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

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

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