Hollow DNA/PLL microcapsules with tunable degradation property as efficient dual drug delivery vehicles by α-chymotrypsin degradation

Hollow deoxyribonucleic acid (DNA)/poly-l-lysine (PLL) capsules were successfully fabricated through a layer-by-layer (LbL) self-assembly of DNA and PLL on porous CaCO3 microparticles, followed by removal of templates with ethylenediamine tetraacetic acid disodium salt (EDTA). The enzymatic degradation of the capsules in the presence of α-chymotrypsin was explored. The higher the enzyme concentration, the higher is the degradation rate of hollow capsules. In addition, glutaric dialdehyde (GA) cross-linking was found to be another way to manipulate degradation rate of hollow capsules. DNA/PLL capsules with a higher GA cross-linking density degraded at a lower rate. Dextran, as a model drug, was then encapsulated into DNA/PLL microcapsules via spontaneous deposition mechanism, and the loading process was observed by the confocal microscope using fluorescence labeled dextran. This capsule system showed a high loading capacity for Dextran. The resultant capsules were then used as dual carriers for DNA and dextran by enzymatic degradation, and they could effectively discharge drug payloads. This dual carrier system is expected to find applications in biomedical fields owing to their good biocompatibility and high transport efficiency of drug, and utilization of the cooperative effect of DNA and non-gene drug.