Particle assisted removal of microbes from surfaces.

Unlabelled: Increased reliance on kill based approaches for disinfection raises concerns of antimicrobial resistance development and has significantly elevated the need for alternate approaches for skin and substrate disinfection. This study focuses on reducing harmful microbes from substrates primarily via removal and to a lesser extent by kill.

Hypothesis: Functional micro-particles designed to adhere to microbes, with a force greater than the force of microbial adhesion to the substrate, would result in enhanced removal-based disinfection of substrates when subject to an external force.

Experiments: Silica particles were functionalized with a cationic polymer to bind strongly with bacteria via Coulombic interactions. Disinfection efficacies of substrates with functional particles and control groups were evaluated under conditions relevant for handwashing.

Findings: Functionalized silica micro-particles result in ∼4 log reduction of E. coli from an artificial skin substrate in 30 s as compared to a maximum of 1.5 log reduction with control particles. Bacterial viability assays indicate a mechanism of action driven by enhanced removal of bacteria with minimal kill. Particle number density, size and suspension velocity along with strong particle - bacteria interactions have been found to be the primary factors responsible for the enhanced bacterial removal from surfaces.