Gold nanoparticles decorated kaolinite mineral modified screen-printed electrode: Use for simple, sensitive determination of gallic acid in food samples.

The current study offers the nanomolar quantification of gallic acid (GAL) based on gold nanoparticles (AuNps) and kaolinite minerals (KNT) modified on a screen-printed electrode (SPE). The electrochemical behavior of GAL was performed using differential pulse voltammetry (DPV) in Britton Robinson (BR) buffer solution at pH 2.0 as a supporting electrolyte. Under the optimized DPV mode parameters, the oxidation peak current of GAL (at 0.72 V vs Ag/AgCl) increased linearly in the range between 0.002 µmolL-1 and 40.0 µmolL-1 with a detection limit of 0.50 nmolL-1. The effect of common interfering agents was also investigated. Finally, the applicability of the proposed method was verified by quantification analysis of GAL in black tea and pomegranate juice samples.

The development of electrochemical DNA biosensor based on poly-l-methionine and bimetallic AuPt nanoparticles coating: Picomolar detection of Imatinib and Erlotinib.

We report on the preparation of a new and simple electrochemical DNA biosensor based on DNA/AuPt/p-L-Met coating on a screen-printed carbon electrode (SPE) and its use in the determination of the cancer therapy agents, Imatinib (IMA) and Erlotinib (ERL). Poly-l-methionine (p-L-Met), gold, and platinum nanoparticles (AuPt) were successfully coated by one-step electrodeposition onto the SPE from a solution containing L-Met, HAuCl4, and H2PtCl6. The immobilization of DNA was achieved by drop-casting on the surface of the modified electrode. Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), Field-Emission Scanning Electron Microscopy (FE-SEM), Energy-Dispersive X-ray Spectroscopy (EDX), and Atomic Force Microscopy (AFM) were used to investigate the morphology, the structure, and the electrochemical performance of the sensor. Experimental factors influencing the coating and DNA immobilization processes were optimized. The peak currents originating from guanine (G) and adenine (A) oxidation of ds-DNA were used as signals to quantify IMA and ERL in the concentration range 2.33-80 nM and 0.032-1.0 nM with the LODs of 0.18 nM and 0.009 nM, respectively. The biosensor developed was suitable for determining IMA and ERL in human serum and pharmaceutical samples.

Four-way parallel factor analysis of voltammetric four-way dataset for monitoring the etoposide-DNA interaction with its binding constant determination.

In this paper, a novel strategy in the application of the parallel factor analysis (PARAFAC) to a four-way voltammetric dataset was improved to evidence the interaction of etoposide (ETO) and calf thymus deoxyribonucleic acid (DNA) to determine the ETO-DNA binding constant. PARAFAC is one of the most commonly used techniques applicable to the decomposition of higher-order data arrays to focus on features of interest and provides a different resolution of the chemical problem of interest. Under optimized conditions, peak current data of a seven-sample set containing DNA in the range of 2.0-90.0 µM in the presence of ETO at a constant concentration (10 µM) at five different pHs were recorded as a function of potential and frequency and then arranged as a four-dimensional array. The characteristic curves of ETO and ETO-DNA complex were monitored from the potential, frequency, pH, and DNA concentration profiles obtained by PARAFAC decomposition of the fourth-order array. The binding constant, which is one of the principal parameters for the estimation of drug-DNA interaction and mechanism, was computed from the DNA concentration profile. The consequence of drug-DNA binding constant (K = 1.26 × 106) indicated that there was a significant interaction between ETO and DNA with the intercalation mechanism.