Rong Tong, Houman D. Hemmati, Robert Langer, and Daniel S. Kohane
Journal of the American Chemical Society 2012 134 (21), 8848-8855
This drug delivery system utilizes a "photo-switchable" nano-particle composed of an outer layer of hybrid spyropyran-lipid-PEG chains and in inner core of photo-releasable drug molecules . When irradiated under UV light, spyropryan reversibly isomerizes in a way that causes the volume of the nanoparticle to contract. This contraction is hypothesized to enhance tumor penetration to make for a more effectively delivered drug that can be "repetitively dosed from a single administration."