Preparation and evaluation of SN-38-loaded MMP-2-responsive polymer micelles

7-Ethyl-10-hydroxycamptothecin (SN-38)-loaded polyethylene glycol-GPLGVRG-poly β-benzyl- l -aspartic acid (PEG-GPLGVRG-PBLA) self-assemblies were successfully prepared using a classical nanoprecipitation method to give an enzyme-responsive nano-drug delivery system. The PEG-GPLGVRG-PBLA/SN-38 self-assemblies were characterized by transmission electron microscopy , dynamic light scattering , and high-performance liquid chromatography. The encapsulation efficiency was 91.7 ± 1.21% and the drug loading was 16.6 ± 0.93%. The 12 h in vitro release of SN-38 from PEG-GPLGVRG-PBLA/SN-38 treated with MMP-2 was 73.2 ± 2.05%, which was significantly higher than that for the group without MMP-2, demonstrating the enzyme-responsiveness of the nano-drug delivery system. In addition, the cellular uptake and tumor accumulation of PEG-GPLGVRG-PBLA were better than those of PEG-PBLA, and the blank PEG-GPLGVRG-PBLA showed high biocompatibility . These findings indicate that the enzyme-responsive nano SN-38 delivery system could provide new opportunities in tumor therapy.