Nano-biosensor for the in vitro lactate detection using bi-functionalized conducting polymer/N, S-doped carbon; the effect of αCHC inhibitor on lactate level in cancer cell lines

A robust amperometric sensor was developed for the lactate detection in the extracellular matrix of cancer cells. The sensor was fabricated by separately immobilizing nicotinamide adenine dinucleotide (NAD+) onto a carboxylic acid group and lactate dehydrogenase (LDH) onto an amine group of bi-functionalized conducting polymer (poly 3-(((2,2':5′,2″-terthiophen)-3′-yl)-5-aminobenzoic acid (pTTABA)) composited with N, S-doped porous carbon. Morphological features of the composite layer and sensor performance were investigated using FE-SEM, XPS, and electrochemical methods. The experimental parameters were optimized to get the best results. The calibration plot showed a linear dynamic range between 0.5 μM and 4.0 mM with the detection limit of 112 ± 0.02 nM. The proposed sensor was applied to detect lactate in a non-cancerous (Vero) and two cancer (MCF-7 and HeLa) cell lines. Among these cell lines, MCF-7 was mostly affected by the administration of lactate transport inhibitor, α-cyano-4-hydroxycinnamate (αCHC), followed by HeLa and Vero, respectively. Furthermore, the effect of αCHC concentration and treatment time on the lactate level in the cell lines were demonstrated. Finally, cytotoxicity studies were also performed to evaluate the effect of αCHC on cell viability. •NAD+ and LDH were separately immobilized on the bi-functionalized conducting polymer layer.•Lactate was selectively detected in the extracellular matrix of non-cancerous and cancerous cells.•Sensor performance was compared between N, S doped porous carbon and other carbon materials.•The effect of αCHC inhibitor concentration and treatment time on the lactate level in cell lines was analyzed.