Fuxin Liang

Rational Design and Synthesis of Janus Composites

Janus composites with two different components divided on the same object have gained growing interest in many fields, such as solid emulsion stabilizers, sensors, optical probes and self-propellers. Over the past twenty years, various synthesis methods have been developed including Pickering emulsion interfacial modification, block copolymer self-assembly, microfluidics, electro co-jetting, and swelling emulsion polymerization. Anisotropic shape and asymmetric spatial distribution of compositions and functionalities determine their unique performances. Rational design and large scale synthesis of functional Janus materials are crucial for the systematical characterization of performance and exploitation of practical applications.

Polymer nanotubes toward gelating organic chemicals

Crosslinked polymer nanotubes are large scale synthesized. The method is based on fast cationic polymerization using immiscible initiator nanodroplets. Nanoporous network processed from the nanotubes is superhydrophobic, which can absorb all the tested organic chemicals forming robust gels. The nanotubes are promising in the collection of spilled organic chemicals, detoxification and water treatment.

Janus Nanodisc of Diblock Copolymers

Janus nanodiscs of diblock copolymers are prepared by stepwise disassembly of PS-b-P4VP disc-stacked particles. The Janus nanodiscs are uniform in thickness and regular in contour. By preferential growth of functional materials at the positively charged P4VP side, the composition, microstructure, and performance of the Janus nanodiscs are tunable.

Multimodal porous CNT@TiO2 nanocables with superior performance in lithium-ion batteries

Multimodal porous CNT@TiO2 core–sheath coaxial nanocables have been constructed by a sol–gel method and post-calcination in the presence of polymer nanotubes acting as a template and carbon source. The composite exhibits excellent electrochemical properties, attaining a high discharge capacity of 231 mA h g−1 at 1000 mA g−1 for up to 110 cycles.

PEG-urokinase nanogels with enhanced stability and controllable bioactivity

Protein nanogels were synthesized via a one-step reaction procedure by crosslinking urokinase with benzaldehyde bifunctionalized poly(ethylene glycol). The crosslinked architecture significantly enhances the stability of urokinase against enzyme degradation in comparison with the core–shell structural PEGylated proteins. Meanwhile, bioactivity of the urokinase incorporated in the nanogels can be adjusted by varying the chain length of the corsslinking polymer. With a shorter crosslinker the bioactivity of the uPA nanogels is seriously restricted under physiological conditions. However, the restricted bioactivity can be completely launched by either enlarging the mesh size of the nanogel by using longer crosslinkers, or treating the nanogels in endosomal conditions to dissociate the nanogel structure due to the reversible conjugation chemistry.

pH-Responsive polymeric Janus containers for controlled drug delivery

In this study, we develop a novel approach to fabricate pH-responsive polymeric Janus hollow spheres (JHSs) with bi-layered structures by two-step polymerization with silica particles as templates. The inner layer is the biodegradable poly(e-caprolactone) (PCL) brush and the outer layer is cross-linked pH-responsive poly(diethylaminoethylmethacrylate) (PDEAEMA). So, these as-synthesized JHSs can selectively load oil-soluble materials into the cavities and controllably release them by changing the pH. Doxorubicin (DOX) is selected as a model drug which is loaded into the cavity of the JHSs and showed faster release at acidic pH than at physiological pH. It was revealed that the intracellular uptake of JHSs at the pH of tumorous tissues was significantly larger than that under the same conditions at the pH of the normal physiological environment.

Synthesis and characterization of biodegradable microcapsules for the controlled delivery of calcium hydroxide

This study aimed to synthesize and characterize biodegradable microcapsules based on poly(lactic acid) (PLA) and ethylcellulose (EC) for a controlled delivery of calcium hydroxide. Phase separation technique was adopted to synthesize calcium hydroxide-loaded PLA/EC microcapsules. Four PLA/EC blends (4/1, 1/1, 1/4, pure EC) were used as shell materials and the input ratio of calcium hydroxide to shell polymer was 4:1 for all microcapsules. The morphology and composition were studied using SEM-EDS and TEM. Particle size distribution, glass-transition temperature, drug loading, and encapsulation efficiency were characterized. In vitro release of the microcapsules was evaluated using a pH microelectrode and an auto-biochemistry analyzer. SEM images of microcapsules showed uniform spherical structures with smooth surfaces. Core-shell, hetero-structures were confirmed using TEM. The presence of calcium in the microcapsules was verified with EDS. Pure calcium hydroxide was 160 nm in diameter and the particle size of the microcapsules ranged between 500 nm and 4 μm. With an increase of PLA in PLA/EC blend, the size of microcapsules increased accordingly. Encapsulation efficiency of these microcapsules was higher than 57% and drug loading was higher than 80%, which were not significantly different among four microcapsules. Pure calcium hydroxide powder was used as a control and 90% was released within 48 h, while release of calcium hydroxide from microcapsules took between 168 and 456 h, depending on the PLA/EC ratio. Compared with calcium hydroxide powder, the calcium hydroxide-loaded microcapsules showed a sustained and prolonged release, which could be controlled via the regulation of the PLA/EC ratio.

Injectable tissue adhesive composite hydrogel with fibroblasts for treating skin defects

In this work, an injectable composite hydrogel was synthesized via a unique way of crosslinking glycol chitosan (GC) with silica nano-particles (SiNP) through non-chemical interactions, and was then applied as a kind of wound dressing. Gelation was achieved through the incorporation of SiNPs with the GC segments in aqueous solution, therefore strictly confining the movement of the solubilized polymer chains. Rheology tests showed that the sol-gel transition and the moduli of the hydrogel were influenced by the composition of the two components, the size of the nano-particles and the conformation of the polymers. Using such a strategy, tissue adhesion properties of GC were well-preserved in the GC/SiNP hydrogel and therefore it gains gluey properties toward biological tissues as demonstrated through the adhesion of two pieces of mouse skin, obtaining a lap-shear stretching force of ca. 90 kPa. This characteristic, together with the injectability, allowed the hydrogel to be administrated directly on the wound site and to fill the wound area. Meanwhile, the hydrogel also works as a carrier of protein and cells. The in situ encapsulation of fibroblasts enabled the promising properties of the GC/SiNP hydrogel to be used for treating full-thickness skin defects in a mouse model, resulting in the favorable growth of hair follicles and microvessels, hence reducing the risk of scar formation.

Fibril-shaped aggregates of doxorubicin with poly-L-lysine and its derivative

Complex formation between polymers and organic molecules is an interesting topic in polymer physics. Compared to the influence of small molecules on polymer assembly, there are fewer examples demonstrating the effect of polymers on the supramolecular structures formed by organic molecules. In this paper, we first prove that doxorubicin (DOX), a common anti-tumour drug, assembles into fibril-like aggregates in phosphate buffer (pH 7.4) and then show that the assembly of DOX was influenced by the complexation with an amphiphilic poly (amino acid) derivative, i.e. cholate-grafted poly-L-lysine (PLL-CA). With PLL-CA, the DOX fibrils converted to helix structured nano-spindles, whilst the presence of PLL led to minor change on the morphology of PLL/DOX complex compared to the DOX aggregates, which is attributed to the amplitude of intermolecular interactions. As a DNA intercalating agent, the aggregation of DOX on its biofunctionality was also investigated, showing that the formation of fibril assemblies was unfavourable for the cellular internalization of DOX and caused lower cytotoxicity to DOX resistance MCF-7 cells, whereas the polymer/DOX complexes gained an improved cell uptake on the MCF-7/ADR cell line due to an enhanced electrostatic interaction between the complexes and the cell membrane.

The Biological Performance of Calcium Hydroxide–loaded Microcapsules

INTRODUCTION Calcium hydroxide (Ca[OH]2) microcapsules were synthesized for use in controlled release. The aim of this study was to evaluate the cytotoxicity, antibacterial properties, and influence on gene expression of bone-related markers of 2 different formulas of Ca(OH)2 microcapsules. METHODS Two formulas of Ca(OH)2 microcapsules (A and B) were evaluated, and pure Ca(OH)2 powder was used as a positive control. The shell material of formula A was pure EC, and the PLA/EC blend of 1:1 was used as the shell material for formula B. The MG63 cells/Cell Counting Kit-8 (Dojindo, Kumamoto, Japan) were used to evaluate the cytotoxicity, and the colony-forming units of Enterococcus faecalis were monitored for the antibacterial effect. The relative messenger RNA expression of collagen I and osteocalcin was determined by real-time polymerase chain reaction. RESULTS Both formulas of the Ca(OH)2 microcapsules showed no cytotoxicity in MG63 cells; however, the Ca(OH)2 positive control did exhibit cytotoxicity. The antibacterial effect of the 2 microcapsule formulas lasted longer than the positive control, and formula A lasted longer than formula B. For both Ca(OH)2 microcapsule formulas, the relative messenger RNA expression of collagen I and osteocalcin was prolonged and up-regulated. The time effects of the influence on messenger RNA expression of collagen I and osteocalcin were different between the 2 microcapsule formulas. CONCLUSIONS Ca(OH)2 microcapsules had prolonged antibacterial activity and prolonged the up-regulation of bone-related markers with reduced cytotoxicity.