External-Radiation-Induced Local Hydroxylation Enables Remote Release of Functional Molecules in Tumors

Radiation-induced cleavage for controlled release in vivo is yet to be established. We demonstrate the use of 3,5-dihydroxybenzyl carbamate (DHBC) as a masking group that is selectively and efficiently removed by external radiation in vitro and in vivo. DHBC reacts mainly with hydroxyl radicals produced by radiation to afford hydroxylation at para/ortho positions, followed by 1,4- or 1,6-elimination to rescue the functionality of the client molecule. The reaction is rapid and can liberate functional molecules under physiological conditions. This controlled-release platform is compatible with living systems, as demonstrated by the release of a rhodol fluorophore derivative in cells and tumor xenografts. The combined benefits of the robust caging group, the good release yield, and the independence of penetration depth make DHBC derivatives attractive chemical caging moieties for use in chemical biology and prodrug activation.     

Degradation of Structurally Defined Graphene Nanoribbons by Myeloperoxidase and the Photo-Fenton Reaction

As an emerging member of the graphene family, structurally defined graphene nanoribbons (GNRs) have shown promising applications in various fields. The evaluation of the degradability of GNRs is particularly important for assessing the persistence level and risk of these materials in living organisms and the environment. However, there is a void in the study of the degradation of GNRs. Here, we report the degradation behavior of GNRs in the presence of human myeloperoxidase (hMPO) or treated with the photo-Fenton (PF) reaction. With the assistance of potassium hydroxide or imidazole, which facilitates the dispersion of GNRs in the aqueous solution, GNRs underwent only partial degradation after 25-hour incubation with hMPO, while, the PF reaction degraded GNRs almost completely after 120 hours. These results indicate that structurally precise GNRs can be efficiently degraded under suitable conditions, providing more opportunities for future applications in different fields.     

活性炭纤维电极生成羟基自由基降解酸性红B

分别采用具有吸附催化性能的活性炭纤维(ACF)作为阳极和阴极对水中偶氮染料酸性红B (ARB)的电化学降解情况进行了系统研究. 研究表明两种体系均可较好降解ARB, 可达到色度完全去除, 但ACF作为阴极电芬顿对有机物的矿化程度远远高于以ACF作为阳极时的矿化程度, 其TOC去除率达到70%, 高于阳极体系的30% TOC去除率. 通过电子自旋捕集技术(ESR)检测两种反应体系中产生的活性中间体, 发现在两种体系中均有高活性的羟基自由基生成, ACF阴极体系中产生的羟基自由基的量远远高于阳极体系产生量, 这是阴极体系有机物矿化效果较好的根本原因. 还对电流强度和初始pH的影响进行了研究, 并对两个体系反应机理进行了讨论.     

采用循环伏安与Tafel曲线比较不同阳极的电催化性能

采用循环伏安和Tafel曲线两种方法评价了Pt电极、钛基二氧化钌电极(Ti/RuO2)及钛基二氧化锡电极(Ti/SnO2)的电催化氧化性能.结果表明,在500 mg/L的苯酚溶液中,Pt,Ti/RuO2和Ti/SnO2电极氧化苯酚的峰电位依次为0.93,0.95和1.40 V(vsAg/AgCl).Tafel曲线表明,三种电极析氧过电位的顺序依次是Ti/RuO2相似文献   

羟自由基对支撑磷脂双层膜的破坏及水溶性抗氧化剂保护作用的电化学研究

以支撑磷脂双层膜(supported bilayer lipid membrane, s-BLM)作为生物膜模型, 利用Fenton体系产生羟自由基(hydroxyl free radical, •OH), 采用循环伏安法研究了s-BLM与•OH之间的相互作用. 结果表明: •OH通过与磷脂发生化学反应, 诱发s-BLM上形成孔洞或缺陷, 这种作用对时间、FeSO₄和H₂O₂的浓度具有依赖性, 且不可恢复. 具有还原性基团的抗氧化剂维生素C, 还原型谷胱甘肽和L-半胱氨酸, 通过与•OH发生氧化还原反应, 可抑制•OH与s-BLM的相互作用, 降低•OH对s-BLM结构的破坏程度.     

Fe3+-H2O2-Rh6G化学发光体系测定水中的邻苯二酚

酚类化合物对于人体及其他生物的毒性较大,邻苯二酚作为一种重要的有机化工原料和中间体,在农业、染料、香料、橡胶、医药、感光材料等领域具有广泛的应用。因此监测废水中邻苯二酚的含量是控制水环境质量的一个重要指标。目前测定邻苯二酚的方法主要有光度法[1,2],原子吸收法[     

The mechanism and pathway of the ozonation of 4-chlorophenol in aqueous solution

Chlorophenols (CPs) have been widely used in dif- ferent formulations as preservatives, herbicides, insec- ticides, bactericides and solvents. Parts of chlorophe- nols were released to the natural environment during the usage. As a result, many water sources were con- taminated with CPs[1,2]. Furthermore, they also can be formed during the disinfection of phenol containing water by chlorination. Several CPs are recognized as the priority pollutants by the United States EPA (En- vironmenta…     

含羟基和咪唑基团新手性肽核酸的设计与合成

以含丝氨酸和组氨酸残基的手性肽核酸单体替换经典肽核酸单体, 采用固相合成方法设计合成了五个新序列含羟基和咪唑基团的10聚体手性肽核酸, 经ESI-MS或MALDI-TOF-MS证实目标物结构正确.     

Influence of ion-exchange and impregnation modification of zeolite X on its catalytic properties in the alkylation of toluene with methanol

The dependence of the activity and selectivity of ion-exchanged forms of zeolite X with incorporated cesium process in alkylation of toluene with methanol in the side chain on the nature of the ion-exchanged cations (Na⁺, Cs⁺, Mg²⁺, Zn²⁺) has been established. It is shown that introduction of Mg²⁺ and Zn²⁺ in combination with Cs₂CO₃ significantly increased the yields of ethylbenzene and styrene in comparison with their yields on alkali forms of zeolite X. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 33–38, January–February, 2006.     

不同加成数C60精氨酸衍生物的合成及其清除活性氧自由基的性能

通过控制反应配比, 首次合成了三种具有不同加成数目的水溶性C₆₀精氨酸衍生物, C₆₀[HNC(NH)NH(CH₂)₃CH(NH₂)COOH]_nH_n (n＝2, 6, 8). 采用FT-IR, UV, RF, ¹H NMR, ¹³C NMR, LC-MS, EA, 粒径分析, 透射电镜等手段对其结构进行了表征. 同时采用化学发光法考察了三种具有不同加成数目的C₆₀精氨酸衍生物对活性氧自由基(超氧阴离子O₂^－.及羟自由基•OH)清除能力, 结果表明, C₆₀精氨酸衍生物对活性氧自由基具有优良的清除能力, 且清除能力与加成基团供电效应、空间位阻及C₆₀精氨酸衍生物在水中的聚集形态等因素密切相关.