Controlled-release systems for biocidal chemicals are being explored to overcome challenges with biocide toxicity, repeated application, and shelf life. Recently, our lab has shown that encapsulation of small hydrophilic molecules within putty-like complex coacervates that form upon poly(allylamine hydrochloride) (PAH) complexation with sodium tripolyphosphate (TPP) enables their sustained release over multiple months. Building on this work, here we report encapsulation and long-term release of a model hydrophobic biocide, triclosan (TC), which may be used for sustained inhibition of bacterial growth in confined areas with running or stagnant water (e.g., in bathrooms and kitchens). Nonionic surfactant, Tween 20 (TW), was used to disperse TC in PAH solution, whereupon TPP was added to generate macroscopic PAH/TPP coacervates that efficiently encapsulated the TC. The biocide content within these coacervates was readily tuned by modifying the TC amounts dispersed in the parent PAH solutions. The TC could then be slowly released from the coacervates into (regularly replaced) tap water, over timescales that exceeded 100 days. To test the efficacy of this sustained-release system in long-term disinfection, gram-positive (<i>S. aureus</i>; ATCC 25923) and gram-negative (<i>E. coli</i>; ATCC 25922) bacterial strains were used as model pathogens. Fluorescence microscopy and turbidimetric analyses confirmed (at least partial) killing of bacterial cells for over 1 month, which suggests that biocide-loaded PAH/TPP coacervates could be used for sustained disinfection in household, hospital and institutional settings.

Complex coacervates for long-term release of disinfectants

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

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