%0 Journal Article
%T Performance of the Biocompatible Surfactant Tween 80, for the Formation of Microemulsions Suitable for New Pharmaceutical Processing
%A Cristina Prieto
%A Lourdes Calvo
%J Journal of Applied Chemistry
%D 2013
%R 10.1155/2013/930356
%X The aim of this work was to investigate the phase behaviour and the structure of the n-hexane/water emulsions based on a nonionic, nontoxic and biocompatible surfactant, Tween 80. This system is of interest for new pharmaceutical techniques based on supercritical fluids to form nano- and encapsulated particles. However, it showed a lack of stability denoted by large areas of macroemulsion. For this reason, the effect of additives (alcohols and brine) and external variables (temperature) were explored. The replacement of water by brine caused negligible impact due to the nonionic character of Tween 80. On the contrary, the presence of an alcohol (ethanol or 1-butanol) enhanced the solubility of the surfactant in the oil phase and decreased the mixture viscosity, resulting in improved surface activity. Similar results were obtained by raising the temperature until the cloud point was reached (60ˇăC). With these modifications, microemulsions at relatively low concentrations of surfactant (around 30%) and within a broad interval of compositions could be obtained, widening their possible use in pharmaceuticals manufacturing (such as controlled drug delivery, enzymatic reactions, or excipient processing). The understanding of the surfactant performance could be further used to substitute the n-hexane by a greener solvent, such as supercritical CO2. 1. Introduction Under the principles of sustainable development and being environmentally friendly, a new field, called green chemistry, has been developed based on waste minimisation, energy efficiency, nonhazardous raw materials, solvents or products, inherently safe chemicals processes, and on renewable feedstocks [1]. In this sense, the global pharmaceutical corporations have encouraged the integration of green chemistry and green engineering into the pharmaceutical industry [2]. Between the key research areas for sustainable manufacturing, emulsions have generated a lot of interest, due to the fact that many pharmaceutical processes include direct or indirect contact with some kinds of emulsions in some of their innumerable applications. The term emulsion designates a system composed of two immiscible liquids, one dispersed in the other, in a more or less stable way [3]. It is possible to make these two liquids compatible so that the mixture could be manipulated, administered, and used without breaking. The general structure of emulsions comprises one phase formed by water or a water solution and another phase formed by an organic solvent insoluble in water, which is known as oil. Such emulsions are usually of
%U http://www.hindawi.com/journals/jac/2013/930356/