Stabilised controlled release biocide, mechanisms & microbial interaction

The transmission and proliferation of pathogens in liquid systems and on surfaces is a critical issue. This PhD project attempted to gain greater understanding of the issues surrounding biocidal treatments currently employed to address this issue and to develop new chemical formulations to enhance current practice. Formulations were achieved based on silver nanoparticles, with a combination of stabilising agents and surfactants, and their ability to inhibit bacteria investigated. Nanomaterial-based formulations were further prepared with numerous antimicrobial agents, concentration ratios enhanced and evaluated. The emphasis of this research was to find the optimum combination of chemicals and concentrations for sustainable novel antibacterial formulation, with the possibility of numerous applications. Overall, there were ten individually formulated silver nanomaterial samples that were able to exhibit synergistic activity against E. coli (ATCC 25922), or P. aeruginosa, (ATCC 27853). Thirty eight individual non-nanomaterial formulations were developed that were able to exhibit synergism against bacteria, E. coli (ATCC 25922), P. aeruginosa, (ATCC 27853) or S. Aureus (ATCC 25923), when compared with the sum of all components tested individually at corresponding concentrations. An increase in antibacterial activity of 100% was demonstrated for many formulations. There are numerous possibilities for the development of more environmentally sustainable biocidal formulations, in order to eliminate the use of chlorine based biocides. 2