Core/shell microspheres via coaxial electrohydrodynamic atomization for sequential and parallel release of drugs.

Herein, it is demonstrated that coaxial electrohydrodynamic atomization can be used for the fabrication of microspheres with distinct core/shell structure. This allows the encapsulation of two different types of drugs in different compartments in one single step. In Group A, we prepared microspheres in which the core and the shell contain hydrophobic and hydrophilic drugs, respectively. In contrast, in Group B, the opposite is prepared. While the former can be achieved by using amphiphilic polymers in aqueous environment, the latter is difficult to be prepared. The release patterns of the two groups are significantly different. The release of drugs from Group A microspheres is rather sequential, whereas group B microspheres release drugs in a parallel (co-release) manner. Nevertheless, in both groups, we found that the release of drugs can be easily tailored by altering outer/inner flow ratios. These findings present the advantages and possible application of this multi-drug release system in chemotherapy. Moreover, cell culture experiments have been performed to testify the performances of different microspheres in cytotoxicity and cellular apoptosis in vitro.