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

Abstract

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 nano-biohybrid 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 coreshell 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 (CO 2 ), 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-CO 2 reduction with a high turnover

Material–Microbe Interfaces for Solar-Driven CO2 Bioelectrosynthesis

“…In the year 2019 CO 2 photoreduction to CH 4 and CO was achieved via a semiartificial photosynthetic system [59]. In the same year, a living quantum dot (QD) bacterial hybrid was constructed through the self-assembly of biocompatible QD and specific enzymes inside the living cells [62]. See [30][31][32]41,[52][53][54][55][56]63,68,70].…”

“…A living quantum dot bacterial hybrid was constructed through the self-assembly of biocompatible quantum dots and specific enzymes inside the living cells (Box 2) [62]. Such hybrid systems can be used as synthetic biological tools where the direct activation of the enzyme by light can trigger the synthesis of fuels and chemicals from CO 2 with a higher QE ( Figure 3D).…”

“…Intercellular photosensitization is a process in which light-harvesting semiconducting quantum dots are passively inserted into a living cell. These harvesters attach themselves to desired proteins or enzymes by self-assembly and match their electrochemical potential so that they can be triggered by external electromagnetic radiation [62]. Using a specific wavelength of light, the enzymes can be induced to synthesize desired chemicals from CO 2 .…”

Gold nanoclusters cause selective light-driven biochemical catalysis in living nano-biohybrid organisms

“…Since nitrogenase is extremely sensitive to oxygen and is normally protected inside living cells, loss of cell viability could render the complete or partial loss of enzyme activity if rendered in air. 4,10,26,27 In order to verify this and correlate the cell viability with product yield, we compared the photocatalytic ammonia turnover number carried out in air (contains dinitrogen and dioxygen) and pure dinitrogen (oxygen-free). Using respective ammonia yield performed in pure dinitrogen as a reference, no change of ammonia production was observed in air with nanorgs made from Au 22 NCs, while the ammonia turnover number with Au 18 NCs decreased to 30% of the yield in dinitrogen (Fig.…”

“…Inorganic catalysts can directly utilize sunlight for photocatalytic conversion at high efficiencies, but suffers from lack of specicity. [1][2][3] Recently, nano-biohybrid catalysts have been suggested as an alternative, to combine the best properties of high turnover, efficiency, and selectivity, in a single biocatalyst both using in vitro [4][5][6][7] and in vivo [8][9][10] studies.…”