Panchromatic Polymer Dot-Bacteria Biohybrid Systems for Photosynthetic CO₂ Reduction into Acetic Acid.

Abstract

Enabling the nonphotosynthetic bacterium <i>Moorella thermoacetica</i> (<i>M. thermoacetica</i>) to form a photosynthetic biohybrid system could transform carbon dioxide (CO₂) into value-added products. However, to ensure an efficient, mechanistic electron-transfer pathway to microbial catalysts, a pivotal nanoplatform that involves multicomponent composite systems for photoexcited electron transfer from the photosensitizer to the bacteria, as well as for enhancing light-harvesting capabilities and efficient electron/hole separation, is crucial. Here, we design panchromatic ternary polymer dots (Pdots) as biocompatible photosensitizers that can broaden the light absorption spectrum up to 800 nm and enhance light utilization due to efficient charge and energy transfer within the Pdots. By matching the energy level of Pdots to the positions of the redox mediators in <i>M. thermoacetica</i>, effective photoexcited electron transfer to the bacterial membrane proteins can be achieved, providing a sufficient driving force to enhance the efficiency of acetate production. The optimal system renders a photobiocatalytic performance of acetic acid production up to 1.6 mM, corresponding to 320 mmol/g_Pdots after a 3 day experiment at a light intensity of 5 mW cm^-2.