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Collagen, the most abundant protein in mammals, is widely used for making biomaterials. Usually, organic solvents, such as 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), or acids (H 3 PO 4 , HAc ) have been used to disperse collagen to make collagen-based biomaterials. However, the native structure of collagen has been often seriously damaged and the concentration of collagen in solutions was constantly relatively low, which greatly limited its application. In this research, we have firstly made a detailed study of the effect of H + and HAc on collagen dispersing in terms of Zeta potential, particle size and Circular Dichroism (CD), after that a benign sodium acetate/acetic acid buffer solution is proposed to disperse collagen. The results showed that the collagen solution from NaAc/HAc buffer solution at pH=3.0 had the suitability of both high concentration (100mg/mL) and perfect native structure preservation (up to 94%). We demonstrated that it was the constant concentration of free H + in the NaAc/HAc buffer solution whose pH was fixed at 3.0 that can maintain the amount of surface charges on the collagen colloidal particles unchanged, which makes collagen dispersed well even in high dose. As an application, the collagen solution from NaAc/HAc solution at pH 3.0 was successfully electrospun into nanofibers, and the obtained collagen nanofibers still can keep as much as 57% of its native structure. This study indicated that the novel buffer solution of NaAc/HAc at pH 3.0 would be commonly used in the processing of collagen for a variety of biomaterials based on collagen solution, which had great potential for use in tissue engineering.

An anodic sulfurized treatment of Gaks has been developed to passivate its surfaces preventing oxidation. The photoemission core level spectra show that the surface Ga and As atoms are bonded to S atoms to form a thick sulfurized layer. No oxygen uptakes on the sulfurized GaAs surface as illustrated by the high resolution electron energy loss spectroscopy. The results of photoluminescence spectra verify that the passivated surface has low surface recombination velocity and can protect the photoassisted oxidation under laser illumination.

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Six novel coordination polymers, {[M2(L1)2(μ2-L1)2(4,4′-bipy)2]·CH3OH} n (HL1 = 3-(4-carboxylphenylamino)-1-ferrocenyl-2-butylen-1-one, 4,4′-bipy = 4,4′-bipyridine) (M = Zn (1) or Cd (2)), {[Cd2(η2-L2)2(μ2-η2-L2)2(4,4′-bipy)2]·CH3OH} n (HL2 = N-phenylanthranilic acid) (3), {[Cd2(μ-L3)(μ2-L3)(η2-L3)(4,4′-bipy)2(H2O)2]·NO3} n (HL3 = cinnamic acid) (4), {[Cd2(μ2-L4)4(4,4′-bipy)2]·2H2O} n (HL4 = hippuric acid) (5), and {[Cd2(μ2-η2-L5-η2)2(SO4)(4,4′-bipy)2(H2O)2]·5H2O} n (HL5 = 1-(carboxymethyl)-1,3-benzimidazol-3-ium-3-acetate) (6), have been synthesized and structurally characterized by single-crystal X-ray diffraction method. Polymers 1−4 exhibit one-dimensional (1-D) ladder-like structures, in which carboxylate ligands bridge two metal ions forming dinuclear cores, and 4,4′-bipy ligands link these cores. In polymers 5 and 6, the carboxylate-linked chains [Cd2(μ2-L4)4] n or mixed carboxylate and SO4 2− linked [Cd2(μ2-η2-L5-η2)2(SO4)] n chains are bridged by 4,4′-bipy ligands to form two-dimensional (2-D) sheet structures. In addition, the solution-state differential pulse voltammetries of polymers 1 and 2 were determined, and the photoluminescence properties of polymers 3−6 were investigated. The thermal properties of polymers 1−6 were determined as well.