Design of imprinting matrix for dual template sensing via electropolymerized polythiophene films

Electrochemical Behavior of Glassy Carbon Electrodes Modified with Electropolymerized Film of N,N'-bis (2-thienylmethylene)-1,X-diaminobenzene toward Homovanillic Acid and 4-Hydroxyphenylacetic Acid

This study evaluates different electrochemical behaviors of modified glassy carbon electrodes (GCEs) for detecting urinary biomarkers related to breast cancer, namely homovanillic acid (HVA) and 4-hydroxyphenylacetic acid (4HPA). The analysis was performed in the presence of common urinary interferents, creatinine and urea. Modification of bare GCEs was done through the electropolymerization of N,N'-bis (2-thienylmethylene)-1,X-diaminobenzene (X = 2, 3, 4) isomers, so-called BTMD. The formation and characteristics of these polymeric layers were investigated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Differential pulse voltammetry (DPV) was used to measure responses of the electrodes  to HVA and 4HPA, assessing their sensitivity and selectivity. Results showed that the developed electrodes effectively detected both biomarkers, with peak currents increasing proportionally to biomarker concentrations and minimal interference from creatinine and urea. The modified electrodes exhibited better linearity at higher concentrations; however, saturation was observed for 4HPA at high concentrations with the p-BTMD/GCE. Each electrode displayed unique peak current, potential, and response profiles, highlighting their promise for cross-reactive sensing systems, such as electronic tongues, to analyze complex matrices such as urine.

Molecularly imprinted nanocomposites-based synthetic antibodies for uric acid-specific non-invasive electrochemical gout sensors

A disposable electrochemical sensor is introduced for the selective recognition of uric acid (UA), a crucial biomarker for gout arthritis. The sensor employs synthetic antibodies composed of molecularly imprinted polythiophene (MIP) laden graphitic carbon nitride (GCN) nanocomposites for the selective recognition of UA. Microscopic analysis demonstrates an increase in surface roughness and kurtosis after removing the template, indicating the fabrication and functionalization of the MIP/GCN sensors. These sensors exhibit excellent electrochemical properties, characterized by electrochemical impedance spectroscopy (EIS) and voltammetric (CV, DPV) methods. The sensor displays a wide linear detection range (1-500 µM), encompassing the normal UA levels in human saliva, high sensitivity (5.47 µA/cm2.µM), a low limit of detection (0.21 µM), and limit of quantification (0.64 µM). The sensor also exhibits low cross-sensitivity to common salivary interferences, including urea, creatinine, ascorbic acid, glucose, and glutamine. The MIP/GCN sensor accurately identifies UA in human saliva, resulting in a recovery of 93.25 ± 0.33%. Electrochemical studies, utilizing [Fe(CN)6]4-/3- as a redox probe, also provide insights into the mechanisms of interfacial redox reactions and selective UA recognition. This work demonstrates a significant improvement in POC testing, providing a reliable and non-invasive tool for gout diagnosis.