV-2 capture probe-based immunosensors have received potential interest for screening SARS-CoV-2 protein antigens.…”

“…Even if antibody capture probes exhibit high specificity, several limitations of antibodies, such as low stability, high cost, short shelf-life, and immunogenicity prompted to use of alternative capture probes for the development of biosensors and other biological applications [43,51]. The aptamer is one of the suitable alternatives to antibodies that can overcome the intrinsic limitations of immunosensors.…”

“…Thus, aptamers have attracted wide interest in developing electrochemical biosensors to detect various target biomolecules [43,51,52]. Idili et al prepared a label-based electrochemical aptasensor for the detection of SARS-CoV-2 SP that is based on an Au electrode modified with methylene blue derivative (MB2) labeled aptamer (Figure 5b) [72].…”

The Implications of Fragmented Genomic DNA Size Range on the Hybridization Efficiency in NanoGene Assay

“…Essentially, it is the formation of a hydrogen bond between complementary sequences of probe single-stranded DNA (ssDNA) and the target ssDNA. It is employed widely in numerous bioassays, such as membrane hybridization [ 1 , 2 , 3 ], fluorescence in situ hybridization (FISH) [ 4 , 5 , 6 , 7 ], microarray hybridization [ 8 , 9 , 10 , 11 ], and electrochemical DNA assays [ 12 , 13 , 14 , 15 ]. It is also used in magnetic beads and the quantum dots-based NanoGene assay [ 16 , 17 ].…”