Direct electrochemical behavior of cytochrome c on DNA modified glassy carbon electrode and its application to nitric oxide biosensor

Sensitive Electrochemical Biosensor for Rapid Screening of Tumor Biomarker TP53 Gene Mutation Hotspot

Rapid and sensitive detection of cancer biomarkers is crucial for cancer screening, early detection, and improving patient survival rate. The present study proposes an electrochemical gene-sensor capable of detecting tumor related TP53 gene mutation hotspots by self-assembly of sulfhydryl ended hairpin DNA probes tagged with methylene blue (MB) onto a gold electrode. By performing a hybridization reaction with the target DNA sequence, the gene-sensor can rearrange the probe's structure, resulting in significant electrochemical signal differences by differential pulse voltammetry. When the DNA biosensor is hybridized with 1 μM target DNA, the peak current response signal can decrease more than 60%, displaying high sensitivity and specificity for the TP53 gene. The biosensor achieved rapid and sensitive detection of the TP53 gene with a detection limit of 10 nmol L-1, and showed good specific recognition ability for single nucleotide polymorphism (SNP) and base sequence mismatches in the TP53 gene affecting residue 248 of the P53 protein. Moreover, the biosensor demonstrated good reproducibility, repeatability, operational stability, and anti-interference ability for target DNA molecule in the complex system of 50% fetal bovine serum. The proposed biosensor provides a powerful tool for the sensitive and specific detection of TP53 gene mutation hotspot sequences and could be used in clinical samples for early diagnosis and detection of cancer.

Electrochemical Sensor for Directional Recognition and Measurement of Antibiotic Resistance Genes in Water

The establishment of rapid targeted identification and analysis of antibiotic resistance genes (ARGs) is very important. In this study, an electrochemical sensor, which can detect ARGs was obtained by modifying the sulfhydryl single-stranded DNA probe onto the thin-film gold electrode through self-assembly. The sensor can perform a hybridization reaction with a target sequence to obtain an electrochemical impedance spectroscopy signal. The results showed that when the concentration of the probe used to modify thin-film gold electrodes during preparation was 1 μM, the hybridization time was 1 h, and the hybridization temperature was 35 °C, the self-assembled sensor showed good detection performance for the ARGs encoding β-lactam hydrolase. The measurement ARG concentration linear range is 6.3-900.0 ng/mL, and the R² is 0.9992. The sensor shows good specific recognition ability for single-base, double-base, and three-base mismatch DNA. In addition, after 30 days of storage at 4 °C, the accurate identification and analysis of ARGs can still be maintained.

New Disposable Nitric Oxide Sensor Fabrication Using GaN Nanowires

Gallium nitride (GaN) nanowires anchored on the surface of cost-effective pencil graphite electrodes (PGEs) have been developed as a new disposable nitric oxide (NO) sensor through a hydrothermal method followed by annealing treatment. The as-obtained nanomaterials were examined by field emission scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and EIS. Concurrently, the electrocatalytic performance has been analyzed using cyclic voltammetry and amperometric measurements. The experimental results exhibit good electrochemical sensing performance toward the generated NO in NO2 - with a wide linear detection range of 1.0 μM to 1.0 mM with a correlation coefficient of 0.999 and a detection limit of 0.180 μM. In addition, the GaN nanowire-modified PGE surface showed high selectivity for the detection of NO as compared to other relevant biomolecules. This confirms that the PGE/GaN nanowire is a new promising electrochemical sensor for the sensitive detection of NO.

Helix structure of the double-stranded DNA for aptameric biosensing and imaging of cytochrome c

Here, a method is introduced for construction the aptameric biosensor for biosensing detection of cytochrome C (CYC) based on chain-shape structure of aptasensor by using highly dispersed silver nanoparticles (AgNPs) on acid-oxidized carbon nanotube (CNTs) substrate. The animated capture probe (ssDNA1) and CYC-aptamer (ssDNA2) was immobilized on AgNPs/CNTs surface by covalent amide bonds formed by the carboxyl groups on the nanotubes and the amino groups on the oligonucleotides and hybridization, respectively. In this protocol, the nucleic acids at both ends of the ssDNA1 were sequenced to be complementary (tailor-made ssDNA1). The helix structure of the double-stranded DNA was fabricated by hybridizing ssDNA2 with its complementary sequence (ssDNA1). CYC-aptamer could be forced to dissociate from the sensing interface after CYC triggered structure switching of the aptamer and ssDNA1 thus tend to form a chain-shape structure through the hybridization of the complementary sequences at both its ends. The proposed assay permitted to detect CYC in the linear range of 0.01-750 nM with a very low limit of detection (LOD) (1.66 pM). In addition, the specificity of this sensing system for the detection of CYC was also demonstrated by using albumin, fructose, myoglobin, and hemoglobin.

Self-assembled AuNPs on sulphur-doped graphene: a dual and highly efficient electrochemical sensor for nitrite (NO2−) and nitric oxide (NO)

Gold nanoparticles self-assembled over sulphur-doped graphene as a reusable electrocatalyst for selective and sensitive quantification of NO₂⁻ and NO.