DIRECT MEASUREMENT OF PARTICLE BINDING TO CONTROLLED AND ENVIRONMENTAL MATERIALS
Matthew Rush1, Scott Speckart2, Sara Brambilla2, Michael Brown2, Gabriel Montano1.
Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 2Los Alamos National Laboratory, Los Alamos, NM.
Intermolecular forces between small colloidal particles (< 100 µm) and solid surfaces are a fundamental phenomenon of interfacial science. However, given their relatively weak attractive forces (10 – 100 nN) and short interaction distance (< 100 nm), adhesion of small particles can be difficult to measure. In order to develop more robust particle dispersion models, this work investigates how natural/biological materials interact with environmental substrates. Through this research, we have established improved methods of colloid probe fabrication allowing for the interrogation of surfaces in a consistent manner using atomic force microscopy. Results indicate that adhesion between smooth particles and surfaces increases linearly with particle diameter, but can vary substantially between materials. Furthermore, surface roughness caused by debris deposition introduces asperities (0.5 nm – 500 nm) that can reduce or prevent adhesion. A comparison between ideal surfaces (free of small particles and organic materials) and environmental substrates (left outside for 6 weeks) revealed the preservation of strong attractive forces in clean regions while resulting in a loss of adhesion in fouled areas. This work has implications in particle physics, cell-surface interactions, and anti-fouling materials through the ability to directly measure particle surface interactions while simultaneously observing the binding environment. Upon further development, we can begin to understand and control particle/cellular-binding environments through a more complete understanding of nanoscale interactions.