(161af) Highly Sustained Release of Bactericides from Polyelectrolyte/Multivalent Ion Coacervates

To address challenges with the delivery, toxicity and repeated application of antibacterial agents, there has been substantial interest in technologies for their long-term controlled release. Recently, our lab has shown that complex coacervates prepared through poly(allylamine hydrochloride) (PAH) complexation with the pentavalent anion, tripolyphosphate (TPP) enable the highly sustained (multi-month) release of active small molecules. Building on this work, here we report the use of PAH/TPP coacervates in the encapsulation and long-term release of the model hydrophobic biocide, triclosan (TC), which was dispersed in the coacervate with the aid of a nonionic surfactant. The bactericide content within these coacervates was easily and predictably tuned by varying the TC amounts dispersed in the parent PAH solutions. The TC was then slowly released from the coacervates into regularly replaced tap water, over timescales that exceeded 100 days, and at rates that could be readily tailored by adjusting the encapsulated TC and surfactant content. To explore the efficacy of this sustained-release system in long-term disinfection, gram-positive (S. aureus) and gram-negative (E. coli) bacteria were used as model pathogens. Fluorescence microscopy and turbidimetric analyses confirmed that, despite decreasing with time (likely due to gradual reductions in TC release rates), bactericidal activity achieved with these coacervates persisted for over a month. These findings suggest that bactericide-eluting PAH/TPP coacervates could be used for sustained disinfection. Finally, a possible approach for reaccelerating release from these coacervates (once it becomes too slow to be effective) will also be briefly discussed.