Porphyrin containing light-responsive capsules for controlled drug release

Porphyrin containing capsules with light-response were fabricated via Layer-by-Layer (LbL) assembly of two biocompatible polymers, chitosan (CHI) and 5-(4-aminophenyl)-10,15,20-triphenyl-porphyrin (APP) graft polyaspartic acid (PASP-g-APP), on CaCO3 particles. FITC labeled dextran (FITC-Dex) was encapsulated in the core as a model drug. With CaCO3 particles removal by EDTA, hollow capsules loaded with FITC-Dex were obtained. The capsules could degrade and release FITC-Dex with light illumination due to the reactive oxygen species (ROS) produced by porphyrin. Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were used to characterize the capsules. The degradation behavior of the capsules was studied with CLSM and TEM.