Surface Modification of Biochar to Prepare Environmentally Friendly Electrochemical Biosensors for Detection of Cardiac Troponin T.

Driven by the need to investigate enhanced biosensing properties alongside the development of low-toxicity, economical, eco-friendly, and sustainable materials, this work explores the functionalization of biochara carbon-based materialand its subsequent anchoring onto the working electrode for the detection of cardiac troponin T (cTnT). Here, we discuss the interaction between biochar and glutaraldehyde at various concentrations, aiming to elucidate the relationship between the formation of full acetals and hemiacetals. It first allows an understanding of the cross-link reactions between glutaraldehyde and biochar and then better anchoring with the Cystamine-Au working electrode of a printed circuit board (PCB). These aspects improve the biosensor's stability and the cTnT antibody's specific adsorption. Electrochemical, AFM, Fluorescence Confocal, SEM, and FTIR analyses were employed to identify the optimal glutaraldehyde concentration that maximizes hemiacetal group formation, critical for stability to the electrode and the specific adsorption of the antibody. The resulting label-free, direct electrochemical cTnT immunosensor showed high sensitivity and selectivity, with a detection capacity of 0.01-5.00 ng·mL and a Limit of Detection (LOD) of 0.003 ng·mL, as determined by cyclic voltammetry. An additional advantage is the reusability of the PCB, which can be recycled at least twice by replacing the biochar layer on the working electrode, assigning an environmentally friendly characteristic to the immunoassay.