GdTiO3 perovskite modified graphene composite for electrochemical simultaneous sensing of Acetaminophen and Dopamine

A novel electrochemical biosensor was developed using GdTiO3 (GTO) perovskite prepared by sol-ge l(S) and hydrothermal (H) methods and decorated on few layered graphene for simultaneous sensing and quantification of dopamine (DA) and acetaminophen (ACE). The physical and structural characterization of the perovskites and composites were done using XRD, Raman, FTIR, XPS, and TEM analysis. Electrochemical characterization indicates higher activity for the GTO(S)-Gr composite modified electrode than the individual graphene, GTO(S) and GTO(H) component modified electrodes towards DA and ACE sensing. Simultaneous sensing in physiological buffer under optimized conditions exhibited wide linear ranges from 72 nM to 1.5 mu M with lowest detection limit (LOD) 96.89 nM for DA and 50 nM to 1.5 mu M with LOD 58.85 nM for ACE. The estimated sensitivity values are 3.357 x 10(-5) A/nM and 2.177 x 10(-5) A/nM, respectively for DA and ACE being higher than that of the literature reported for the graphene based metal oxide and perovskite sensors. The sensor showed high selectivity towards DA and ACE in the presence of co-interfering components like ascorbic acid, uric acid which may oxidize at the same potential. The binary composite was validated for DA and ACE sensing in practical applications using blood serum, tablet and urine samples and observed good signal recovery. The fabricated sensor was stable and showed good reproducibility. (C) 2021 Elsevier B.V. All rights reserved.11Nsciescopu

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

Single step sol-gel synthesized Mn2O3-TiO2 decorated graphene for the rapid and selective ultra sensitive electrochemical sensing of dopamine

Single step sol-gel synthesized TiO2 and Mn2O3 decorating the pristine graphene (Gr) and graphene oxide (GO), by traditional physical mixing, for selective dopamine (DA) sensing in the presence of its potential interferences in PBS buffer (pH 5). Resulted binary and ternary composites were characterized by XRD, FTIR, UV-DRS, Raman, FE-SEM and TEM techniques. The ternary (TiO2-Mn2O3-Gr (TMGr)) composite showed higher electrochemical activities compared to the binary (TiO2-Gr (TGr), Mn2O3-Gr (MGr) and TiO2-Mn2O3 (TM)) composite in the presence of K-3[Fe(CN)(6)]/K-4[Fe(CN)(6)] redox probe. The same was observed for dopamine (DA) sensing at pH 5. Due to the presence of intrinsic (hydroxyl, acid and epoxide) functional groups with lesser sp(2) hybridized carbon network, the GO-metal oxide composites showed poor electrochemical activity than the Gr-metal oxide composite. Concentration studies by differential pulse voltammetry (DPV) revealed a wide linear range from 0.02 to 100 nM with the lowest detection limit 0.026 nM. The ternary composite was validated for DA sensing by injecting commercial dopamine into the blood serum and urine samples and observed >= 98% signal recovery. The developed sensor showed good stability and reproducibility. (C) 2019 Elsevier Ltd. All rights reserved.11Nsciescopu

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

Carbon dots stabilized silver-lipid nano hybrids for sensitive label free DNA detection

Carbon dots have been extensively used for the development of fluorescent based molecular affinity sensors. However, label free DNA sensing by electrochemical method is not reported so far. Herein, we report carbon dots stabilized silver nanoparticles (CD-AgNPs) lipid nano hybrids as a sensitive and selective platform for label free electrochemical DNA sensing. The CD-AgNPs were synthesized by wet chemical method and then characterized by UV-visible, Fourier-transform Infra-red (FT-IR), dynamic light scattering (DLS) and high resolution transmission electron microscopy (HR-TEM) techniques. These CD-AgNPs were used for decorating the binary lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and N-[1-(2,3-Dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTAP) surface (named as lipid) and tethered on self-assembled monolayer of 3-mercaptopropionic acid (MPA) (MPA-lipid-CD-AgNPs). The formation of array of MPA-lipid-CD-AgNPs on Au electrode was confirmed by atomic force microscopy (AFM). Electrochemical behavior of MPA- lipid-CD-AgNPs was monitored in the presence of 1 mM potassium ferri/ferrocyanide (K-3/K-4 [Fe(CN)(6)]). The formation of layer-by-layer MPA-lipid-CD-AgNPs is indicated by increased anodic and cathodic peak (Delta E-p) separation with decreased redox peak current of K-3/K-4 [Fe(CN)(6)]. Short chain DNA (30 mer oligonucleotide, representing the lung cancer) was used as a model system for label free DNA sensing. Un-hybridized (single stranded DNA), hybridized (complementary hybridized), single, double and triple base mismatched target DNA hybridized surfaces were efficiently discriminated at 1 mu M target DNA concentration at the Au/MPA-lipid-CD-AgNPs electrode by change in the charge transfer resistance from impedance technique. Further, the modified electrode was successfully used to determine target DNA in a wide linear range from 10(-16) to 10(-11) M. The present work open doors for the utilization of CDs in molecular affinity based electrochemical sensor design and development.11Nsciescopu