Antibacterial Aqueous Emulsions

An emulsion consists of lipophilic particles dispersed in an aqueous phase and stabilized with a surfactant as shown in Fig. 4.1. The surfactant is a molecule or a polymerized molecule that possesses hydrophilic and lipophilic groups usually at the opposite end of the molecule. The hydrophilic group is soluble in the aqueous phase and stabilizes the particle in the aqueous medium while the lipophilic group is soluble in the lipid or oil phase, that is, in the following cases, lipophilic or hydrophobic. 

Individual materials discussed in patents were tested separately to determine their antibacterial activities along with known control materials such as chlorhexidine derivatives. Attempts were made to compare prior art to any novel developments in the US patents and recently published literature. 

Fatty acids were not discussed in the US patents or literature for the purpose of forming nanoemulsions, but they were included in the study for comparative purposes and because of their low viscosities compared to ester-oils that consist of three fatty acids molecules per oil molecule. The lower viscosity liquids are easier to shear in a homogenizer 

Biocompatible Polymeric Materials and Tourniquets for Wounds, 91 

The following brief literature review of bacteria cellular structure lists just some author s reports from the comprehensive published literature on findings that are pertinent to the present work. 

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Patents have been granted for innovations involving the preparation and activities of broad-spectrum antimicrobial emulsions from 1977 (Sippos) to 2000 (Baker). All of these patents claim antibacterial activity, but all involve additives in the non-aqueous phase of the emulsion that are known to be antibacterial alone and before emulsification. Wide spectrum applications for these nanoemulsions have been claimed with positive results for bacteria, fungi, and viruses. The term nanoemulsion is used in US patents discussed below, but the generic term for the product of an emulsification (Gooch 2002, 1980) of a liquid within a liquid is an emulsion. United States patents 6,015,832 and 5,547,677 were examined and formulations in key claim statements were reproduced, and tested using standard methods for effectiveness. Additional patents listed in the reference section were reviewed as part of this study. 

In some instances, the range and/or spectrum of preservation can be extended by using more than one preservative at a time. Thus a combination of parabens (p-hydroxybenzoic acid) with varying water solubilities may protect both the aqueous and oil phases of an emulsion, while a combination of Germall 115 and parabens results in a preservative system with both antibacterial (Germall 115) and antifungal (parabens) activity. 

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