排序方式: 共有78条查询结果,搜索用时 15 毫秒
21.
Aathimanikandan SV Savariar EN Thayumanavan S 《Journal of the American Chemical Society》2005,127(42):14922-14929
Syntheses up to three generations have been achieved of biaryl-based amphiphilic dendrons with a charge-neutral pentaethylene glycol as the hydrophilic part and a decyl chain as the hydrophobic part. Studies on the temperature-dependent characteristics revealed that these dendrons exhibit a generation-dependent lower critical solution temperature (LCST). This behavior is attributed to the combination of the amphipathic nature of the hydrophilic pentaethylene glycol side chain and dendritic effect. Interestingly, this biaryl-based scaffold also maintains the ability to form a micelle-like assembly in polar solvents and an inverted micelle-like assembly in apolar solvents. Polarity of the dendritic interior was investigated using dye-based microenvironment studies. The aggregation behavior of these micelles was analyzed by fluorescence spectroscopy and dynamic light scattering. Critical micelle concentrations (CMC) of these assemblies were investigated using fluorescence excitation spectra of the sequestered guest molecule, pyrene. 相似文献
22.
Basu S Vutukuri DR Shyamroy S Sandanaraj BS Thayumanavan S 《Journal of the American Chemical Society》2004,126(32):9890-9891
Stimuli-responsive polymers and assemblies are viable candidates for the so-called "smart" materials. In this communication, we report a new class of amphiphilic homopolymers that forms micelle-like structures in polar solvents and inverted micelle-like structures in apolar solvents. We demonstrate that these superstructures are the result of the changes in the molecular-level conformations in the monomer. 相似文献
23.
[structure: see text] A methodology for synthesizing dendrons with different peripheral functionalities is described. The benzyl ether-based dendrons reported here were synthesized using allyl and methoxymethyl ether-based protection-deprotection strategies. 相似文献
24.
Rajasekhar R. Ramireddy Dr. Ayyagari V. Subrahmanyam Prof. S. Thayumanavan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(48):16374-16381
Supramolecular nano‐assemblies that reduce nonspecific interactions with biological macromolecules, such as proteins, are of great importance for various biological applications. Recently, zwitterionic materials have been shown to reduce nonspecific interactions with biomolecules, owing both to their charge neutrality and their ability to form a strong hydration layer around zwitterions via electrostatic interactions. Here, new triazole‐based zwitterionic moieties are presented that are incorporated as the hydrophilic functionalities in facially amphiphilic dendrons. The amphiphilic zwitterionic dendrons spontaneously self‐assemble in aqueous solutions forming micelle‐type aggregates, which were confirmed by DLS, TEM, and fluorescence techniques. The structural and functional characteristics of the zwitterionic dendrons are also compared with the corresponding charge‐neutral PEG‐based dendrons and anionic carboxylate‐based dendrons. Surface‐charge measurements, temperature sensitivity and evaluation of interactions of these assemblies with proteins form the bases for these comparisons. 相似文献
25.
Jingjing Gao Peidong Wu Ann Fernandez Jiaming Zhuang S. Thayumanavan 《Angewandte Chemie (International ed. in English)》2020,59(26):10456-10460
The development of nanoparticle‐based biomedical applications has been hampered due to undesired off‐target effects. Herein, we outline a cellular AND gate to enhance uptake selectivity, in which a nanoassembly–cell interaction is turned on, only in the concurrent presence of two different protein functions, an enzymatic reaction (alkaline phosphatase, ALP) and a ligand–protein (carbonic anhydrase IX, CA IX) binding event. Selective uptake of nanoassemblies was observed in cells that overexpress both of these proteins (unicellular AND gate). Interestingly, selective uptake can also be achieved in CA IX overexpressed cells, when cocultured with ALP overexpressed cells, where the nanoassembly presumably acts as a mediator for cell–cell communication (bicellular AND gate). This logic‐gated cellular uptake could find use in applications such as tumor imaging or theranostics. 相似文献
26.
Linear polymers have been considered the best molecular structures for the formation of efficient protein conjugates due to their biological advantages, synthetic convenience and ease of functionalization. In recent years, much attention has been dedicated to develop synthetic strategies that produce the most control over protein conjugation utilizing linear polymers as scaffolds. As a result, different conjugate models, such as semitelechelic, homotelechelic, heterotelechelic and branched or star polymer conjugates, have been obtained that take advantage of these well-controlled synthetic strategies. Development of protein conjugates using nanostructures and the formation of said nanostructures from protein–polymer bioconjugates are other areas in the protein bioconjugation field. Although several polymer–protein technologies have been developed from these discoveries, few review articles have focused on the design and function of these polymers and nanostructures. This review will highlight some recent advances in protein-linear polymer technologies that employ protein covalent conjugation and successful protein-nanostructure bioconjugates (covalent conjugation as well) that have shown great potential for biological applications. 相似文献
27.
Smart Organic Two‐Dimensional Materials Based on a Rational Combination of Non‐covalent Interactions
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Dr. Wei Bai Ziwen Jiang Dr. Alexander E. Ribbe Prof. S. Thayumanavan 《Angewandte Chemie (International ed. in English)》2016,55(36):10707-10711
Rational design of organic 2D (O2D) materials has made some progress, but it is still in its infancy. A class of self‐assembling small molecules is presented that form nano/microscale supramolecular 2D materials in aqueous media. A judicial combination of four different intermolecular interactions forms the basis for the robust formation of these ultrathin assemblies. These assemblies can be programmed to disassemble in response to a specific protein and release its non‐covalently bound guest molecules. 相似文献
28.
Gomez-Escudero A Azagarsamy MA Theddu N Vachet RW Thayumanavan S 《Journal of the American Chemical Society》2008,130(33):11156-11163
Amphiphilic dendrimers, which contain both hydrophobic and hydrophilic groups in every repeat unit, exhibit environment-dependent assemblies both in hydrophilic solvent, water, and in lipophilic solvent, toluene. Upon investigating the status of these assemblies in a mixture of immiscible solvents, these dendrimers were found to be kinetically trapped in the solvent in which they are initially assembled. This property has been exploited to selectively extract peptides from aqueous solution into an organic phase, where the peptides bind to the interior functionalities of the dendritic inverse micelles. While the corresponding small molecule surfactant does not exhibit any selective binding toward peptides, all dendrons (G1-G3) are capable of this selective binding. We show that the inverse micelle-type assembly itself is crucial for the binding event and that the assembly formed by the G1 dendron has a greater capability for binding compared to the G2 or G3 dendrons. We have also shown that the average apparent pKa of the carboxylic acid functionalities varies with generation, and this could be the reason for the observed differences in binding capacity. 相似文献
29.
Nagamani C Viswanathan U Versek C Tuominen MT Auerbach SM Thayumanavan S 《Chemical communications (Cambridge, England)》2011,47(23):6638-6640
The dynamic nature of hydrogen bonds in phenolic polymers, where the hydrogen bond donor/acceptor reorientation can occur in a single site, presents lower barriers for proton transport. 相似文献
30.
Popere BC Della Pelle AM Poe A Thayumanavan S 《Physical chemistry chemical physics : PCCP》2012,14(12):4043-4057
Research in the field of organic photovoltaics has gained considerable momentum in the last two decades owing to the need for developing low-cost and efficient energy harvesting systems. Elegant molecular architectures have been designed, synthesized and employed as active materials for photovoltaic devices thereby leading to a better molecular structure-device property relationship understanding. In this perspective, we outline new macromolecular scaffolds that have been designed within the purview of each of the three fundamental processes involving light harvesting, charge separation and charge transport. 相似文献