Vesicle Encapsulation of a Nonbiological Photochemical System Capable of Reducing NAD⁺ to NADH

One of the fundamental structures of a cell is the membrane. Self-assembling lipid bilayer vesicles can form the membrane of an artificial cell and could also have plausibly assembled prebiotically for the origin of life. Such cell-like structures, that encapsulate some basic subset of the functions of living cells, are important for research to infer the minimum chemistry necessary for a cell, to help understand the origin of life, and to allow the production of useful species in microscopic containers. We show that the encapsulation of TiO₂ particles has the potential to provide the basis for an energy transduction system inside vesicles which can be used to drive subsequent chemistry. TiO₂ encapsulated in vesicles can be used to produce biochemical species such as NADH. The NADH is formed from NAD⁺ reduction and is produced in a form that is able to drive further enzymatic chemistry. This allows us to link a mineral-based, nonbiological photosystem to biochemical reactions. This is a fundamental step toward being able to use this mineral photosystem in a protocell/artificial cell