On January 7, 2026, the MIX-UP team, jointly formed by Nanjing University of Technology and Nanjing Agricultural University, published a research paper titled "Solar-Biohybrid Upcycling of Polylactic Acid Plastics to Alanine" in Angewandte Chemie International Edition. Professor Qiu Bocheng from Nanjing Agricultural University, Associate Professor Zhou Jie from Nanjing University of Technology, and Professor Yan Cheng from East China University of Science and Technology were the corresponding authors. Doctor Xie Bin from Nanjing University of Technology was the first co-author of the paper. Professors Jiang Min and Dong Weiliang from the MIX-UP team provided guidance on the experimental design. This work was supported by the National Key Research and Development Program of China's Circular Economy Special Project (2024YFC3908300) and the Special Fund for Carbon Peak and Carbon Neutrality Innovation in Jiangsu Province (BT2025030).
This research developed a solar-biological hybrid system that can upgrade discarded polylactic acid (PLA) plastics into alanine under mild conditions. The research team developed a bio-chemical cascade catalytic strategy: Firstly, they utilized a peptide enzyme mutant that had been computationally assisted and modified. Under the conditions of 55°C and pH 10, this mutant was able to depolymerize the discarded commercial PLA straws and convert them into lactic acid, with a conversion rate of 92%. Subsequently, the hydrolyzed products were directly sent to the photocatalytic system. Under the irradiation of visible light, through a ZnIn2S4 catalyst loaded with nickel and using ammonia as the nitrogen source, lactic acid was further converted into high-value-added alanine.
This integrated system operates under normal temperature and pressure, with an alanine yield of up to 61.91 mmol·g⁻¹·h⁻¹ and a total yield of 60%. Further mechanism studies indicate that the reaction proceeds via an oxygen-centered free radical pathway, and nickel effectively promotes the separation of photogenerated carriers. Life cycle assessment shows that the carbon emissions of this series system are significantly lower than those of traditional thermal catalysis and single-step photocatalysis processes. This work not only provides a sustainable new path for the high-value utilization of PLA plastic waste, but also offers a new solution for achieving the green conversion of waste plastics to high-value-added chemicals under mild conditions.
