Xianming Dong

Controlled synthesis of SnO2@carbon core-shell nanochains as high-performance anodes for lithium-ion batteries

A new low-flow-rate inert atmosphere strategy has been demonstrated for the synthesis of perfect SnO2@carbon core-shell nanochains (SCNCs) by carbonization of an SnO2@carbonaceous polysaccharide (CPS) precursor at a relatively high temperature. This strategy results in the thorough carbonization of CPS whilst avoiding the carbothermal reduction of SnO2 at 700 °C. It has been investigated that a moderate carbon content contributes to the 1-D growth of SCNCs, and the thickness of the carbon shell can be easily manipulated by varying the hydrothermal treatment time in the precursor process. Such a unique nanochain architecture could afford a very high lithium storage capacity as well as resulting in a desirable cycling performance. SCNCs with about 8 nm carbon shell synthesized by optimized routes were demonstrated for optimal electrochemical performances. More than 760 mAh g¬1 of reversible discharge capacity was achieved at a current density of 300 mA g−1, and above 85% retention can be obtained after 100 charge-discharge cycles. TEM analysis of electrochemically-cycled electrodes indicates that the structural integrity of the SnO2@carbon core-shell nanostructure is retained during electrochemical cycling, contributing to the good cycleability demonstrated by the robust carbon shell.

Electrospray biodegradable microcapsules loaded with curcumin for drug delivery systems with high bioactivity

In the present work, polylactic acid (PLA) microcapsules as novel drug delivery systems were successfully fabricated by one-step processing using an electrospray technique. Curcumin (Cur) was chosen as model drug with satisfactory loading capacity (LC%) and entrapment efficiency (EE%) greater than 95%. By judiciously adjusting spinning solvents, flow rates, polymer and drug concentrations, the monodisperse and spherical structures of Cur/PLA microcapsules observed using scanning electron microscopy (SEM) and optical microscopy were successfully generated with diameter distribution ranging from 3.8 μm to 4.4 μm. The physical-chemical characterization including, FTIR, XRD, TG, and DTA, are explored and in vitro release profiles described by Ritger–Peppas models were also investigated, showing sustained release for 200 h after a burst release in the initial 12 h. The drug-loaded microcapsules showed excellent anti-bacterial activities towards Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by using both disk diffusion and minimal inhibitory concentration methods. The anti-oxidant performance was also evaluated by using DPPH assays. In vitro cell tests, including Cell Counting Kit-8, hemolysis experiments, and cell adhesion revealed that PLA-based microcapsules had significant biocompatibility and low cytotoxicity. The study showed that the PLA-based electrospray strategy combined with spherical microcapsules has the potential for a broad range of applications in medical fields, especially in drug delivery.

Close-packed mesoporous carbon polyhedrons derived from colloidal carbon microspheres for electrochemical energy storage applications

A new class of mesoporous carbon polyhedrons (MCPs) with a facet-to-facet close-packed model are presented for the first time as electrode materials for electrochemical capacitors (ECs). These MCPs are evolved directly from the colloidal carbon microspheres (CCMs) by a new silica-free approach, the top-down carbonate (Li2CO3) site-occupying strategy. The obtained polyhedral materials consist of a desirable mesoporous structure with mesopores with a mean size of about 30 nm. The unique structures of the large-size mesopores in a close-packed combination are considered to provide a more favourable pathway for electrolyte penetration and transportation, as well as good electronic conductivity for electrochemical energy storage applications. Accordingly, the resultant mesoporous materials show great promise for high performance EC applications, of which high energy and high power properties are desirable.

Facile preparation of biocompatible poly(l-lactic acid)-modified halloysite nanotubes/poly(ε-caprolactone) porous scaffolds by solvent evaporation of Pickering emulsion templates

Biocompatible porous scaffolds with tunable microstructures and drug delivery ability have aroused increasing attention in the application of the biomedical fields, especially in tissue engineering. In this study, we have facilely fabricated the poly(l-lactic acid)-modified halloysite nanotubes (m-HNTs)/poly(ε-caprolactone) (PCL) porous scaffolds by direct solvent evaporation of m-HNTs stabilized water in oil Pickering emulsion templates, which contain PCL in the oil phase. The obtained scaffolds have possessed the porous microstructures, which can be easily tailored by varying the preparation conditions of emulsion templates including m-HNTs concentrations and the volume ratios of water to oil. Furthermore, the antibacterial drug enrofloxacin (ENR) has been loaded into the scaffolds, and the in vitro release studies show the potential of m-HNTs/PCL porous scaffolds as drug carriers. And the antimicrobial test results have proved that the ENR-loaded porous scaffolds exhibit obvious and long-term antibacterial activity against Escherichia coli. In addition, mouse bone mesenchymal stem cells (mBMSCs) are cultured on the m-HNTs/PCL porous scaffolds, and the results of cell counting kit-8 assay and confocal laser scanning microscope observation show that the m-HNTs/PCL porous scaffolds are cytocompatible, because mBMSCs can attach, develop and proliferate well on the porous scaffolds. All the results indicate that the m-HNTs/PCL porous scaffolds hold great potential applications in tissue engineering as scaffolds and/or drug carriers.