phase (2). This organized PLGA assembly is also expected A novel poly(L-glutamic acid)-functionalized amphiphile (2) to provide a site in which a guest molecule can be specificontaining spiropyran groups in the side chain was successfully cally trapped. Actually we have found that the monolayer prepared. Surface monolayers of 2 were affected by isomerization of 1 has the ability to capture a-amino acids enantioselecof the spiropyran group; i.e., 2sp, which is in the spiro form, gave tively in aqueous solution (3). As part of our research into an expanded monolayer comparable with that of the spiropyranthe conformational properties of polyelectrolyte chains free 1, while 2mc in the cyanine form gave a well-condensed monoembedded in molecular assemblies, we have newly prelayer similar to the 1 monolayer. CD measurements for these depared a photo-responsive PLGA amphiphile (2) conposited monolayers onto quartz plates showed that the helix containing spiropyran units in the side chains and revealed tent was higher for the 2sp monolayer than for the 2mc monolayer.
Upon isomerization from the cyanine to the spiro form, the 2mc the conformational behavior in a monolayer state on water monolayer had a tendency to expand gradually. When D-trypto-(see Scheme 1). Ciardelli et al. showed that a spiropyranphan was added into the subphase, such a monolayer expansion carrying PLGA in aqueous solution can undergo a large was completely suppressed due to electrostatic interactions berandom coil-a-helix conformational change upon expotween zwitterions, whereas no effect of the addition of L-tryptosure to sunlight and dark conditions, alternately (4). If phan on the monolayer was observed. This result suggests that such a PLGA can be aligned at the air/water interface, the assembled structure of a-helical poly(L-glutamic acid) would photo-induced conformational variations in the PLGA asprovide a suitable site for capturing a-amino acid enantioselecsembly would be dynamically investigated by means of tively.