Publication Details

Knowles, B. R., Yang, D., Wagner, P., MacLaughlin, S., Higgins, M. J. & Molino, P. J. (2019). Zwitterion Functionalized Silica Nanoparticle Coatings: The Effect of Particle Size on Protein, Bacteria, and Fungal Spore Adhesion. Langmuir, 35 (5), 1335-1345.


The negative impacts that arise from biologicalfouling of surfaces have driven the development of coatingswith unique physical and chemical properties that are able toprevent interactions with fouling species. Here, we report onlow-fouling hydrophilic coatings presenting nanoscaledfeatures prepared from different size silica nanoparticles(SiNPs) functionalized with zwitterionic chemistries. Zwitter-ionic sulfobetaine siloxane (SB) was reacted to SiNPs rangingin size from 7 to 75 nm. Particle stability and grafting densitywere confirmed using dynamic light scattering and thermog-ravimetric analysis. Thin coatings of nanoparticles were prepared by spin-coating aqueous particle suspensions. The resultingcoatings were characterized using scanning electron microscopy, atomic force microscopy, and contact angle goniometry. SBfunctionalized particle coatings displayed increased hydrophilicity compared to unmodified particle coating controls whileincreasing particle size correlated with increased coating roughness and increased surface area. Coatings of zwitterated particlesdemonstrated a high degree of nonspecific protein resistance, as measured by quartz crystal microgravimetry. Adsorption ofbovine serum albumin and hydrophobin proteins were reduced by up to 91 and 94%, respectively. Adhesion of bacteria(Escherichia coli) to zwitterion modified particle coatings were also significantly reduced over both short and long-term assays.Maximum reductions of 97% and 94% were achieved over 2 and 24 h assay periods, respectively. For unmodified particlecoatings, protein adsorption and bacterial adhesion were generally reduced with increasing particle size. Adhesion of fungalspores to SB modified SiNP coatings was also reduced, however no clear trends in relation to particle size were demonstrated.

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