Nanorg Microbial Factories: Light-Driven Renewable Biochemical Synthesis Using Quantum Dot-Bacteria Nanobiohybrids.

Living cells do not interface naturally with nanoscale materials, although such artificial organisms can have unprecedented multifunctional properties, like wireless activation of enzyme function using electromagnetic stimuli. Realizing such interfacing in a nanobiohybrid organism (or nanorg) requires (1) chemical coupling via affinity binding and self-assembly, (2) the energetic coupling between optoelectronic states of artificial materials with the cellular process, and (3) the design of appropriate interfaces ensuring biocompatibility. Here we show that seven different core-shell quantum dots (QDs), with excitations ranging from ultraviolet to near-infrared energies, couple with targeted enzyme sites in bacteria. When illuminated by light, these QDs drive the renewable production of different biofuels and chemicals using carbon-dioxide (CO2), water, and nitrogen (from air) as substrates. These QDs use their zinc-rich shell facets for affinity attachment to the proteins. Cysteine zwitterion ligands enable uptake through the cell, facilitating cell survival. Together, these nanorgs catalyze light-induced air-water-CO2 reduction with a high turnover number (TON) of ∼106-108 (mols of product per mol of cells) to biofuels like isopropanol (IPA), 2,3-butanediol (BDO), C11-C15 methyl ketones (MKs), and hydrogen (H2); and chemicals such as formic acid (FA), ammonia (NH3), ethylene (C2H4), and degradable bioplastics polyhydroxybutyrate (PHB). Therefore, these resting cells function as nanomicrobial factories powered by light.