Figure 1. Photocleavable copolymers are used to prepare nanoparticles with inducible precipitation.

(a) Photocleavable PEG-b-PLA copolymers can be synthesized using a photolabile linker. (b) The light-induced cleavage of the polymer into smaller chains can be followed by gel permeation chromatography. (c) Nanoparticles can be prepared using different ratios of photocleavable to non-cleavable copolymers. On ultraviolet irradiation, these core-shell nanoparticles lose their PEG corona proportionally to the content of photocleavable copolymer. (d) Nanoparticles prepared with photocleavable copolymer can be rapidly and efficiently precipitated in the presence of CaCl₂ by ultraviolet irradiation. Values represent mean±s.d., n=3.