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Hybrid Mesoporous Nanoparticles for pH-Actuated Controlled Release

Centro de Química Estrutural and CQFM-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
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Nanomaterials 2019, 9(3), 483; https://doi.org/10.3390/nano9030483
Received: 11 March 2019 / Revised: 18 March 2019 / Accepted: 21 March 2019 / Published: 26 March 2019
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Abstract

Among a variety of inorganic-based nanomaterials, mesoporous silica nanoparticles (MSNs) have several attractive features for application as a delivery system, due to their high surface areas, large pore volumes, uniform and tunable pore sizes, high mechanical stability, and a great diversity of surface functionalization options. We developed novel hybrid MSNs composed of a mesoporous silica nanostructure core and a pH-responsive polymer shell. The polymer shell was prepared by RAFT polymerization of 2-(diisopropylamino)ethyl methacrylate (pKa ~6.5), using a hybrid grafting approach. The hybrid nanoparticles have diameters of ca. 100 nm at pH < 6.5 and ca. 60 nm at pH > 6.5. An excellent control of cargo release is achieved by the combined effect of electrostatic interaction of the cargo with the charged silica and the extended cationic polymer chains at low pH, and the reduction of electrostatic attraction with a simultaneous collapse of the polymer chains to a globular conformation at higher pH. The system presents a very low (almost null) release rate at acidic pH values and a large release rate at basic pH, resulting from the squeezing-out effect of the coil-to-globule transition in the polymer shell. View Full-Text
Keywords: smart hybrid nanoparticles; mesoporous silica nanoparticles; RAFT polymerization; pH-responsive; polymer shell; controlled release smart hybrid nanoparticles; mesoporous silica nanoparticles; RAFT polymerization; pH-responsive; polymer shell; controlled release
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Gonçalves, J.L.M.; Crucho, C.I.C.; Alves, S.P.C.; Baleizão, C.; Farinha, J.P.S. Hybrid Mesoporous Nanoparticles for pH-Actuated Controlled Release. Nanomaterials 2019, 9, 483.

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