Redox-responsive nanoreservoirs: The effect of different types of mesoporous silica on the controlled release of doxorubicin in solution and in vitro

• Controlled release nanoreservoirs based on SBA-15 and MCM-41 were constructed.
• The pores were capped by surface grafted host–guest pair-Fc@β-CD linked to AuNPs.
• Release of doxorubicin (DOX) from the reservoirs depended on [O2], pH and support.
• These systems were used to deliver DOX to B16F10 mouse melanoma cancer cells.
• Cell viability results suggest that both systems improved internalization of DOX.

Controlled release systems based on SBA-15 and MCM-41 have been obtained by grafting the surfaces of these mesoporous silica nanoparticles with the host–guest pair ferrocenyl group (–Fc)@β-cyclodextrin attached to Au nanoparticles (β-CDS-AuNPs). Investigation of doxorubicin (DOX) release from the FcSBA-15/β-CDS-AuNPs and FcMCM-41/β-CDS-AuNPs nanoreservoirs, triggered by oxidation of the –Fc group in weakly acidic medium, was monitored by fluorescence spectroscopy. The results have evidenced that DOX release depends not only on [O2] and pH, but most importantly, on the type of support. Indeed, the kinetics of DOX delivery from the SBA-15 based nanoreservoir at pH 6.5 and ambient [O2] was about 10 times slower than from the analogous reservoir based on MCM-41, however, no appreciable effect on the DOX release kinetics was observed upon changing the β-CDS-AuNPs cap of the latter nanoreservoir for β-CD (i.e., from FcMCM-41/β-CD). These systems were used to deliver DOX to B16F10 mouse melanoma cancer cells. Cell viability results determined by MTT assays have shown that DOX loaded-nanoreservoirs were more toxic to the B16F10 cells than both free DOX and empty nanoreservoirs, at [DOX] of 22 nmol L−1, thus suggesting that the nanoreservoirs have improved internalization of DOX in tumor cells.

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