To prepare natural nano-HA and a natural nano-hydroxypatite/chitosan (CH) composite and to study the biocompatibility of natural nano-hydroxypatite/chitosan composite. Natural hydroxyapatite (HA) was prepared from animal’s bone according to a calcining method, the natural nano-HA was prepared by using planetary ball milling, and the composite was prepared via in-situ precipitation. TEM and SEM were used to observe the size of natural nao-hydroxypatite and the microstructure of the composite. The biocompatibility of natural nano-HA/CH composite was evaluated by MTT test. The TEM micrography of the natural nano-HA showed that the size of the particles is below 100nm, and the composite reported in this study has layer-by-layer structure. The result of MTT-test showed the cytotoxicity level of the prepared composite was 0. The nano-HA/CH composite has good biocompatibility, and it can be potentially applied as internal fixation of bone fracture.

Using a biomedical sensor setup RIfS we have investigated the kinetic behavior of human albumin (Alb), human fibrinogen (Fib), and human immunoglobulin G (IgG) adsorbed onto surfaces of chitosan. Polystyrene (PS) was used as the control material in this study. The optical thickness of three kinds of proteins measured by RIfS was related to their molecular dimensions and potential orientations on a film surface. According to the operation principle of RIfS and the molecular dimensions of three kinds of proteins, the adsorbed layers of proteins onto the surface of chitosan and PS was calculated by using a newly introduced equation. The microstructure of the chitosan and polystyrene film and the surfaces with adsorbed proteins were imaged by atomic force microscopy (AFM). With AFM analyses the lateral distribution of the protein molecules on surfaces have been recognized. The results show that the number of adsorbed layers of the three proteins on the surface of chitosan are 0.635 for Alb, 0.158 for Fib and 0.0967 for IgG, and of polystyrene are: 0.577 for IgG, 0.399 for Fib, 0.336 for Alb. This study confirmed that RIfS is a useful tool for the analysis of plasma proteins adsorbed on a surface of biomaterials. Results show that at first on the surface of chitosan film much more Alb than Fib was adsorbed which demonstrated that chitosan has an antithrombus function. Secondly, on the surface of chitosan film more Alb and less Fib were adsorbed than on the surface of PS film, which demonstrated that chitosan has a better blood compatibility than polystyrene. Thirdly, the calculated layer number of the three proteins indicated that on both chitosan and PS substrates monolayer coatings form.

The aim of present work was to study the interaction between human plasma protein-albumin (Alb) and immunoglobulin G (IgG) and the surfaces of two kinds of diamond-like Carbon (DLC-A and DLC-B) and titanium (Ti) film. Fourier transform infrared spectroscopy (FTIR) was used to perform both quantity investigation and secondary structure analysis of above two proteins adsorbed on material surfaces. A modified Coomassie brilliant blue (CBB) protein assay was also used to study the amount of adsorbed proteins. The result of FTIR quantitative evaluation shows that the ratio of adsorbed Alb to IgG (RA/I) on three kinds of material surface has an order: DLC-A > DLC-B > Ti, which is coincide with the result from CBB protein assay. The result of secondary structure analysis shows that the conformation of Alb and IgG changes in a largest degree after adsorbed on Ti and a smallest degree on DLC-A surface. Both the results indicate that the anti-thrombogenicity of DLC-A seems to be the best and Ti is the worst.

The aim of this study was to compare the plasma protein adsorptive property of the natural hydroxyapatite (HA) and the synthesized HA to human albumin (Alb), fibrinogen (Fib) and immunoglobulin G (IgG). Different methods such as reflectometry interference spectroscopy (RIfS) measuring, Fourier transform infrared spectroscopy (FTIR) analysis and weighing assessment were used to measure the adsorbed amount of Alb, Fib and IgG on the natural HA and the synthesized HA. To compare the adsorptive property of protein adsorbed on these two kinds of materials, the ratio of Alb/Fib (RA/F) and the ratio of Alb/IgG (RA/I) were calculated. The results from all three methods showed that the values of RA/F and RA/I obtained with natural HA were smaller than those obtained with synthesized HA, that indicated that the natural HA adsorbed more human fibrinogen than human albumin and thas it would enhance blood coagulation and in favor of bone repairing.

This paper presents a fully integrated and low power CMOS amplifier for neural signal recording. It consists of a band-filtering preamp and a current-mode instrumentation amplifier. The design approach and the noise optimizing are briefly discussed. A 0.6