Yingchun Su

Polydopamine-coated liposomes as pH-sensitive anticancer drug carriers.

Abstract Stimuli-responsive drug carriers are considered to play important roles in chemotherapy. We fabricated pH-sensitive polydopamine-protected liposomes (liposome@PDA) drug delivery systems, which were characterised with microscope, scanning electron microscope (SEM), UV-vis spectrometer and Fourier transform infrared (FTIR) technieques. The typical chemotherapeutic agent, 5-fluorouracil (5-FU), was loaded into liposome@PDA capsules. The maximum release percentages of 5-FU are 3.2%, 29.5%, 52.7%, 76.7% in the solution with pH 7.42, 6.87, 4.11 and 3.16, respectively. The in vitro cell cytotoxity experiments were carried out using 5-FU-loaded capsules at pH 6.87 solution, which simulate the true pH around cancerous cells. At 1.5 μM concentration, the free 5-FU, 5-FU-loaded liposome capsules and 5-FU-loaded capsules showed the cell viability of 50.56%, 22.66% and 21.63%, respectively. It confirms that drug-loaded capsules performed better than free drug. The results demonstrate the great potential of liposome@PDA capsules as carriers in biomedical applications.

Palladium Nanotubes Formed by Lipid Tubule Templating and Their Application in Ethanol Electrocatalysis

Palladium nanotubes were fabricated by using lipid tubules as templates for the first time in a controlled manner. The positively charged lipid 1,2-dioleoyl-3-trimethylammoniumpropane (DOTAP) was doped into lipid tubules to adsorb PdCl4 (2-) on the tubule surfaces for further reduction. The lipid tubule formation was optimized by studying the growing dynamics and ethanol/water ratio. The DOTAP-doped tubules showed pH stability from 0 to 14, which makes them ideal templates for metal plating. The Pd nanotubes are open-ended with a tunable wall thickness. They exhibited good electrocatalytic performance in ethanol. Their electrochemically active surface areas were 6.5, 10.6, and 83.2 m(2)  g(-1) for Pd nanotubes with 77, 101, and 150 nm wall thickness, respectively. These Pd nanotubes have great potential in fuel cells. The method demonstrated also opens up a way to synthesize hollow metal nanotubes.

High impedance droplet-solid interface lipid bilayer membranes.

A droplet-solid interface lipid bilayer membrane (DSLM) with high impedance was developed through controlling the contact area between an aqueous droplet and electrode. The electrode size can be easily controlled from millimeter to micrometer level. The droplet-solid interface lipid bilayer membranes were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and fluorescence microscopy. The fluorescence recovery after photobleaching (FRAP) was applied to determine the diffusion coefficient of egg PC DSLM to be 2.58 μm(2) s(-1). The DSLM resistance can reach up to 26.3 GΩ, which was then used to study the ion channel behavior of melittin. The resistivity of the bilayer membrane decreased linearly with the increase of melittin concentration in the membrane. The high impedance and fluidity of DSLM makes it an ideal model cell membrane system for ion channel study and high-throughput drug screening.

Inorganic microcapsules mineralized at the interface of water droplets in ethanol solution and their application as drug carriers

This paper reported a crystallization – dissolution – interface mineralization (CDIM) method on synthesizing calcium carbonate (CaC) and calcium phosphate (CaP) inorganic microcapsules with good biocompatibility and good pH sensitivity. The method is based on mineralization at the ethanol/water interface. The microcapsules were formed in a few seconds and did not need post treatment for removing the templates. The diameters of the microcapsules can be controlled by the size of the crystal clusters regulated by stirring time. Carboxyfluorescein (CF) molecules as model drugs were encapsulated inside the capsules after coating with FeIII–polyphenol tannic acid (TA) films. The pH sensitive carboxyfluorescein molecule releasing behavior was investigated. The lower pH caused faster and thorough release of CF. The CDIM method can be applied for fabricating other inorganic microcapsules, which holds great potential for drug delivery.

MoS2@HKUST‐1 Flower‐Like Nanohybrids for Efficient Hydrogen Evolution Reactions

A novel MoS2 -based flower-like nanohybrid for hydrogen evolution was fabricated through coating the Cu-containing metal-organic framework (HKUST-1) onto MoS2 nanosheets. It is the first time that MoS2 @HKUST-1 nanohybrids have been reported for the enhanced electrochemical performance of HER. The morphologies and components of the MoS2 @HKUST-1 flower-like nanohybrids were characterized by scanning electron microscopy, X-ray diffraction analysis and Fourier transform infrared spectroscopy. Compared with pure MoS2 , the MoS2 @HKUST-1 hybrids exhibit enhanced performance on hydrogen evolution reaction with an onset potential of -99 mV, a smaller Tafel slope of 69 mV dec-1 , and a Faradaic efficiency of nearly 100 %. The MoS2 @HKUST-1 flower-like nanohybrids exhibit excellent stability in acidic media. This design opens new possibilities to effectively synthesize non-noble metal catalysts with high performance for the hydrogen evolution reaction (HER).

A green method to synthesize flowerlike Fe(OH)3 microspheres for enhanced adsorption performance toward organic and heavy metal pollutants

Dyestuffs and heavy metal ions in water are seriously harmful to the ecological environment and human health. Three-dimensional (3D) flowerlike Fe(OH)3 microspheres were synthesized through a green yet low-cost injection method, for the removal of organic dyes and heavy metal ions. The Fe(OH)3 microspheres were characterized by thermal gravimetric analysis (TGA), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) techniques. The adsorption kinetics of Congo Red (CR) on Fe(OH)3 microspheres obeyed the pseudo-second-order model. Cr6+ and Pb2+ adsorption behaviors on Fe(OH)3 microspheres followed the Langmuir isotherm model. The maximum adsorption capacities of the synthesized Fe(OH)3 were 308, 52.94, and 75.64mg/g for CR, Cr6+, and Pb2+ respectively. The enhanced adsorption performance originated from its surface properties and large specific surface area of 250m2/g. The microspheres also have excellent adsorption stability and recyclability. Another merit of the Fe(OH)3 material is that it also acts as a Fenton-like catalyst. These twin functionalities (both as adsorbent and Fenton-like catalyst) give the synthesized Fe(OH)3 microspheres great potential in the field of water treatment.

High-concentration organic dye removal using Fe2O3·3.9MoO3 nanowires as Fenton-like catalysts

In the past few years, nanomaterials have shown great potential for organic waste water treatment. Herein, we report the single-step ligand-free synthesis of Fe2O3·nMoO3 composites with different morphologies, including nanowires, bowknot-like microstructures, and urchin-like microstructures, through an oriented-attachment mechanism. It is the first time that Fe2O3·3.9MoO3 nanowires were synthesized successfully with tunable lengths from 5.1 μm to 37.4 μm as efficient and recyclable Fenton-like catalysts for Congo red. 97.8% degradation efficiency within 60 min and a kinetic constant of 9.0 × 10−3 L mg−1 min−1 according to the second order kinetic reaction equation were achieved. The degradation capacity for 250 mg L−1 Congo red is up to 231.4 mg g−1, which shows their excellent degradation ability at high dye concentrations. The Fe2O3·3.9MoO3 nanowires show great potential for organic pollutant removal.