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101.
The preparation of biodegradable and thermoresponsive enzyme–polymer bioconjugates with controllable enzymatic activity via reversible addition−fragmentation chain transfer (RAFT) polymerization and amidation conjugation reaction is presented. A new 2-mercaptothiazoline ester functionalized RAFT agent with intra-disulfide linkage was synthesized and used as chain transfer agent (CTA) to generate a biocompatible homopolymer, poly(ethyleneglycol) acrylate (polyPEG-A) and a thermoresponsive copolymer of poly(ethyleneglycol) acrylate with di(ethyleneglycol)ethyl ether acrylate [poly(PEG-A-co-DEG-A)]. These biodegradable and thermoresponsive polymers were then conjugated to the surface of glucose oxidase (GOx) under mild condition to afford the biodegradable and thermoresponsive enzyme–polymer conjugates. Cleavage of the polymer chains from the GOx surface obviously recovered the enzymatic activity. The thermoresponsive test of GOx-poly(PEG-A-co-DEG-A) revealed that the bioconjugate exhibited regular enzymatic activity fluctuation upon the temperature change below or above the lower critical solution temperature (LCST). The as-prepared enzyme–polymer conjugates were also characterized using 1H NMR, UV–vis spectroscopy, polyacrylamide gel electrophoresis (PAGE) and biocatalytic activity tests. These smart enzyme–polymer conjugates would envision promising applications in biotechnology and biomedicine. 相似文献
102.
We describe a rapid and convenient colorimetric method for the detection of oxidative DNA damage caused by peroxynitrite (ONOO?) using unmodified gold nanoparticles (AuNPs). AuNPs are stable in the presence of single-stranded DNA (ssDNA) against the aggregation induced by a high ionic strength. If adsorbed ssDNA are cleaved by ONOO? to form smaller fragments, the AuNPs rapidly aggregate due to electrostatic attraction. As a result, the color of the solution changes from red to blue, and this can be seen with bare eyes. We also have evaluated the activity of the antioxidants gallic acid, ascorbic acid and caffeic acid to scavenge ONOO?. This method therefore also can be applied to screen for anti-oxidation drugs and agents. Figure
ONOO?-induced ssDNA cleavage can be visually detected by a red-to-blue color change of AuNPs. 相似文献
103.
Molecularly imprinted films with self-supporting property (SS-MIFs) have been prepared by using the strategy of transition layer construction followed by reversible addition-fragmentation chain transfer (RAFT) polymerization. The structure, composition and selectivity of the SS-MIFs as well as the mechanism of mass transfer were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform IR spectrometry, specific surface area analysis, thermogravimetric analysis, and HPLC. Surface area analysis showed the samples possessed specific surface areas as high as 80.5 m2.g?1. This is almost 9 times more than that of the original porous anodic aluminum oxide substrate. Thermogravimetric analysis also showed the samples to be thermally stable up to 350 °C. The separating power was investigated by HPLC and revealed a selective separation effect for the target molecules theobromine. The separation factor is 5.37. Figure
Self-supporting molecularly imprinted films (SS-MIFs) have been prepared by the strategy of transition layer construction followed by reversible addition-fragmentation chain transfer polymerization. The obtained samples had high specific surface areas and good recognition selectivity. This synthesis method is facile and the obtained samples had excellent self-supporting performance and better potential use in chemical separation. 相似文献
104.
The self‐assembly of 4 ‐ MTPP [ 4 ‐ MTPP = 2‐(methylthio)‐4‐(pyridin‐4‐yl)pyrimidine] with Cu(NO3)2 and AgNO3 was structurally investigated. For Cu(NO3)2, a discrete mononuclear CuII coordination compound, [Cu( 4 ‐ MTPP )2(NO3)2] ( 1 ), resulted that is exclusively based on Cu–N coordination. For AgNO3, a unique one‐dimensional double‐chain structure ( 2 ) was obtained with the Ag–N distances varying from 2.181(9) to 2.223(9) Å, and the average Ag–S distance being 2.98 Å. Compared to zero‐dimensional 1 , the extension to one‐dimensional 2 is considered to result from the specific affinity between Ag+ and the ligand 4 ‐ MTPP that is attributed to the strong coordinating tendency of silver for aromatic nitrogen and thioether sulfur atoms. 相似文献
105.
The solubility of icariin in the binary solvent system of ethanol and water was measured by UV–Vis spectrophotometry from 288.2 to 328.2 K. The solubility of icariin in the system increased with increasing temperature. A synergistic effect appeared at x 2 = 0.4 (equivalent to 68.34 % ethanol, v/v) binary mixture. Solubility data were correlated with the modified Apelblat equation. The enthalpy and entropy of solution were evaluated using van’t Hoff plots. 相似文献
106.
107.
The novel antifungal hybrid of terbinafine hydrochloride (TER-HCl)/montmorillonite was synthesized by the intercalation method under mechanical stirring. Intercalation of TER-HCl in the MMT galleries was characterized by X-ray diffraction (XRD), Fourier transform infrared spectra, elemental analysis (EA). and thermogravimetric analysis (TGA). The results from IR, TGA, and EA showed a difference in chemical composition of the MMT and the TER-HCl/MMT. XRD analysis showed that the basal spacing of montmorillonite significantly expanded from 1.53 to 2.79 nm. TER-HCl was successfully intercalated into the interlayer of MMT, and 28 % of TER-HCl was released after 48 h in 0.9 % (w/v) NaCl aqueous solution (pH 7) at 37 ± 0.5 °C. The antifungal activity of the hybrid against Candida albicans was evaluated using the inhibitory zone method and the minimum inhibitory concentration. The TER-HCl/MMT strongly inhibited C. albicans. These results show that TER-HCl/MMT can be useful in biomedical applications. 相似文献
108.
建立了一种新型的聚甲基丙烯酸酯类整体柱固相微萃取的样品预处理方法,并与高效液相色谱法联用检测环境水样中的芳香烃。实验采用的固相微萃取材料聚(甲基丙烯酸丁酯-乙二醇二甲基丙烯酸酯)(Poly(BMA-EDMA))对芳香烃类化合物具有较高的萃取效率,优化了萃取时间、盐浓度、解吸时间等条件。5种芳香烃在10~100μg/L的范围内线性关系良好,检出限为0.012~1.316μg/L,相对标准偏差(n=6)为6.5%~18%。用该法分析湖水中的痕量芳香烃,除甲苯外,其他4种芳香烃的加标回收率为90.8%~99.8%。方法适用于快速分析环境水样中的痕量芳香烃。 相似文献
109.
110.
制备了电活化的玻碳电极,利用循环伏安法研究了邻苯二酚和对苯二酚在该电极上的电化学行为,结果表明该电极对两者的氧化还原具有很好的电催化能力。在0.1 mol/L PBS(pH 7.0)中,采用示差脉冲伏安法对对苯二酚和邻苯二酚分别测定和同时测定,对苯二酚和邻苯二酚的氧化峰电流与其浓度分别在3.0×10-7~1.2×10-5 mol/L和1.0×10-7~1.2×10-5 mol/L范围内呈良好的线性关系,检测限分别为1.0×10-7和6.34×10-8mol/L(S/N=3)。该法已用于模拟废水样中对苯二酚和邻苯二酚的测定。 相似文献