Screen-printing of nanocube-based flexible microchips for the precise biosensing of ethanol during fermentation

The real-time and full concentration analysis of ethanol during the fermentation reaction allows the precise control of the microbial metabolism to promote the conversion rate; however, only few techniques can directly detect the fermentation broth without pretreatment. To address this issue, a screen-printed biosensing microchip (SPBM) was proposed to analyze the ethanol concentration in fermentation, relying on designing a well-defined nanocubic structure of an Au nanoparticles/nickel hexacyanoferrate nanocomposite. This nanocomposite was then made into a printing ink for the direct fabrication of a SPBM. The as-prepared microchip exhibits an ultrahigh electrocatalysis on nicotinamide adenine dinucleotide with a high sensitivity of 96.2 ± 2.9 μA·mM⁻¹·cm⁻². Moreover, after the immobilization of alcohol dehydrogenase, the accurate and rapid monitoring of the ethanol concentration during the real fermentation reaction can be realized within an ultrawide linear range of 0.1–10 M in the broth without any pretreatment.