Electron Transfer from Semiconductor Nanocrystals to Redox Enzymes

Abstract

This review summarizes progress in understanding electron transfer from photoexcited nanocrystals to redox enzymes. The combination of the light-harvesting properties of nanocrystals and the catalytic properties of redox enzymes has emerged as a versatile platform to drive a variety of enzyme-catalyzed reactions with light. Transfer of a photoexcited charge from a nanocrystal to an enzyme is a critical first step for these reactions. This process has been studied in depth in systems that combine Cd-chalcogenide nanocrystals with hydrogenases. The two components can be assembled in close proximity to enable direct interfacial electron transfer or integrated with redox mediators to transport charges. Time-resolved spectroscopy and kinetic modeling have been used to measure the rates and efficiencies of the electron transfer. Electron transfer has been described within the framework of Marcus theory, providing insights into the factors that can be used to control the photochemical activity of these biohybrid systems. The range of potential applications and reactions that can be achieved using nanocrystal–enzyme systems is expanding, and numerous fundamental and practical questions remain to be addressed.

Electroenzymatic Nitrogen Fixation Using a MoFe Protein System Immobilized in an Organic Redox Polymer

“…This enabled the investigation of the direct electrochemical kinetics for each of the cofactors in nitrogenase under biologically relevant conditions. [11] Electron tunneling theory suggests that direct electron transfer requires the correct orientation between the electron donor and the acceptor within 14 distance for efficient electron tunneling, [12,13] enabling electron transfer to be faster than the enzymatic reaction, thus promoting superior performance. [11,14] Accordingly, the measured bioelectrocatalytic current is solely due to the enzyme attached as a protein monolayer within the electron tunneling distance.…”

Influence of Surface Ligands on Charge-Carrier Trapping and Relaxation in Water-Soluble CdSe@CdS Nanorods

“…Similar approaches might be applicable to increase order in the ligand sphere of PEG-ligand systems, resulting in less surface electron traps. As electron trapping occurs on a nanosecond and slower timescale, these become in particular important when coupling NR to molecular catalysts such as hydrogenases, where electron transfer to the catalytic center occurs on a tens of nanosecond timescale [79] and trapping of electrons can block the transfer to a catalytic reaction center [80].…”

Biomolecule‐Directed Carbon Nanotube Self‐Assembly

“…Biohybrid materials combine biomolecules and synthetic functional materials, [1][2][3] such as nanoparticles, [4][5][6] polymers, [7,8] or small molecules. [9,10] Interest in biohybrids research has grown rapidly over the past decades, bridging the fields of chemistry, physics, materials science, nanoscience, biology, and medicine.…”