The molecular mechanism of apatite formation on bioactive glass surface is studied using the techniques of XRD, EDX, SEM, FT-IR, and solid-state 31 P NMR. Using the sol-gel method a bioactive glass system containing glass beads of 2 to 3 microns in size is prepared with the composition containing 30% CaO -70% SiO 2 . Our experimental data support the apatite formation mechanism proposed by Hench concerning the precipitation and crystallization of calcium phosphate. The phosphate ions initially deposited on the glass surface are largely in amorphous phase and have substantial amount of water molecules in the surrounding. As the soaking time in simulated body fluid increases, some of the water molecules diffuse out of the phosphate lattice, leading to the formation of a crystalline phase. Our data show that the structure of the crystalline phase is different from type B carbonate apatite but similar to hydroxyapatite.

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A multi-functional mesoporous silica nanoparticle (MSN)-based boron neutron capture therapy (BNCT) agent, designated as T-Gal-B-Cy3@MSN, was synthesized with hydrophobic mesopores for incorporating a large amount of o-carborane (almost 60% (w/w) boron atoms per MSN), and the amines on the external surface were conjugated with trivalent galactosyl ligands and fluorescent dyes for cell targeting and imaging, respectively. The polar and hydrophilic galactosyl ligands enhance the water dispersibility of the BNCT agent and inhibit the possible leakage of o-carborane loaded in the MSN. Confocal microscopic images showed that T-Gal-B-Cy3@MSNs were endocytosed by cells and were then released from lysosomes into the cytoplasm of cells. Moreover, in comparison with the commonly used clinical BNCT agent, sodium borocaptate (BSH), T-Gal-B-Cy3@MSN provides a higher delivery efficiency (over 40-50 fold) of boron atoms and a better effect of BNCT in neutron irradiation experiments. MTT assays show a very low cytotoxicity for T-Gal-B-Cy3@MSN over a 2 h incubation time. The results are promising for the design of multifunctional MSNs as potential BNCT agents for clinical use.

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Development of topical bioactive formulations capable of overcoming the low bioavailability of conventional eye drops is critically important for efficient management of ocular chemical burns. Herein, a nanomedicine strategy is presented to harness the surface roughness‐controlled ceria nanocages (SRCNs) and poly(l‐histidine) surface coatings for triggering multiple bioactive roles of intrinsically therapeutic nanocarriers and promoting transport across corneal epithelial barriers as well as achieving on‐demand release of dual drugs [acetylcholine chloride (ACh) and SB431542] at the lesion site. Specifically, the high surface roughness helps improve cellular uptake and therapeutic activity of SRCNs while exerting a negligible impact on good ocular biocompatibility of the nanomaterials. Moreover, the high poly(l‐histidine) coating amount can endow the SRCNs with an ≈24‐fold enhancement in corneal penetration and an effective smart release of ACh and SB431542 in response to endogenous pH changes caused by tissue injury/inflammation. In a rat model of alkali burn, topical single‐dose nanoformulation can efficaciously reduce corneal wound areas (19‐fold improvement as compared to a marketed eye drops), attenuate ≈93% abnormal blood vessels, and restore corneal transparency to almost normal at 4 days post‐administration, suggesting great promise for designing multifunctional metallic nanotherapeutics for ocular pharmacology and tissue regenerative medicine.

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