Microenvironment, investigation

It is now believed from studies on the natural photosynthetic systems that microenvironments for the photoinduced ET reaction play an important role in the suppression of the back ET [1-3]. As such reaction environments, molecular assembly systems such as micelles [4], liposomes [5], microemulsions [6-8] and colloids [9] have been extensively investigated. In them, the presence of microscopically heterogeneous phases and interfacial electrostatic potential is the key to the ET rate control. 

Morishima et al. [30, 50-54, 73-76] have made extensive investigations on photoinduced ET, using polycyclic aromatic chromophores covalently attached to polyelectrolytes. They were the first to show that the polyeletrolyte molecular surface provides an unusual microenvironment which greatly changes the rate of photoinduced ET and the fate of the charged photoproducts. 

Multiple applications for resilin-like polypeptides have garnered renewed research interest since the report of the first recombinant resilin in 2005. The excellent mechanical properties of the resilin-like polypeptides has directed investigation toward their use as high-performance materials and in tissue engineering applications. It is widely acknowledged that cells interact and take cues from their microenvironment and, therefore, the development of polymeric scaffolds to mimic the extracellular matrix and drive desired cell or tissue responses has been of wide interest. To this end, our laboratories have developed a modular resilin-like polypeptide (RLP12) (see Fig. 20) that contains not only twelve repeats of the... 

Porphyrin complexes are particularly suitable cores to construct dendrimers and to investigate how the behavior of an electroactive species is modified when surrounded by dendritic branches. In particular, dendritic porphyrins can be regarded as models for electron-transfer proteins like cytochrome c [42, 43]. Electrochemical investigation on Zn-porphyrins bearing polyether-amide branches has shown that the first reduction and oxidation processes are affected by the electron-rich microenvironment created by the dendritic branches [42]. Furthermore, for the third generation compound all the observed processes become irreversible. 

Although most often connected with investigations of solid dosage forms, diffuse reflectance spectroscopy can also be used to characterize alternative formulations. Through the use of a special sample cell, the technique has been used to study the stability of emulsions [37]. In this work, it was found that information could be obtained that pointed toward subtle changes in the emulsion microenvironment. 

The evidence accumulated in the literature suggests that the structure of surfactant adsorbed layers is, in some respects, analogous to that of surfactant micelles. Fluorescence probing techniques - e.g., pyrene and dinaphtylpropane (DNP) fluorescence probes are used to investigate the structure of adsorbed layer of a surfactant - give information on the polarity of the microenvironment in the adsorbed... 

Fluorescence is also a powerful tool for investigating the structure and dynamics of matter or living systems at a molecular or supramolecular level. Polymers, solutions of surfactants, solid surfaces, biological membranes, proteins, nucleic acids and living cells are well-known examples of systems in which estimates of local parameters such as polarity, fluidity, order, molecular mobility and electrical potential is possible by means of fluorescent molecules playing the role of probes. The latter can be intrinsic or introduced on purpose. The high sensitivity of fluo-rimetric methods in conjunction with the specificity of the response of probes to their microenvironment contribute towards the success of this approach. Another factor is the ability of probes to provide information on dynamics of fast phenomena and/or the structural parameters of the system under study. 

Having an increased or elevated reactivity. This term has been used in reference to the relative activity of amino acyl residues at the active sites of enzyme. The immediate environment (Le., the microenvironment) may allow simple reagents to react faster with the amino acid than would normally be expected. Thus, in labeling of proteins with active site-directed reagents, an investigator should always consider the basis of increased reactivity Is it due to facilitation of the reaction by increased affinity (Le., affinity labeling), or is it due to increased activity of the amino acyl side chain (e.g., perhaps increased nucleophilicity due to the microenvironment). 

The success of cellular therapies ultimately depends on the stability of the hepatocyte in the architecture in which it must exist. Primary hepatocytes are anchorage dependent. Isolated cells rapidly lose viability when cultured in monolayers or suspensions. Investigators have developed culture models based on features of liver architecture to recapitulate the complex hepatocyte microenvironment. Sandwich culture mimics the environment of hepatocytes in vivo by entrapping cells between two layers of collagen gel. However, such methods introduce additional transport barriers and are difficult to scale up to therapeutic levels. ... 

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