[FTIR spectra study on the film of polyurethane coated urea controlled-release fertilizer].

The polyurethane films were prepared to wrap the urea in order to achieve a desirable release rate by mixing isocyanate, polyols and wax. The effect of wax, urea and isocyanate on the structure and properties of the films was investigated by FTIR. The structural changes were monitored as the polyurethane films together with the wrapped urea were immersed into ammonia water for 28 days, which is used to model soil conditions. The FTIR results showed that the width and intensity of the NH-free band increased remarkably with time, and all kinds of carbonly bands shifted to high wavenumber and their intensity increased obviously. The results suggest that the structure of the polyurethane films was destroyed more heavily in soil than in water, and this explains the relatively fast release rate of urea in soil. It was observed that the increase in the chemical crosslinking density in the polyurethane films can effectively decrease the release rate of the urea nitrogen in soil.

[Mutation analysis of the eda-A1 gene for hypohidrotic ectodermal dysplasia and construction of recombined eukaryotic expression vector].

OBJECTIVE: The purpose of this study was to clone and analyze mutation in the eda-A1 gene for hypohidrotic ectodermal dysplasia (HED), and to construct a new recombined eukaryotic expression vector (mutant M, wild W) as a basis for further study on the genetic function. METHODS: After total mRNA was extracted from peripheral blood lymphocytes from the HED affect patient and control, eda-A1 gene was amplified by reverse transcription polymerase chain reaction (RT-PCR) with a pair of specific primers containing the constriction enzyme sites of BamH I and Hind III. When the vector pcDNA3.1(-) and eda-A1 (M/W) were digested by BamH I and Hind III respectively, eda-A1 (M/W) fragment was then ligated to vector pcDNA3.1 (-) and the new vector was named as pcDNA3.1 (-)-eda-A1-M/W. RESULTS: eda-A1 gene was successfully cloned and a novel missence mutation was identified, which changes the codon 306 from glutamine to proline. PCR, restrictive endonuclease analysis and DNA sequencing were then performed to identify the recombinant eukaryotic expression vector pcDNA3.1 (-)-eda-A1-M/W, and the results were surely confirmed. CONCLUSION: Our result indicates that the novel missense mutation in eda is associated with the isolated tooth agenesis and provide preliminary explanation for the abnormal clinical phenotype at a molecular structural level. And also, the recombinant eukaryotic expression vector pcDNA3.1 (-)-eda-A1-M/W was successfully constructed, which will be thereafter taken use of further study on eda gene in odontogenesis.

Controlled immobilization of chondroitin sulfate in polyacrylic acid networks.

Novel semi-interpenetrating polymer networks (semi-IPNs) of chondroitin sulfate (ChS) and acrylic acid (AA) were prepared with the aim of obtaining a hydrogel for use as a colon-specific drug carrier. By controlling the concentrations of cross-linking agent, diethylene glycol dimethacrylate (DEGDA), as well as the reaction solvent, high swelling percentages were obtained (approx. 1600%). However, the highest sol percent obtained for these hydrogels was approx. 70%, and most of the chondroitin sulfate remained soluble and could be extracted. Therefore, an alternative approach was adopted: methacrylate-grafted ChS (ChSMA) was synthesized and then co-polymerized with acrylic acid (AA) at a molar ratio of 1:5 with various concentrations of AA. The sol content of these ChSMA-AA hydrogels was reduced to approx. 20%, and the cross-linking densities were almost 100-fold higher than those of the semi-IPNs. FT-IR spectra showed that the H-bonding interactions between ChS and PAA and the spectra of the semi-IPNs were similar to that of PAA itself after sol extraction. In contrast, the FT-IR spectra of ChSMA-AA remained intact after sol extraction. Ketoprofen was used as a model drug to test the sustained release behavior of these hydrogels.