Using optical tweezers combined with video based methods we probe non-specific interactions between polystyrene beads and surfaces at different electrolyte concentrations. We present force-distance relationships and using statiscally based maximum likelihood methods, which significantly improves spatial resolutions, the interaction potentials are also found. At low electrolyte concentrations the interaction potentials are in agreement with DLVO theory, but at high electrolyte concentrations the interaction potentials deviate both from DVLE and Lifshitz theories. Also, we probe the specific interaction between biotin and streptavidin. However, these measurements are complicated because the interaction is of very short range and a streptavidin coated polystyrene bead adheres to a biotin coated surface as soon as it encounters the surface during its Brownian motion in the trap.

Date Published: 18 October 2004
PDF: 8 pages
Proc. SPIE 5514, Optical Trapping and Optical Micromanipulation, (18 October 2004); doi: 10.1117/12.559622

Published in SPIE Proceedings Vol. 5514:
Optical Trapping and Optical Micromanipulation
Kishan Dholakia; Gabriel C. Spalding, Editor(s)