Browsing by Author "Liao, Chen-Fu"

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Controlled Rupture of Magnetic Polyelectrolyte Microcapsules for Drug Delivery
(2008-10-21)
Hu, Shang-Hsiu
;
Tsai, Chia-Hui
;
Liao, Chen-Fu
;
Liu, Dean-Mo
;
Chen, San-Yuan
In this study, a magnetic-sensitive microcapsule was prepared using Fe3O4/poly(allylamine) (Fe3O4/PAH) polyelectrolyte to construct the shell. Structural integrity, microstructural evolution, and corresponding release behaviors of fluorescence dyes and doxorubicin were systematically investigated. Experimental observations showed that the presence of the magnetic nanoparticles in the shell structure allowed the shell structure to evolve from nanocavity development to final rupture of the shell under a given magnetic stimulus of different time durations. Such a microstructural evolution of the magnetic sensitive shell structure explained a corresponding variation of the drug release profile, from relatively slow release to burst-like behavior at different stages of stimulus. It has proposed that the presence of magnetic nanoparticles produced heat, due to magnetic energy dissipation (as Brown and Neel relaxations), and mechanical vibration and motion that induced stress development in the thin shell. Both mechanisms significantly accelerated the relaxation of the shell structure, causing such a microstructural evolution. With such a controllable microstructural evolution of the magnetic-sensitive shell structure, active substances can be well-regulated in a manageable manner with a designable profile according to the time duration under magnetic field. A cell culture study also indicated that the magnetic-sensitive microcapsules allowed a rapid uptake by the A549 cell line, a cancerous cell line, suggesting that the magnetic-sensitive microcapsule with controllable rupturing behavior of the shell offers a potential and effective drug carrier for anticancer applications.
Surfactant-Free, Self-Assembled PVA-Iron Oxide/Silica Core-Shell Nanocarriers for Highly Sensitive, Magnetically Controlled Drug Release and Ultrahigh Cancer Cell Uptake Efficiency
(2008-10-09)
Hu, Shang-Hsiu
;
Liu, Dean-Mo
;
Tung, Wei-Lin
;
Liao, Chen-Fu
;
Chen, San-Yuan
Surfactant-free, self-assembled iron oxide/silica core-shell (SAIO@SiO2) nanocarriers were synthesized as bifunctional magnetic vectors that can be triggered for the controlled release of therapeutic agents by an external magnetic field. In addition, drug release profiles can be well-regulated through an ultrathin layer of silica shell. The hydrophobic drug molecules were encapsulated within the iron oxide-PVA core and then further covered with a thin-layer silica shell to regulate the release pattern. Remote control of drug release from the SAIO@SiO2 nanocarriers was achieved successfully using an external magnetic field where the core phase being structurally disintegrated to a certain extent while subjected to magnetic stimulus, resulting in a burst release of the encapsulated drug. However, a relatively slow and linear release restored immediately, directly after removal of the stimulus. The nanostructural evolution of the nanocarriers upon the stimulus was examined and the mechanism for controlled drug release is proposed for such a core-shell nanocarrier. Surprisingly, the surfactant-free SAIO@SiO2 nanocarriers demonstrated a relatively high uptake efficiency from the HeLa cell line. Together with a well-regulated controlled release design, the nanocarriers may provide great advantages as an effective cell-based drug delivery nanosystem for biomedical applications.