Multicolor Tunable Emission from Organogels Containing Tetraphenylethene,Perylenediimide, and Spiropyran Derivatives

A dendron‐substituted tetraphenylethene low molecular weight gelator (LMWG)compound, LMWG 1, is designed and investigated. Gelation‐induced fluorescence enhancement is observed for the gel based on LMWG 1 and its fluorescence can be reversibly tuned by varying the temperature of the ensemble. The photoinduced energy‐transfer can occur between LMWG 1 and PI 2 (perylene diimide) in the gel phase, but it cannot occur in the corresponding solution. The emission color of the gel of LMWG 1 and PI 2 can be tuned from cyan, yellow, to red by varying the concentration of PI 2 . By taking advantage of the photochromic transformation of spiropyran, the emission color of the organogels based on LMWG 1 and SP 3 can be switched by alternating UV and visible‐light irradiations. The emission color can also be tuned by varying the irradiation time. In this way, organogels based on LMWG 1 with multiemission color can be achieved in the presence of SP 3 after light irradiations.     

Adhesion and Mechanical Properties of PNIPAM Microgel Films and Their Potential Use as Switchable Cell Culture Substrates

Thermoresponsive poly(N‐isopropylacrylamide) (PNIPAM) microgel films are shown to allow controlled detachment of adsorbed cells via temperature stimuli. Cell response occurs on the timescale of several minutes, is reversible, and allows for harvesting of cells in a mild fashion. The fact that microgels are attached non‐covalently allows using them on a broad variety of (charged) surfaces and is a major advantage as compared to approaches relying on covalent attachment of active films. In the following, the microgels’ physico‐chemical parameters in the adsorbed state and their changes upon temperature variation are studied in order to gain a deeper understanding of the involved phenomena. By means of atomic force microscopy (AFM), the water content, mechanical properties, and adhesion forces of the microgel films are studied as a function of temperature. The analysis shows that these properties change drastically when crossing the critical temperature of the polymer film, which is the basis of the fast cell response upon temperature changes. Furthermore, nanoscale mechanical analysis shows that the films posses a nanoscopic gradient in mechanical properties.     

pH‐Activated Near‐Infrared Fluorescence Nanoprobe Imaging Tumors by Sensing the Acidic Microenvironment

Imaging tumors in their early stages is crucial to increase the surviving rate of cancer patients. Currently most fluorescence probes visualize the neoplasia by targeting the tumor‐associated receptor over‐expressed on the cancer cell membrane. However, the expression level of these receptors in vivo is hard to predict, which limits their clinical translation. Furthermore, the signal output of these receptor‐targeting probes usually stays at a high level, which leads to a strong background signal in normal tissue due to non‐specific binding. In contrast to receptors, characteristics of the tumor microenvironment – such as acidosis – are pervasive in almost all solid tumors and can be easily accessed. In this work, a novel biodegradable nanoprobe InNP1 that demonstrates pH‐activated near‐infrared (NIR) fluorescence in both human glioblastoma U87MG cancer cells in vitro and the subcutaneous U87MG tumor xenografts in vivo is developed. Bio‐distribution, in vivo optical imaging, and autoradiography studies demonstrate that the pH‐activated NIR fluorescence is the dominant factor responsible for the high tumor/normal tissue (T/N) ratio of InNP1 in vivo. Overall, the work provides a nanoprobe prototype to visualize the solid tumor in vivo with high sensitivity and minimal systemic toxicity by sensing the tumor acidic microenvironment.     

Transparent Polysilsesquioxane Films Obtained from Bridged Ureasil Precursors: Tunable Photoluminescence Emission in the Visible Region and Filtering of UV‐Radiation

Bridged ureasil precursors were synthesized by the reaction of either ethylenediamine (1 mol) or m‐xylylenediamine (1 mol) with isocyanatepropyltriethoxysilane (2 mol). Transparent polysilsesquioxane films were obtained by the hydrolytic condensation of the pure precursors or their co‐condensation in a 50:50 molar ratio. Films based on pure ureasil precursors showed a blue photoluminescent emission band assigned to the photoinduced proton‐transfer among H‐bonded urea groups and the subsequent radiative recombination of ionized groups. Films synthesized by the co‐condensation of both precursors exhibited a significant red‐shift of their absorption, excitation, and emission spectra, associated to de‐localization of H‐bonds, and a high absorption of UV‐radiation.

     

Interaction of CO dehydrogenase with the cytoplasmic membrane monitored by fluorescence correlation spectroscopy

We have investigated the interaction of carbon monoxide dehydrogenase (CODH), an enzyme that catalyses the oxidation of CO in the aerobic eubacterium Oligotropha carboxidovorans, with the cytoplasmic membrane by using fluorescence correlation spectroscopy (FCS). Our results reveal that in vitro this interaction of CODH is specific for cytoplasmic membranes from CO-grown bacteria.     

Cellular Internalization of Water‐Soluble Helical Aromatic Amide Foldamers

The intracellular transport of drugs and therapeutics represents one of the most exciting and challenging areas at the interface of chemistry, biology, and medicine. Most of the effort in this field so far has been devoted to the development of peptide‐based delivery systems that can translocate therapeutic agents into their intracellular targets. More recently, the use of bioinspired non‐natural foldamers has resulted in the successful delivery of cargo molecules, which possess a wide range of sizes and physicochemical properties across the cell membrane. We report herein the synthesis of aromatic amide foldamers and their biological evaluation as cell‐penetrating agents. By using a well‐established synthetic route, a series of fluorescein‐labeled cationic aryl amide conjugates has been constructed, and their cellular uptake into various human cell lines has been analyzed by flow cytometry and fluorescence microscopy. The assays revealed that longer oligomers achieve greater cellular translocation, with octamer Q8 proving to be a remarkable vehicle for all three cell lines. Biological studies have also indicated that these helices are biocompatible, thus showing promise in their application as cell‐penetrating agents and as vehicles to deliver biologically active molecules into cells.     

活性炭纤维吸附邻硝基苯胺水溶液的研究

采用活性炭纤维(ACF)处理邻硝基苯胺模拟废水,通过静态和动态吸附实验,研究了pH、盐含量、吸附时间对吸附效果的影响,测定了吸附等温线和动态穿透曲线,并进行了ACF再生实验。结果表明,在实验条件下,ACF对邻硝基苯胺的吸附速率很快,5 min去除率达96%,在pH4.4~10.4条件下吸附效果较好,盐的含量对吸附效果影响较小,吸附等温线能用Langmuir和Freundlich方程较好地拟合。溶液流速增大,穿透时间提前,吸附饱和的ACF用无水乙醇再生,重复5次,邻硝基苯胺的回收率均在95%以上,ACF的吸附效率无明显变化。     

活性炭部分指标对烟气中低分子醛酮类物质含量的影响

将添加不同pH值、比表面积和水分含量活性炭的复合滤嘴卷烟在标准条件下进行抽吸,利用2,4-二硝基苯肼溶液收集主流烟气,高效液相色谱法分析卷烟主流烟气中低分子醛酮类物质含量,研究了pH值、比表面积和水分含量对活性炭吸附作用的影响。结果表明,活性炭pH值由5~7增加到7~9、比表面积由800 m2/g增加到1 200 m2/g时,低分子醛酮类物质总量分别下降13.0%,20.9%;水分含量由6%增加到10%时,低分子醛酮类物质总量分别为685.59,685.88μg/支。pH值和比表面积是影响活性炭对低分子醛酮类物质吸附作用的重要因素。