Reaction of NiO film on flexible substrates with buffer solutions and application to flexible arrayed lactate biosensor

In this study, we proposed a flexible arrayed lactate biosensor based on pH-sensitive nickel oxide (NiO) films, and also investigated the adhesion between NiO film and different flexible substrates under reactions with different solutions. L-lactate dehydrogenase (LDH) and nicotinamide adenine dinucleotide (NAD+) were co-immobilized on pH-sensitive NiO film by using a crosslinking reagent, 3-glycidoxypropyltrimethoxysilane (GPTS). It was found that GPTS concentration would affect the sensing characteristics for the lactate biosensor. The lactate biosensor with 1:2 volume ratio of GPTS-toluene mixture had the best average sensitivity and linearity. In the range of lactate concentration from 0.2 mM to 3 mM, arrayed flexible lactate biosensor based on the NiO/PET structure had 38.218 mV/mM of average sensitivity. In addition, the average sensitivity of the sensor based on the NiO/Pt/PET structure was 32.483 mV/mM.