NADH Photoregeneration in a Fully Automated Microfluidic Setup

Enzyme catalysis is a powerful tool in chemical transformations, with the potential to aid the transition from fossil fuels to alternative energy carries. However, the application of enzymes is hindered by reduced cofactors' high cost. This work focuses on efficient cofactor regeneration, exploring a photochemical approach inspired by natural photosynthesis. Utilizing mixed valence Bi13S18Br2 nanocrystals as photoactive catalysts, triethanolamine (TEOA) was photo-oxidized to glycolaldehyde, crucial for beta-nicotinamide adenine dinucleotide (NAD(+)) reduction. Batch and microfluidic systems were employed, emphasizing the role of molecular oxygen in TEOA light-driven and auto-oxidation mechanisms. Indeed, the introduction of oxygen microbubbles in the microfluidic system significantly enhanced TEOA autocatalytic oxidative mechanism leading to a fivefold increase in NADH production compared to batch methods. To streamline the process and minimize operator intervention, a fully automated microfluidic system was designed, demonstrating excellent stability and reproducibility. This work provides a practical, automated, and scalable platform for real-world applications.