Controlled delivery of paracetamol and protein at different stages from core–shell biodegradable microspheres

The core–shell biodegradable microspheres loading human serum albumin (HSA) and paracetamol were fabricated with a hydrophilic alginic acid (ALG) shell and a hydrophobic poly(lactic-co-glycolic acid) (PLGA) core. The two model drugs, HSA and paracetamol, were entrapped in the shell and core, respectively. Theses microspheres were characterized in terms of morphology, mean size and size distribution, drug loading efficiency, in vitro degradation and drugs release. The optical microscopy (OM) and transmission electron microscope (TEM) photos revealed directly that the microspheres possessed core–shell structure. The degradation results showed that there were quick drop phases in weight of polymer matrix and in pH of degradation medium after 2 weeks. In vitro release profiles showed that within the initial 20 h, only HSA was almost released from the shell layers, whereas only another drug, paracetamol, was almost released from the cores in the following period.