Fabrication of Enzyme-Free and Rapid Electrochemical Detection of Glucose Sensor Based on ZnO Rod and Ru Doped Carbon Nitride Modified Gold Transducer

Over 3 in 4 adults with diabetes live in low- and middle-income counties and health expenditure also increased 316% over the last 15 years. In this regard, we fabricate low cost, reusable and rapid detection of diabetes sensor based on zinc oxide rod inserted ruthenium-doped carbon nitride (ZnO–g–Ru–C3N4) modified sensor device. Developed sensor device physically and electrochemically characterized using X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV). Sensing device as an effective enzyme-free glucose detection with high sensitivity (346 μA/mM/cm2) over the applied lower potential of +0.26 V (vs. Ag/AgCl), fast response (3 s) and broad linear range of (2–28) mM, coupled with a lower limit of detection (3.5 nM). The biosensing device gives better anti-interference ability with justifiable reproducibility, reusability (single electrode re-use 26 times in physiological buffer and 3 times in serum) and stability. Moreover, the real-time applicability of the sensor device was evaluated in human blood, serum and urine samples

Highly selective and real-time detection of 5-hydroxymethylcytosine in genomic DNA using a carbon nitride-modified gold transducer-based electrochemical sensor

Cancer biomarkers are crucial indicators of cancer status and progression that aid in early detection and more effective treatment of the disease. The loss of 5-hydroxymethylcytosine (5hmC), an oxidation product of 5-methylcytosine (5mC), is a recurrent epigenetic biomarker across various types of cancers. Therefore, accurately quantifying 5hmC holds great potential for various clinical applications. However, distinguishing 5hmC from 5mC using conventional methods is challenging. In this study, we developed a rapid and highly selective electrochemical sensor for label-free detection of 5hmC-enriched DNAs using a graphitic carbon nitride (g-C3N4)-modified gold transducer. Two-dimensional g-C3N4 sheets were synthesized via direct pyrolysis of urea under ambient or nitrogen atmospheres and drop-cast onto the gold electrode. Subsequently, 5hmC-containing DNAs were immobilized onto g-C3N4 via hydrogen bonding between the ???OH of 5hmC and the -NH2 of g-C3N4. The developed sensor demonstrated high sensitivity, selectivity, remarkable reproducibility, and stability, with a low oxidation potential (0.23 V) and an extremely low limit of detection (0.316 pM) for 5hmC. The sensor was also tested for its applicability to real samples using primary liver samples from mouse models, in which 5hmC levels were diminished due to either Tet gene knockout or hepatocellular carcinogenesis. The sensor effectively detected reduced genomic 5hmCs in TET-deficient livers and hepatocellular carcinomas compared to controls. Thus, this novel sensing strategy has the potential to develop clinically applicable sensors for early cancer diagnosis and prognosis evaluation by rapidly quantifying genomic 5hmC

Ultra selective label free electrochemical detection of cancer prognostic p53-antibody at DNA functionalized graphene

Detection of p53 antibody, a universal cancer biomarker, essential for the early diagnosis and prevention of cancer mortality. Here, we report label free electrochemical detection of p53 antibody binding with DNA on a graphene prepared by direct electrical exfoliation of pencil graphite in presence of aminoacid (glycine) in aqueous solution for the first time. Role of glycine in preventing graphitization is analysed using Fourier transform infrared spectroscopy, Raman, X-ray diffractommetry, X-ray photoelectron spectroscopy and transmission electron microscopy. Graphene has been decorated with gold nanoparticles prior to the biofunctionalization with DNA sequence, representing lung cancer, followed by its hybridization with a universal cancer biomarker anti-p53 antibody. Changes in the cyclic volatmetric and impedance signal of the graphene‑gold modified electrode upon the occurrence of molecular binding events is monitored in the presence of ferri/ferro cyanide redox probe. The binding of DNA antibody has been theoretically confirmed using bioinformatic tool. Selectivity of the sensor is demonstrated using anti p21 antibody and DNA sequences from E-Coli pathogen. The cancer biomarker antibody can be detected in the concentration range from 0.1 ng/L to 0.1 μg/L. The minimal concentration of dsDNA required for the efficient sensing of anti-p53 antibody is 0.6 fM. Both graphene preparation and cancer biomarker sensing methods are simple, rapid, easy to fabricate, stable and can be utilized for practical applications. Keywords: Electrical exfoliation, Graphene, DNA, p53 antibody, Selective, Label fre