Lai Y.-HLim J.-CLee Y.-CJIAN-JANG HUANG2022-04-252022-04-25202124701343https://www.scopus.com/inward/record.uri?eid=2-s2.0-85105038110&doi=10.1021%2facsomega.1c00222&partnerID=40&md5=db42cdcc334b798761ff1bfb4992ec93https://scholars.lib.ntu.edu.tw/handle/123456789/607192Traditional methods of monitoring biochemical reactions measure certain detectable reagents or products while assuming that the undetectable species follow the stoichiometry of the reactions. Here, based upon the metal-oxide thin-film transistor (TFT) biosensor, we develop a real-time molecular diffusion model to benchmark the concentration of the reagents and products. Using the nicotinamide adenine dinucleotide (NADH)-oxaloacetic acid with the enzyme of malate dehydrogenase as an example, mixtures of different reagent concentrations were characterized to extract the ratio of remaining concentrations between NAD+ and NADH. We can thus obtain the apparent equilibrium constant of the reaction, (8.06 ± 0.61) × 104. Because the whole analysis was conducted using a TFT sensor fabricated using a semiconductor process, our approach has the advantages of exploring biochemical reaction kinetics in a massively parallel manner. ? 2021 The Authors. Published by American Chemical Society.journal article10.1021/acsomega.1c002222-s2.0-85105038110