Induced circular dichroism of merocyanine dye in the self-assembled polymeric nanoparticles

The core-shell type nanoparticles composed of poly(gamma-benzyl-L-glutamate) (PBLG) as hydrophobic inner core and poly(ethylene oxide) (PEO) as hydrophilic outer shell are formed from organic solution of the block copolymer by the diafiltration method. Amphiphilic merocyanine dyes (MDs) were self-assembled in the self-assembled copolymeric nanoparticles which provide a chiral microenvironment as red-shifted aggregates (J-aggregates). Also, the circular dichroism (CD) of MD was induced in the self-assembled copolymeric nanoparticles with negative and positive Cotton effect in the range of 575-625 nm whose crossing point matched lambda(max) in the UV region of MD. This result indicated that the PBLG chains and MDs were associated together to form spherical nanoparticles by hydrophobic interaction and the chiral PBLG core in the self-assembled copolymeric nanoparticles induced CD of J-aggregated MD. The helix sense of induced circular dichroism (ICD) of MD in the copolymeric nanoparticles was affected by the helix sense of PBLG in the copolymeric nanoparticles. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.