The resistance analysis related to the hepatitis B virus (HBV) genotyping and treatment procured key information for the study of infected patients. The aim of this study was to develop a novel assay for the voltammetric detection of DNA sequences related to the HBV genotype on the development of lamuvidine resistance by monitoring the oxidation signal of guanine. This new technique not only provides a rapid, cost-effective, simple analysis but also gives information concerning both genotyping and lamivudine resistance. Synthetic single-stranded oligonucleotides ("probe") including YMDD (HBV wild type) YVDD, or YIDD (mutations in the YMDD) variants have been immobilized onto pencil graphite electrodes with the adsorption at a controlled potential. The probes were hybridized with different concentrations of their complementary ("target") sequences such as synthetic complementary sequences, clonned PCR products, or real PCR samples. The formed synthetic hybrids on the electrode surface were evaluated by a differential pulse voltammetry technique using a label-free detection method. The oxidation signal of guanine was observed as a result of the specific hybridization between the probes and their synthetic targets and specific PCR products. The response of the hybridization of the probes with their single-base mismatch oligonucleotides at PGE was also detected. Control experiments using the noncomplementary oligonucleotides were performed to determine whether the DNA genosensor responds selectively. Numerous factors, affecting the probe immobilization, target hybridization, and nonspecific binding events, were optimized to maximize the sensitivity and reduce the assay time. Under the optimum conditions, 457 fmol/mL was found as the detection limit for target DNA. With the help of the appearance of the guanine signal, the new protocol is based on the electrochemical detection of HBV genotype for the development of lamuvidine resistance for the first time. Features of this protocol are discussed and optimized.

Serological evidence of previous HAV, HCV and HEV infections was not significantly different between Behçet's patients and other groups. However, previous HBV infection was found in a significantly lower number of BD patients as compared with healthy controls and systemic vasculitic patients.

In the presented study, a novel method is introduced that demonstrates the electrochemical detection of influenza B virus based on DNA hybridisation. The detection utilised gold nanoparticles (AuNPs) and Meldola's Blue (MDB), which is utilised as an intercalator label. The developed methodology, combined with a disposable pencil graphite electrode (PGE) and differential pulse voltammetry (DPV), was performed using both synthetic oligonucleotides and polymerase chain reaction (PCR) amplicons. The electrochemical oxidation response of guanine (approximately +0.1 V) and the voltammetric reduction signal of MDB (approximately À0.2 V) were measured before and after hybridisation reactions between a single strand DNA probe and its complementary target strain (synthetic target or denatured PCR samples). Before the immobilisation of the synthetic DNA probe of influenza type B virus, the transducer surface was interacted with AuNPs solution using a simple wet adsorption method. AuNP immobilisation was confirmed with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) to characterise the recognition surface of the genosensor. After the interaction between the PGE and AuNPs, a thiol-linked DNA probe was immobilised onto the nanoparticle-covered surface. When hybridisation occurred between the probe and its synthetic targets or specific PCR products, the highest MDB signal was observed. The probes were also challenged with equal quantities of non-complementary DNA at the PGE surface for the determination of biosensor selectivity. AuNP-coated electrodes showed high sensitivity and selectivity, specifically in real samples for the detection of the hybridisation reaction. The results obtained in the presented study indicated that the electrode surface area could be enhanced with AuNPs. The detection limit of the genosensor was found to be 54 picomoles for the synthetic target and 3.3 Â 10 7 molecules for the real samples (PCR) in 30 mL of sample volume. Future prospects and analytical performance of the sensor is briefly discussed.

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