Introducing Porosity in Colloidal Biocoatings for Functional Biocatalysis - poster

Yuxiu Chen¹*, Simone Krings², Joshua R. Booth³, Stefan A. F. Bon³, Suzanne Hingley-Wilson², Joseph L. Keddie¹*
¹ Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, UK
² Department of Microbial Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK
³ Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK

A biocoating is a recently-developed material that employs a colloidal polymer (latex) film to confine non-growing, metabolically-active bacteria. Bacteria encapsulated inside biocoatings are intended to be used as a biocatalyst in applications including remediation of pollutants and production of useful by-product. A biocoating needs to have high permeability to allow a high rate of mass transfer for rehydration and the transport of both nutrients and metabolic products. It therefore needs an interconnected porous structure. Here, we exploited rigid tubular nanoclays (halloysite) and non-toxic latex particles with a relatively high glass transition temperature as colloidal building blocks to tailor porosity inside biocoatings. SEM images revealed inefficient packing of the rigid nanotubes and proved the existence of nanovoids along the halloysite/polymer interfaces. A custom-built apparatus was used to measure the permeability of a fluorescein sodium salt in the biocoatings. Whereas there was no measurable permeability in a polymer film made from only latex particles, the composites with an increased halloysite content had an increasing permeability coefficient (up to 1´10^-4 m h^-1). As a result, bacteria encapsulated in halloysite composite biocoatings had statistically significant higher metabolic activities in comparison to bacteria encapsulated in a non-optimized coating made from latex particles alone.