Visible-light driven redox system of water-soluble zinc porphyrin and platinum nanoparticles for selective reduction of pyruvate to lactate
Lactate has received a great deal of attention as a raw material for biodegradable plastics. Lactate is synthesized by fermentative and chemical procedures. Using chemical procedure, lactate is synthesized industrially by reacting acetaldehyde with hydrogen cyanide, highly toxic substance, and hydrolysing the resultant lactonitrile. In this study, a selective pyruvate reduction to lactate using a visible light-driven redox system consisting of water-soluble zinc porphyrin as a photosensitizer, methylviologen as an electron mediator and poly(vinylpyrrolidone) dispersed platinum nanoparticles (Pt-PVP) as a catalyst as a new lactate production method without toxic substance is developed. By using this redox system, the reduction efficiency of pyruvate to lactate was achieved up to 40 % with visible light irradiation for 24 h. Furthermore, it was found that the addition of zinc acetate (up to c.a. 13.5 % of the initial concentration of pyruvate) to this photoredox system promoted lactate production due to the pyruvate reduction.