Microemulsions biological applications

Coating of the QDs with suitable materials such as amphiphihc polymer and sihca improves their water dispersabihty and makes them suitable for biological applications. From our research group, water-soluble sihca-overcoated CdS Mn/ZnS highly liuninescent and photostable semiconductor QDs have been prepared using the w/o microemulsion approach [47,184,185]. 

The use of microlatices for biological applications is also very attractive. Let us recall that conventional latices prepared from emulsion polymerization are already used for such purposes, for example, in immunoassays, as adsorbents for proteins, for immobilization of enzymes and antibodies, and for controlled release in drug delivery [165]. The latex particle size is in the range 0.1-10 /im. Stable microlatices in the nanosize range (20-30 nm) may be preferred, and some procedures based on inverse microemulsion polymerization have been proposed for the preparation of nanocapsules [4,166-169]. 

The dynamics of water/AOT/isooctane microemulsions affected by the addition of aromatic heterocyclic compounds (Ar-Ht-C) [44], such as pyridine (Py), 2-aminopyridine (2-Ampy), 3-aminopyridine (3-Ampy), 2-amino-4-methylpyridine (2-Am-4-mpy), and 2-amino-6-methylpyridine (2-Am-6-mpy), reflect a significantly different physiochemical behavior as compared to the organochalcogenide molecules. The chosen compounds represent the relatively small organic molecules, which serve as starting materials to the synthetic Se/Te chemistry [45]. Apart from this, these compounds find wide industrial and biological applications [46]. Organochalcogenides, as depicted above, delay the percolation threshold as compared to the pure microemulsion whereas Ar-Ht-C has been found to favor the... 

As there are other less sophisticated and less expensive techniques available, surfactant-enhanced aquifer remediation will only be useful for decontamination of LNAPL sites in special cases. However, applicable techniques are still needed for DNAPL sites and microemulsion techniques are really promising. Therefore, most research has concentrated on this type of contaminant in recent years. Integrated concepts have been developed including aspects of soil properties [47, 48, 62, 63], density control [47, 48, 62-64], recovery and reuse of microemulsion components [47], biological degradation of residues of contaminants and injected compounds [48, 65] and costs [47, 48, 64, 65]. Two main approaches have been followed for developing effective surfactant systems which form microemulsions with DNAPL, but do not mobilise the liquid contaminant into deeper... 

Currently, two research areas are in full evolution. One concerns the formation of porous materials, keeping in mind the backdrop of various applications, as briefly pointed out in this chapter. Of particular interest is the recent study of Gan et al. [137] showing the possibility of producing materials with a pore size (50-70 nm) on the order of that of the precursor microemulsion. The second very promising domain for which one can envision many forthcoming developments is related to the functionalization of particles. It can be foreseen that the efforts in this field will be mainly directed toward biological and medical applications. 

This class of association colloids can be further divided into several subgroups, which include micelles, vesicles, microemulsions, and bilayer membranes. Each subgroup of association colloids plays an important role in many aspects of colloid and surface science, both as theoretical probes that help us to understand the basic principles of molecular interactions, and in many practical applications of those principles, including biological systems, medicine, detergency, crude-oil recovery, foods, pharmaceuticals, and cosmetics. Before undertaking a discussion of the various types of association colloids, it is important to understand the energetic and structural factors that lead to their formation. 

The search for biodegradable and temperature insensitive microemulsions as various solubilizing and reaction media is of increasing importance for emerging applications in several areas, such as pharmaceutical and medical applications, food products, catalysis, transcriptive syntheses and membrane recognition phenomena, new cosmetic formulations and nanotechnologies. As the medical and pharmaceutical potential of microemulsions needs to be evaluated, the research should be directed not only towards studies of the internal microstructure properties of microemulsions but also at their biological properties such as hemolytic activity and cytotoxicity [1]. 

Another field recently opened is the use of water-in-oil (W/O) microemulsions as reaction media for the synthesis of solid nanoparticles. The interest in synthesizing nanoparticles in solutions of reversed micelles is due to their important technological applications as catalysts for redox reactions [69] or their use to model or mimic processes occurring in geological or biological environments [70],... 

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