ABSTRACT
A novel electrochemical sensor was developed for the detection of salivary cortisol levels. The sensor employs a combination of a molecularly imprinted polymer (MIP) and gold nanoparticles (AuNPs) that are electrodeposited onto a screen-printed electrode (SPE). The study utilised density functional theory and molecular docking techniques to determine the geometry of molecular orbitals, electrostatic potential energies, and binding energy of cortisol and the polymers. The thin film of cortisol-imprinted polymer on the SPE was created by electro-polymerizing pyrrole and thiophene-3-carboxylic acid on the electrode surface along with cortisol as the template molecule. The MIP film was characterised using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and electrochemical techniques. The sensor exhibited a linear response in the concentration range of 0.05 nmol L-1 to 2.5 µmol L-1, with a limit of detection of 0.01 nmol L-1, as determined by differential pulse voltammetry. This method offers a simple yet efficient and sensitive approach to detecting cortisol levels in human saliva samples.
Subject(s)
Metal Nanoparticles , Molecular Imprinting , Humans , Molecularly Imprinted Polymers , Gold/chemistry , Hydrocortisone , Molecular Imprinting/methods , Molecular Docking Simulation , Metal Nanoparticles/chemistry , Polymers/chemistry , Electrochemical Techniques/methods , Electrodes , Limit of DetectionABSTRACT
Bisphenol A (BPA) contamination from food packaging material has been a major concern in recent years, due to its potential endocrine-disrupting effects on humans, especially infants and children. This paper reports the detection of BPA using an electrochemical sensor based on molecularly imprinted polymer (MIP). Electrochemically reduced graphene oxide coated glassy carbon electrode used for this study. Density functional theory (DFT) at B3LYP/6-31 + G (d,p) level was used to calculate the molecular-level interaction between BPA and MIP. The pyrrole electrochemically polymerized in the presence of template molecule BPA on the electrode surface. BPA imprinted cavities were formed by removing entrapped BPA molecules from the polypyrrole film. MIP electrode was used for the determination of BPA in standard and real samples by differential pulse voltammetry. The peak current shows the linear relationship to the logarithmic concentration of BPA between 750 and 0.5 nmolL-1 with a correlation coefficient, R2 = 0.992. The limit of detection was found to be 0.2 nmolL-1 (S/N = 3). The reproducibility and repeatability of the sensor were also studied.
Subject(s)
Endocrine Disruptors , Molecular Imprinting , Animals , Benzhydryl Compounds , Cattle , Child , Electrochemical Techniques , Electrodes , Humans , Limit of Detection , Milk , Molecularly Imprinted Polymers , Phenols , Polymers , Pyrroles , Reproducibility of ResultsABSTRACT
Metal organic frameworks (MOFs) are excellent materials for energy storage and conversion. This report describes 2D metal-organic framework nanosheets as an electrocatalyst for the oxygen evolution reaction (OER) under alkaline conditions. An ultrathin nanosheet array of a NiCo-metal-organic framework was grown on nickel foam (NiCo-MOF/NF) by a one-step solvothermal method. The catalytic OER of the NiCO-MOF/NF electrode was analysed by electrochemical methods. The resulting NiCO-MOF/NF exhibited a high current density (50 mA cm-2) with an overpotential of 270 mV, a Tafel slope of 35.4 mV dec-1 and a high turnover frequency (TOF) of 0.68 s-1 (η = 0.27 V) towards the OER. The excellent catalytic activity of the MOF towards the OER was due to the two-dimensional nanosheet array of NiCo-MOF with plentiful accessible molecular active sites and excellent mass transport properties. Faster electron transport was also achieved due to the synergetic effect of Co and Ni present on the MOF.