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.     

Bruch’s-Mimetic Nanofibrous Membranes Functionalized with the Integrin-Binding Peptides as a Promising Approach for Human Retinal Pigment Epithelium Cell Transplantation

Background: This study aimed to develop an ultrathin nanofibrous membrane able to, firstly, mimic the natural fibrous architecture of human Bruch’s membrane (BM) and, secondly, promote survival of retinal pigment epithelial (RPE) cells after surface functionalization of fibrous membranes. Methods: Integrin-binding peptides (IBPs) that specifically interact with appropriate adhesion receptors on RPEs were immobilized on Bruch’s-mimetic membranes to promote coverage of RPEs. Surface morphologies, Fourier-transform infrared spectroscopy spectra, contact angle analysis, Alamar Blue assay, live/dead assay, immunofluorescence staining, and scanning electron microscopy were used to evaluate the outcome. Results: Results showed that coated membranes maintained the original morphology of nanofibers. After coating with IBPs, the water contact angle of the membrane surfaces varied from 92.38 ± 0.67 degrees to 20.16 ± 0.81 degrees. RPE cells seeded on IBP-coated membranes showed the highest viability at all time points (Day 1, p < 0.05; Day 3, p < 0.01; Days 7 and 14, p < 0.001). The proliferation rate of RPE cells on uncoated poly(ε-caprolactone) (PCL) membranes was significantly lower than that of IBP-coated membranes (p < 0.001). SEM images showed a well-organized hexa/polygonal monolayer of RPE cells on IBP-coated membranes. RPE cells proliferated rapidly, contacted, and became confluent. RPE cells formed a tight adhesion with nanofibers under high-magnification SEM. Our findings confirmed that the IBP-coated PCL membrane improved the attachment, proliferation, and viability of RPE cells. In addition, in this study, we used serum-free culture for RPE cells and short IBPs without immunogenicity to prevent graft rejection and immunogenicity during transplantation. Conclusions: These results indicated that the biomimic BM-IBP-RPE nanofibrous graft might be a new, practicable approach to increase the success rate of RPE cell transplantation.     

Improved Photocatalytic Activity and Stability of Nano‐sized Ag/Ag2CO3 Plasmonic Photocatalyst by Surface Modification of Fe(III) Nanocluster

The surface modification of Ag/Ag₂CO₃ with Fe(III) ions has been achieved through simply photoreduction‐impregnation method. The obtained products were characterized by means of X‐ray diffraction (XRD), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), and UV‐vis absorption spectroscopy. Under visible‐light irradiation (γ>420 nm), the Fe(III)/Ag/Ag₂CO₃ sample displays a higher photocatalytic activity and stability than pure Ag₂CO₃ and Ag/Ag₂CO₃ samples for the degradation of methyl orange (MO). The improved photocatalytic activity and stability of this ternary system could be ascribed to the synergetic effect between Ag nanoparticles and Fe(III) nanocluster. The metallic Ag nanoparticles cause an obviously enhanced visible‐light absorption to produce more photogenerated charges, while the Fe(III) works as an active site for the following oxygen reduction to reduce the recombination rate of photogenerated electrons and holes.     

寡肽自组装纳米材料研究进展

肽类自组装是自然界普遍存在的分子自组装现象之一,研究其自组装行为对理解生命现象、仿生制备以及构建功能材料等具有重要的意义.寡肽由于合成简单,结构组成明确,同时具有良好的生物相容性、可控的降解性,其组装体在药物/基因控制释放、细胞培养、组织工程支架材料及生物矿化等领域具有很大的应用前景.本文概述了近年来寡肽自组装的研究进展,系统介绍了线性和环状寡肽的分子结构设计、自组装体形貌及组装机理以及组装体在生物医学等领域的应用.     

直接硼氢化物燃料电池

直接硼氢化物燃料电池是一种新型的燃料电池,具有理论比能量高,产物清洁无污染,燃料易于储存和运输等特点,可广泛应用于小型便携式电子产品和移动电源,近年来受到越来越多研究者的关注。本文在介绍了直接硼氢化物燃料电池工作原理的基础上讨论了阳极催化剂、阴极催化剂的研究进展,并探讨了电解液和温度等条件对电池性能的影响,简要分析了发展直接硼氢化物燃料电池面临的主要问题。     

彩虹全息图的假彩色编码方法

本文在三基色原理的基础上，分析了在彩虹全息术中的两种假彩色编码方法——多狭缝假彩色编码方法和参考光假彩色编码方法。     

红外激光照射对立方体AgBr l颗粒离子电导的影响

经硫醚、二氧化硫脲、金、硫醚加金和二氧化硫脲加金增感后的立方体AgBrⅠ乳剂用Nd:YAG激光的基频输出(1064nm,445mJ/cm²)照射后,乳剂的离子电导率比未照射时增加几倍,并且二氧化硫脲增感后的乳剂离子电导率也显着增加。这些结果表明,进一步的研究有助于阐明红外预增感成像机理。     

内敏乳剂的感光性能和离子性能

本文研究了内核经硫加金增感的内敏核壳乳剂的感光性能和离子性能。内核化学增感时Na₂S₂O₃和AuCl₃两者的加入量按一定比例增大时,内部感光度升高,表面感光度下降,离子电导率略有降低。内核化学增感时如果单独增加AuCl₃的用量,内部感光度有所升高,表面感光性能基本不变,离子电导率略有下降。内核化学增感结束引入稳定剂583,可使内显灰雾明显降低,离子电导率也有所下降,核壳比增大造成内部感光度上升而表面感光度下降,离子电导率也有所下降。表面引入碘后,离子电导率明显上升。     

照相明胶与化学增感剂相互作用的XPS研究

本文采用X射线光电子能谱技术研究了两种照相明胶与化学增感剂相互作用的机理.当两种照相明胶样品在HAuCl₄溶液中反应5min后,明胶中的蛋氨酸、蛋氨酸亚砜均被氧化为蛋氨酸砜.与此同时,明胶吸附的大部分Au³⁺被还原为Au⁺,并且Au⁺以络合形态存在于明胶之中.根据与AuCl₃反应之后明胶中Au³⁺与Au⁺的比例,法国明胶的还原性略高于包头明胶.添加到明胶中的Na₂S₂O₃能将明胶大分子所含的蛋氨酸亚砜全部还原为蛋氨酸.S₂O₃^2-、蛋氨酸和蛋氨酸砜可以稳定共存于明胶体系之中,外加的S₂O₃^2-的还原性高于明胶中蛋氨酸、蛋氨酸亚砜的还原性.添加Na₂S₂O₃后的两种照相明胶均可以将其溶胀吸附的Au³⁺全部还原为胶态金.此时,参与氧化还原反应的主要基团是S₂O₃^2-而非明胶中的蛋氨酸残基.由于Na₂S₂O₃的添加,照相明胶对AuCl₃的还原能力增强.     

冻存人淋巴细胞凝集的成因分析

本文对长期冻存的人外周血淋巴细胞的细胞膜形态和功能变化及其与细胞凝集的关系进行了研究,并对凝集的成因作了分析,初步提出了降低凝集作用的综合措施. 采用含to劣二甲基亚矾和40}人AB型血清的RPMI 164。培养液作为冻存液,将淋巴细胞在液氮中冻存1年,复温后,检测其存活率,细胞凝集现象和细胞电泳速率,并观察了细胞表面超微结构的变化. 冻存淋巴细胞复苏后,部分细胞呈现凝集状态,这是由于细胞膜结构和功能受到损伤所致,表现在细胞表面净负电荷密度的降低,电泳率减缓,细胞轻度皱缩,膜表面微绒毛增粗,出现粗大的指状突起.二甲基亚讽是造成膜结构与功能变化的一个重要因素,在常温下更加明显,它具有较强的促凝集作用.此外,淋巴细胞悬液内混杂血小板,也是促进细胞凝集的因素.