Uniform-sized amino-modified silica nanopar-ticles have been prepared by the controlled synchronous hydrolysis of tetraethoxysilane and N-(?amimoethyl)-- aminopropyltriethoxysilane in water nanodroplet of the wa-ter-in-oil microemulsion. These nanoparticles display posi-tive charge potential at definited pH. This is due to the pres-ence of amino groups on the surface of the nanoparticles. Nanoparticles-plasmid DNA complexes can easily form through electrostatical binding between the positive charges of the amino-modified silica nanoparticles and the negative charges of the plasmid DNA. The complexes can be also dis-sociated under alkaline pH or high ionic strength conditions. And enzymatic digestion of the plasmid DNA is almost in-hibited by these nanoparticles complexes. A novel non-viral gene carrier based on the amino-modified silica nanoparti-cles is proposed under the combination of nanotechnology, biotechnology and gene engineering technology. The plasmid DNA can successfully cross various systemic barriers to COS-7 cells as well as mediate high expression of Green Fluorescence Protein (GFP) gene in cells by use of this novel gene carrier.
The routine method for preparation of silica core-shell nanoparticles (NPs) is to carry out nucleation and shell coating through the hydrolysis of silane in water in oil (W/O) microemulsion to form three-dimensional netted silica shell. We found that electrostatic interaction of the core ma- terials with shell materials would determine whether the stable core-shell silica NPs formed or not. The traditional important factors such as molecular weight of core materials or the thickness of the shell have no obvious relationship with it. And the stability of the core-shell silica NPs can be im- proved after changing the electric charge polarity by regu- lating the experiment condition of relevant materials if some core materials cannot be doped inside to form the stable core-shell silica NPs based on the traditional method, which provided experimental and theoretic foundation for prepara- tion and application of the core-shell silica NPs.
HE Xiaoxiao WANG Kemin TAN Weihong CHEN Jiyun DUAN Jinghua YUAN Yin LIN Xia
An effective and fast method for assay of micro-amounts of glucose was set up. A new technique for preparation of enzyme columns based on enzyme immobilization by sol-gel was investigated. Glucose oxidase(GOD) and horseradish peroxidase(HRP) mixed with SiO 2 nanoparticles and polyvinyl butyral(PVB) medium were immobilized on the surface of capillary tube, respectively. The experimental results show that nanoparticles can significantly enhance the catalytic activity of immobilized enzyme. Based on GOD column and HRP column, a liquid droplet sensor was developed for the determination of glucose solution. The effect of separated columns and mixed columns on the response of glucose sensor was investigated. The sensor showed a linear response in a range of 2-400 ng/mL with a detection limit of 0.3 ng/mL under the optimum conditions. The characteristics of the sensor including effect of flow-rate, pH and temperature were discussed.
A new method, molecule wire polymer, was developed for the determination of cyanide based on the competitive reaction. The fluorescence of the molecule wire polymer is quenched due to ion-association with Pd 2+ and restored when cyanide was added into the system. The linear detection range is 5×10 -6—2×10 -4 mol/L and the detection limit is 1×10 -7 mol/L for cyanide under optimal conditions. The possible mechanism of the method was investigated by using absorption spectra. This approach provides a potential useful method for anion detection with a high sensitivity and selectivity.
