抄録
2-Methacryloyloxyethyl phosphorylcholine (MPC), which is known to exhibit excellent blood compatibility, was copolymerized with n-butyl methacrylate (BMA). The poly(MPC-co-BMA) copolymer (PMB) obtained was dissolved in aqueous media and aggregated into PMB polymer colloids. PMB50 and PMB30 (containing 50 and 30 mol% of MPC units in the feed, respectively) were evaluated. Aggregation of MPC polymer colloids was studied by dynamic light scattering, showing a diameter of 15–30 nm, where it was found that the diameter was dependent on the MPC-BMA monomer composition. 8-Anilino-1-naphthalenesulfonic acid sodium salt (ANS), as a fluorescence probe, was included into the hydrophobic domains formed through hydrophobic interactions between BMA units in the PMB colloid. The maximum fluorescence wavelength of ANS was in good agreement with a change in concentration of PMB, as reported in some previous studies. Pyrene as a fluorescence probe was incorporated in the hydrophobic domain as well, and the maximum excitation wavelength of pyrene varied with the concentration of PMB. By using the fluorescence intensity ratio of at a wavelength of λex = 334 and 338 (I334/I338), the critical association concentration (CAC) of the PMB polymer was determined to be 5 × 10-3 g/L for PMB30 and 1 × 10-2 g/L for PMB50. The partition equilibrium constant (Kv) was calculated, which was larger for PMB30 than for PMB50. Thus, hydrophobic molecules could easily dissolve into the hydrophobic domains, which could be regulated by the percentage of BMA units in the PMB polymer. In conclusion, the PMB polymer could be used as a bio-based material in drug delivery systems.
