Visible-light driven redox system of water-soluble zinc porphyrin and platinum nanoparticles for selective reduction of pyruvate to lactate

Abstract

Lactate has received a great deal of attention as a raw material for biodegradable plastics. Lactate is synthesized by fermentation and chemical procedures. Using chemical procedures, lactate is synthesized industrially by reacting acetaldehyde with hydrogen cyanide, a 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 platinum nanoparticles dispersed on poly(vinylpyrrolidone)(Pt-PVP) as a catalyst, is developed as a new lactate production method without toxic substances. By using this redox system, a reduction efficiency of pyruvate to lactate of up to 40% was achieved with visible light irradiation for 24 h. Furthermore, it was found that the addition of zinc acetate (up to about 13.5% of the initial concentration of pyruvate) to this photoredox system promoted lactate production due to the pyruvate reduction.