Surfaces that Selectively Manipulate and Kill Bacteria

University Of Massachusetts Amherst, Amherst MA

Investigators

Abstract

ID: MPS/DMR/BMAT(7623) 0805061 PI: Santore, Maria ORG: University of Massachusetts-Amherst Title: Surfaces that Selectively Manipulate and Kill Bacteria INTELLECTUAL MERIT: This program will develop biomaterial surfaces that selectively manipulate bacteria, controlling their adhesion at a level useful for separations, while discriminating and killing targeted types. The surfaces are designed not to harm mammalian cells or accumulate an overcoat of (dead) bacterial debris that can reduce surface activity and support infection. On the surfaces designed and fabricated in this program, the organization of cationic and hydrophobic groups on copolymer chains within antimicrobial polymer brushes will borrow from the membrane-active facially amphiphilic character of host-defense peptides, part of the innate immune system, which evades bacterial resistance. At the 10-300 nm length scale, these new surfaces will emulate the heterogeneous energy landscapes of cell surfaces where rafts cluster proteinaceous functionality to enhance adhesion and signaling. Nano-clustered (10-50 nm) antimicrobial or adhesive functionalities will be randomly distributed on synthetic surfaces whose underlying sterically repulsive character towards cells and bacteria derives from PEG or zwitterionic brushes. These heterogeneous surfaces distinguish bacteria through differences in dynamic adhesion, sensitive to cell size, shape, local curvature, softness (viscoelasticity), and average and local surface chemistry. Besides enabling sensing and separations, the unique dynamic adhesion signatures (skipping, rolling, sliding, arrest) of different bacterial strains and mammalian cells form the basis for their different exposures to antimicrobial functionality, producing selective antimicrobial action, independent of the molecular-scale design. Activities will include synthesis of surface elements and fabrication of surfaces, the experimental study of the dynamic adhesion and viability of bacteria and mammalian cells on these surfaces, the interpretation of data via semiquantitative physico-chemical treatments, and the development of variable-space maps that summarize selectivity, bacterial motion, and viability in a multidimensional materials parameter space. The latter will facilitate rational surface design in diverse applications from implants to clothing. BROADER IMPACTS: The widespread interest in antimicrobial surfaces is driven by the mounting bacterial resistance to antibiotics. Each year in the US there are 90,000 deaths arising from hospital-acquired infections; of these 50,000 are related to catheter infections. So the effective development of antimicrobial polymeric surfaces could have huge practical implications. This project attacks this problem with innovative thinking and technology. The project offers a multidisciplinary setting in which students will be trained in elements of biology, polymer chemistry, materials science, surface science, adhesion, and biophysics. It is proposed that undergraduate students who have worked on the project will be afforded opportunities for industrial intern experience with relevant companies. Outreach to underrepresented groups will be carried out through participation in the Northeast Alliance for Graduate Education and the Professorate, and K-12 outreach will be carried out in conjunction with the UMass MRSEC.