4. CONCLUSIONS
In this study, a tumor-targeted and enzyme-induced drug-
delivery system was designed and constructed by immobilizing
cleavable rotaxanes onto MSNs. Instead of traditional host−
guest interaction between cyclodextrin and adamantine, a
multifunctional peptide azido-GFLGR7RGDS was used to act
as the enzyme-cleavable stopper for the cyclodextrin rotaxane
valve through click chemistry. DOX@MSN-GFLGR7RGDS/α-
CD has been proved to be capable of efficient uptake by tumor
cells via cell integrins receptor-mediated targeting, and is superb
for specifically delivering DOX into tumor cells via enzymatic
digestion of GFLG peptide. Moreover, free RGDS peptides