Poly(Alizarin Red S) on pyrolytic graphite electrodes as a new multi-electronic system for sensing oxandrolone in urine.

This study presents a new polymeric and multielectronic system, the poly-Alizarin Red S (PARS), obtained from the electropolymerization of Alizarin Red S (ARS) dye on an edge-plane pyrolytic graphite electrode (EPPGE) surface. During EPPGE/PARS electrochemical characterization, we identified seven stable and reversible redox peaks in acidic medium (0.10 mol L-1, pH 1.62 KH2PO4), which indicated its mechanisms underlying electropolymerization and electrochemical behavior. To the best of our knowledge, this is the first study to use an EPPGE/PARS electrode to detect oxandrolone (OXA) in artificial urine, where PARS acts as a synthetic receptor for OXA. The interactions of OXA with EPPGE/PARS as well as the properties of PARS were investigated using density functional theory (DFT). Atomic force microscopy (AFM) was used to characterize EPPGE/PARS, and it was found that the PARS polymer formed a semi-globular phase on the EPPGE surface. The limit of detection for OXA found by the sensor was close to 0.50 nmol L-1, with a recovery rate of approximately 100% in artificial urine. In addition to the application proposed in this study, EPPGE/PARS is a low-cost product that could be applied in several devices and processes, such as supercapacitors and electrocatalysis.

Development of cashew gum-based bionanocomposite as a platform for electrochemical trials.

Cashew gum (CG) biopolymer is from natural source, biocompatible, non-toxic, inexpensive, and easily extracted from the exudate of the Anacardium occidentale L. tree, which is abundant in the north and northeast of Brazil. Prussian blue nanoparticles (PBNPs) can be embedded in the natural materials and have been used in several (bio)technological applications. This work presents a new cashew gum-based bionanocomposite containing PBNPs prepared in situ (PBNPs@GC), where the CG biopolymer was used as a matrix to prevent nanoparticles aggregation. Herein, investigate the effect of different CG concentrations about the bionanocomposite properties, and demonstrated it use as potential electrochemical sensor for drugs trials. The PBNPs@CG were characterized using UV-Vis, FTIR, XRD, DLS, zeta potential, TEM and cyclic voltammetry. The CG proved to be a suitable host for the PBNPs synthetized. These PBNPs were spherical, crystalline, stable, with a size of 5.0-15.0 nm, and without agglomeration. The bionanocomposite electrochemical behavior shown their ability to the oxidize some drugs, such as metamizole (MTM), acetaminophen (ACT) and methotrexate (MTX). These results demonstrated the innovative character of these bionanocomposite and encourage their further exploration for applications in nanobiomedicine like electrochemical (bio)sensors.

Development of a low-cost electrochemical sensor based on babassu mesocarp (Orbignya phalerata) immobilized on a flexible gold electrode for applications in sensors for 5-fluorouracil chemotherapeutics.

There are increasing concerns regarding the risks arising from the contamination of manipulators of antineoplastic drugs promoted by occupational exposure or even in the dosage of drugs. The present work proposes the use of an electrochemical sensor based on a biopolymer extracted from the babassu coconut (Orbignya phalerata) for the determination of an antineoplastic 5-fluorouracil (5-FU) drug as an alternative for the monitoring of these drugs. In order to reduce the cost of this sensor, a flexible gold electrode (FEAu) is proposed. The surface modification of FEAu was performed with the deposition of a casting film of the biopolymer extracted from the babassu mesocarp (BM) and modified with phthalic anhydride (BMPA). The electrochemical activity of the modified electrode was characterized by cyclic voltammetry (CV), and its morphology was observed by atomic force microscopy (AFM). The FEAu/BMPA showed a high sensitivity (8.8 µA/µmol/L) and low limit of detection (0.34 µmol/L) for the 5-FU drug in an acid medium. Electrochemical sensors developed from the babassu mesocarp may be a viable alternative for the monitoring of the 5-FU antineoplastic in pharmaceutical formulations, because in addition to being sensitive to this drug, they are constructed of a natural polymer, renewable, and abundant in nature. Graphical abstract ᅟ.