Photoluminescence quenching of silicon nanoparticles in phospholipid vesicle bilayers

Due to its unique optical properties, nanostructured silicon is a promising material for optoelectronic applications, solar energy conversion and chemical sensors. This paper demonstrates the incorporation of organic-capped silicon nanoparticles into the hydrophobic interior of phospholipid vesicle bilayers, and uses photoluminescence quenching to determine the accessibility of membrane-embedded nanoparticles to aqueous and lipid-bound quenchers. Experiments with water-soluble quenchers indicate the existence of two populations of membrane-bound nanoparticles with varying accessibilities to the aqueous phase. Results from membrane-bound quenchers reveal that the major population localizes deep inside the bilayer. The ability of the nanoparticles to fully embed in the bilayer allows studies of their interactions with both aqueous and lipophilic molecules in a biomimetic environment. These composites may prove useful in the development of aqueous-based sensors and provide a model system for studying nanoparticle/cell interactions.