[Preparation of poly(methyl acrylate) microfluidic chips surface-modified by hyperbranched polyamide ester and their application in the separation of biomolecules].

The surface of poly (methyl acrylate) (PMMA) microfluidic chips were modified using hyperbranched polyamide ester via chemical bonding. The contact angles of the modified chips were measured. The surface morphology was observed by scanning electron microscope (SEM) and stereo microscope. The results showed that the surface of the modified chips was coated by a dense, uniform, continuous, hydrophilic layer of hyperbranched polyamide ester. The hydrophilic of the chip surface was markedly improved. The contact angle of the chips modified decreased from 89.9 degrees to 29.5 degrees. The electro osmotic flow (EOF) in the modified microchannel was lower than that in the unmodified microchannel. Adenosine and L-lysine were detected and separated via the modified PMMA microfluidic chips. Compared with unmodified chips, the modified chips successfully separated the two biomolecules. The detection peaks were clear and sharp. The separation efficiencies of adenosine and L-lysine were 8.44 x 10(4) plates/m and 9.82 x 10(4) plates/m respectively, and the resolutions (Rs) was 5.31. The column efficiencies and resolutions of the modified chips were much higher than those of the unmodified chips. It was also observed that the modified chips possessed good reproducibility of migration time. This research may provide a new and effective method to improve the hydrophilicity of the PMMA surface and the application of PMMA microfluidic chips in the determination of trace biomolecules.

[Preparation of capillary electrophoresis column physically coated with hyperbranched polyesters and its application in the separation of basic proteins].

Two series of hyperbranched polyesters were synthesized using pentaerythritol as the core by one-step and pseudo-step procedures. The molecular structures of the hyperbranched polyesters were characterized using infrared spectrum and hydroxyl value. Due to their low viscosity, the hyperbranched polyesters were easily coated on the inner surface of the fused-silica capillary by physical adsorption. The adsorption behavior of this capillary electrophoresis column coated with polyesters was investigated by the separation of three basic proteins. The electro-osmotic flow and the capability for the separation of the basic proteins were studied. It was found that the coatings of hyperbranched polyesters could significantly reduce the electroosmotic flow and suppress the protein adsorption onto the inner surface of the fused-silica capillaries in the pH range of 3.0-7.0. Three basic proteins were effectively separated at pH=5 on the column coated with the hyperbranched polyesters, with the separation efficiency being 10(5) plates/m. The experimental results also showed that the separation efficiency and the resolution on columns coated with hyperbranched polyesters by pseudo-step procedure were much better than those by one-step procedure.

[Atomic emission spectrometry determination of Au, Pt and Pd after separation and enrichment by hyperbranched polymer].

The present paper shows that the trace amount of gold, platinum and palladium in hydrochloric acid solution can be concentrated by hyperbranched polymer. The new reagent has a rapid adsorption rate and big concentrating capacity. The determination of trace Au, Pt and Pd in sample using carbon powder and strontium carbonate as buffer was carried out by atomic emission spectrometry(AES). Zirconium was selected as internal standard line. The sample was directly loaded into ordinary electrode. The method is simple, rapid and accurate. The condition of determination, and factors of influence were studied. The analysis line of Au, Pt and Pd is 312.3, 306.5 and 311.4 nm respectively. The internal standard line of Zr is 310.7 nm. The linear range of the determination of Au, Pt and Pd is 0-0. 20%, 0-0. 40% and 0-0. 20% respectively. The detection limit of Au, Pt and Pd is 0.010%, 0.0030% and 0.0030% respectively. The method has been applied to the determination of Au, Pt and Pd with satisfactory results.

Preparation and evaluation of non-bonded hyperbranched polymer-coated columns for capillary electrophoresis.

A series of hyperbranched poly(amine-ester)s based on 1,1,1-trimethylolpropane, methyl acrylate and diethanolamine were synthesized and coated on the inner surface of the fused-silica capillaries by physical adsorption. The most effective coating was the seventh generation hyperbranched poly(amine-ester) coating, which reduced the electroosmotic flow (EOF) greatly and suppressed protein adsorption effectively. The high separation efficiencies for basic proteins were obtained and the coating had a good stability.

[The preparation of chemical-bonded hyperbranched polymer coated column for capillary electrophoresis and their application to separation of basic proteins].

A series of hyperbranched poly(amine-ester)s were synthesized using one-step and pseudo-step procedure respectively, and their molecular structures were characterized by IR, hydroxyl value and viscosity. These polymers were coated on the inner surface of the fused-silica capillaries in a chemical bonding process. The electroosmotic flow and the separation capability for basic proteins of the coated capillaries were investigated. The results demonstrated that the coating in the capillaries could greatly reduce the electroosmotic flow and effectively suppress protein adsorption in the pH range of 3-7. The separation efficiency of the coated capillary of hyperbranched poly(amine-ester)s with trimethylolpropane and pentaerythritol as the core was 10(5)/m and 10(7)/m, respectively. The separation efficiency and the stability of basic proteins on these coated capillaries were found excellent.