Nonfouling polypeptides with homogenous alternating charges draw peoples’ attentions for their potential capability in biodegradation. Homogenous glutamic acid (E) and lysine (K) polypeptides were proposed and synthesized before. In this work, a new polypeptide formed by poly(glutamic acid) with lysine side chains (poly(E)-K) was synthesized by facile EDC·HCl/HOBt chemistry and investigated. Results show that these polypeptides also have good nonspecific protein resistance determined by enzyme-linked immunosorbent assay. The lowest nonspecific adsorption of the model proteins, anti-IgG and fibrinogen (Fg), on the self-assembling monolayers (SAMs) surface of poly(E)-K was only 3.3 ± 1.8 and 4.4 ± 1.6%, respectively, when protein adsorption on tissue culture polystyrene surface was set as 100%. And, the relative nonspecific protein adsorption increases when the polypeptide molecular weight increases due to the repression of low density polymer brushes. Moreover, almost no obvious cytotoxicity and hemolytic activity in vitro were detected. This work suggests that polypeptides with various formats of homogenous balanced charges could achieve excellent nonspecific protein resistance, which might be the intrinsic reason for the coexistence of high concentration serum proteins in blood.
Yang Zuoyi,Mao Xingchen,Cui Jiahao,Wang Yujie,Zhang Yaping
This study examines the specific effect of Tween 80 on the conversion of anthracene (ANT) in laccase medium system regarding surfactant chemical changes and mechanism. The conversion rate and degradation products of ANT were investigated in different concentrations of Tween 80 solution. Between Tween 80 concentration 0–40 critical micelle concentrations (CMC), the kinetic parameter-k (h −1 ) and corresponding half-life T 1/2 decreased with increasing concentration. When Tween 80 was above 20 CMC the laccase-medium system converted > 95% of ANT to anthraquinone within 12 h. During the entire enzymatic reaction, the laccase activity in the system increased with increasing Tween 80 concentration. Combined with GC/MS analysis of the product, it was speculated that hydrogens belonging to the ether-oxygen bond and carbon–carbon double bond α-CH of Tween 80, were removed by the laccase-media system, promoting its degradation. Additionally, enhanced activity caused by oxygen free radicals (ROS) such as RO• and ROO•, continuously oxidized Tween 80, which in turn produced free radicals while converting ANT. This study provides new theoretical support toward the application of surfactants in the elimination of polycyclic aromatic hydrocarbons.
Yunkai Sun,Xiaoxia Wu,Meng Cao,Xiaoqiang Xue,Dongfang Jiang,Zhao Liu
In the classical route of synthesizing of avanafil, the last step of the reaction uses EDCI and HOBT as an acid and amine binding agent. HOBT may contain residues of hydrazine, and potential mutagenic impurities containing acylhydrazide structures may be formed. The intermediate product (M6) of avanafil was synthesized by 6 steps using diethyl ethoxylmethylmalonate and S-methyl isothiourea semisulfide as starting materials. The potentially genotoxic impurity E (Imp-E) of avanafil was given by the reaction of M6 and hydrazine sulfate acid amine, yield of 20%. The single crystal of Imp-E was cultivated by solvent volatilization method, and its structure was analyzed by high resolution mass spectrometry (HRMS) and nuclear magnetic resonance spectroscopy (NMR). The Flack parameter of Imp-E was -0.03(3) by X-ray single crystal diffraction analysis, and the absolute configuration of Imp-E was determined as S configuration. The intramolecular / intermolecular hydrogen bonds of Imp-E make the molecules maintain a stable arrangement in space.
危险品化学品经营许可证（带存储）