A polysaccharide from the traditional Chinese medicinal herb, Bletilla striata (Thunb.) Reichb. f., was isolated, purified and characterized. It induced the proliferation of human umbilical vascular endothelial cells and the expression of vascular endothelial growth factor up to 156% and 147% of control after 72 h, respectively.

Cartilage defects as a result of disease or injury have a very limited ability to heal spontaneously. Recently, tissue engineering and local therapeutic gene delivery systems have been paid much attention in the cartilage natural healing process. Gene-activated matrix (GAM) blends these two strategies, serving as local bioreactor with therapeutic agents expression and also providing a structural template to fill the lesion defects for cell adhesion, proliferation and synthesis of extracellular matrix (ECM). In the current study, we used chitosangelatin complex as biomaterials to fabricate three-dimensional scaffolds and plasmid DNA were entrapped in the scaffolds encoding transforming growth factor-β1 (TGF-β1), which has been proposed as a promoter of cartilage regeneration for its effect on the synthesis of matrix molecules and cell proliferation. The plasmid DNA incorporated in the scaffolds showed a burst release in the first week and a sustained release for the other 2 weeks. The gene transfectd into chondrocytes expresses TGF-β1 protein stably in 3 weeks. The histological and immunohistochemical results confirmed that the primary chondrocytes cultured into the chitosan-gelatin scaffold maintained round and owned characters of high secretion of specific ECM. From this study, it can be concluded that this gene-activated chitosan-gelatins matrix has a potential in the application of cartilage defects regeneration.

To study the electrostatic interaction between two ionic polymer grafted surfaces in aqueous media, an atomic force microscopic tip surface was modified by graft polymerization of a cationic monomer, dimethylaminoethyl methacrylate (DMAEMA), after being coated with a thin layer of cyanoacrylate polymer. A poly(ethylene terephthalate) (PET) film which was the countersurface of the modified tip for the measurement of atomic force microscopy was also modified by surface graft polymerization of DMAEMA and an anionic monomer, acrylic acid (AAc) . An appreciable adhesive force was observed in water between the DMAEMA-grafted tip and the AAc grafted PET surface, while a repulsive interaction was noticed between the DMAEMA-grafted tip and the DMAEMA-grafted PET film. Addition of KCl to the medium for the atomic force measurement exhibited a remarkable reduction in the adhesive interaction. These interactions were attributed to the Coulombic force between the grafted ionic polymer chains.

Modification of argon plasma-pretreated single-crystal silicon wafer surface via UV-induced graft polymerization with various functional monomers, such as acrylamide (AAm), N,N- diamethylaminoethyl methacrylate (DMAEMA), and 2,2,2-trifluoroethyl acrylate (TFEA), was achieved. The modified Si(100) surfaces were characterized by X-ray photoelectron spectroscopy (XPS), imaging XPS, atomic force microscopy (AFM), and water contact angle measurements. The graft polymerization was affected by plasma pretreatment time and UV irradiation time. XPS results suggest that mild and brief plasma treatment is sufficient to cause surface oxidation and to generate sufficient peroxides and hydroxyl peroxides for the subsequent UV-induced graft polymerization in the presence of a vinyl monomer. Prolonged plasma treatment and the accompanying overoxidation of the silicon surface have an adverse effect on the graft polymerization. For all the cases investigated, the XPS results revealed that the grafted polymers form a thin layer with a thickness of 5 nm or less on the silicon surface. The AAm and TFEA graft-polymerized surfaces were uniform in morphology. However the DMAEMA graft-polymerized surface exhibited structural domains. Contact angle measurements further indicated that the silicon surface could be selectively made hydrophilic or hydrophobic through the proper choice of monomers used for graft polymerization.

Copper–poly(tetrafluoroethylene) (PTFE) and gold–PTFE laminates were prepared by surface graft copolymerization of glycidyl methacrylate (GMA) on argon plasma-pretreated PTFE films at an elevated temperature with simultaneous lamination to copper foils or gold substrates. The plasma pretreatment introduces peroxides, which are thermally degraded into radicals to initiate the graft copolymerization of GMA on the PTFE surface. Before lamination, the gold surface was pretreated with alkanethiols to form self-assembled monolayers and then subjected to an Ar plasma treatment. The modified surfaces and interfaces were characterized by x-ray photoelectron spectroscopy and the adhesion strength was assessed by the T-peel test method. By this technique, the Cu–PTFE or Au–PTFE laminates exhibit significantly improved adhesion strengths and the joints are delaminated by cohesive failure inside the bulk of the PTFE film.