Test circuits for the signal detection and the function electrical stimulation (FES) of neurons have been designed, implemented at first by using discrete devices and characterized off-body. The detecting circuit consisting of three-stage operational amplifiers has a controllable gain up to 105, a -3 dB bandwidth of 30 kHz, and an equivalent input noise of about 9 nV/(开方Hz). The FES circuit consisting of two-stage operational amplifiers has a bandwidth of more than 10 kHz and a variable gain from 20 dB to 60 dB can provide a current of more than 1 mA to a load of 10 kΩ. They are intended to connect with both cuff-type and stag-type microelectrodes. Integrated circuits (IC) for the neural signal process have been designed with features of low voltage and low power. A more biocompatible composite has been synthesized to modify the silicon and related material.

Objective: The aim of this study was to investigate the competitive adsorption of human albumin (Alb), human fibrinogen (Fib) and human immunoglobulin G (IgG) on surface of biomaterial based on the special molecular recognition and interaction between antigen and antibody with a biomedical sensor Reflectometry Interference Spectroscopy (RIfS). Materials and Methods: The RIfS setup used has been developed in our laboratory (1). The materials to be tested were polyurethane (PU) and polystyrene (PS). The thin films of PU/PS were prepared using a spin-coating method. The thickness of the films was ~650 nm. Three kinds of proteins, Alb, Fib and IgG (Sigma Mo) were used as antigen and three kinds antibody used were sheep anti-human Alb, sheep anti-human Fib and rabbit anti-human IgG. 1. Investigation of interaction between three kinds of proteins alone with special antibodies: At first, the protein adsorption process has been performed as reported in (2). Then, bovine serum albumin (BSA) was added to fill in the areas of the material surface which were not covered by proteins and the PBS flowed over the surface of the PU/PS film to make cleaning. After such a treatment the special antibody solution flowed into the adsorption cell and the kinetic interaction process of antibody with proteins on the surface of the PU/PS film were oberseved in situ on the monitor of a computer. Until the kinitic adsorption curve of antibodies become stable, the PBS was driven into the adsorption cell again to wash off the antibodies which did not firmly adsorpted on the material surface. The wash process would get a response on the adsorption curve. For each kind of proteins, at least three tests were performed. 2. Performance of protein competitive adsorption: At first the protein adsorption process was performed with a mixture of three kinds of proteins (Aib:Fig:IgG=1:1:1). After mixed proteins were competitive adsorbed onto the surface of the PU/PS film, different antibodies were added to measure the interaction between the specific antibodys with each protein in mixed proteins layer adsorbed on the PU/PS film. 3. Caculation of the quantity of each protein in mixed protein layer that competitive adsorbed on the PU/PS: According to the results from 1 and 2, the percent of one kind of proteins in mixed protein layer competitive adsorbed on the surface of the material (Ppx ) was calculated with followed formula: Ppx=(Tp

The quantity and secondary structure of adsorbed albumin (Alb) and immunoglobulin G (IgG) on two kinds of biomaterial surfaces-polyurethane (PU (H50-50)) and polystyrene (PS) were studied using Fourier transform infrared spectroscopy (FTIR). The original spectra tested by FTIR were processed using second-derivation and self-deconvolution techniques to obtain the content of different secondary structures of adsorbed proteins, which could be used to evaluate the denatured degree of proteins. Results showed that the quantity of Alb adsorbed on PU (H50-50) surface is larger than PS. The hydrophobic features of material played a role in conformational change of adsorbed protein, and indicated that the denatured degree caused by hydrophobic PS was greater than hydrophilic PU (H50-50). The blood compatibility of PU (H50-50) was likely to be better than PS.

The purpose of this study is to find out an effective method to prepare natural hydroxyapatite (HA) from biological source, i.e., pig bones, pig teeth, and extracted human teeth. For the preparation of natural HA a calcining method with different temperatures was used, in combination with the thermal gravimetric analysis (TGA). Three analysis methods, i.e., Fourier transform infrared spectroscope (FTIR), X-ray diffraction (XRD), and inductively coupled plasma (ICP) have been used to investigate the characteristics of the prepared materials. The spectrum of the prepared material, obtained by means of FTIR and XRD, are consistent with the standard FTIR spectrum and JCPDS index of XRD of hydroxyapitite. It confirms that the material prepared is hydroxyapitite indeed. The natural HA obtained by calcining at 850℃ shows a desired quality.

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.