Tuning kinetics of controlled-release in disulfide-linked MSN-folate conjugates with different fabrication procedures

A drug delivery system based on disulfide-linked MSN-folate conjugates is fabricated via co-condensation and post-grafting methods. The premature leakage before DDSs reach the specific site is eliminated due to the covalent conjugation, which is desirable for drug delivery, especially for the delivery of those highly toxic anticancer drugs. Interestingly, the controlled release responsive to redox stimuli is tunable by using different fabrication procedure. The system fabricated with co-condensation exhibits first-order release while that with post-grafting exhibits zero-order release. The constant release rate is an especially interesting behavior that avoids peaks in the rate of drug delivery. The cumulative release data were used to fit in Korsmeyer-Peppas model to figure out the release mechanism. The exponent n = 0.22 for MF1 indicates Fick diffusion while n = 0.49 for MF2 indicates non-Fick or anomalous diffusion. (C) 2011 Elsevier B.V. All rights reserved.