Zwitterion Functionalized Silica Nanoparticle Coatings: The Effect of Particle Size on Protein, Bacteria, and Fungal Spore Adhesion

Abstract

The negative impacts that arise from biological fouling of surfaces have driven the development of coatings with unique physical and chemical properties that are able to prevent interactions with fouling species. Here, we report on low-fouling hydrophilic coatings presenting nanoscaled features prepared from different size silica nanoparticles (SiNPs) functionalized with zwitterionic chemistries. Zwitterionic sulfobetaine siloxane (SB) was reacted to SiNPs ranging in size from 7 to 75 nm. Particle stability and grafting density were confirmed using dynamic light scattering and thermogravimetric analysis. Thin coatings of nanoparticles were prepared by spin-coating aqueous particle suspensions. The resulting coatings were characterized using scanning electron microscopy, atomic force microscopy, and contact angle goniometry. SB functionalized particle coatings displayed increased hydrophilicity compared to unmodified particle coating controls while increasing particle size correlated with increased coating roughness and increased surface area. Coatings of zwitterated particles demonstrated a high degree of nonspecific protein resistance, as measured by quartz crystal microgravimetry. Adsorption of bovine 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 particle coatings, protein adsorption and bacterial adhesion were generally reduced with increasing particle size. Adhesion of fungal spores to SB modified SiNP coatings was also reduced, however no clear trends in relation to particle size were demonstrated.

Vancomycin-Loaded Nanoparticles Enhance Sporicidal and Antibacterial Efficacy for Clostridium difficile Infection

“…The mechanism by which the van-IONP can possess strong binding affinity to the spores is still not very well understood. It is probably due to the hydrophobic interaction between the exosporium and the nanoparticles (Joshi et al, 2012; Knowles et al, 2018). The van-IONP also showed inhibitory effect on the spore germination in the germination assay.…”

Recent Developments in the Design of Non-Biofouling Coatings for Nanoparticles and Surfaces

“…However, in NPs, the inclusion of charged moieties had a deleterious effect on the non-fouling properties. Therefore, other physical parameters related to shape and size (e.g., curvature or roughness) may play a role when studying planar surfaces versus NPs [63].…”

Biomedical Uses of Sulfobetaine-Based Zwitterionic Materials

“…In a subsequent study, the importance of topography on the antifouling performance of these NP films was shown. 155 Most recently, an additive effect of dual functionalization with SB and quaternary ammonium silane was demonstrated. 156 Quantum dots (QDs) are also useful, as their unique optical and electronic properties allow for imaging-based diagnostics with high and stable signals.…”