COLL 394 |
| Ijeoma M Nnebe and James W Schneider. Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 |
| Tapping-mode (TM) AFM in liquids is firmly established as a means of high-resolution imaging of soft surfaces. In this work, we investigate the utility of TM as a force measurement tool. We show that quantitative extraction of tip-sample interactions is attainable using a forced damped harmonic oscillator model with distance-dependent dissipation to describe the cantilever dynamics. We provide results from the measurement of: (i) steric forces from grafted poly(ethylene) glycol (PEG) chains; (ii) PEG bridging attraction; (iii) and streptavidin-biotin adhesion. We show that the measured magnitude of steric forces from PEG chains is equivalent to that measured in SFA. However, in studies of the bridging of PEG chains and streptavidin-biotin adhesion, we observe that the magnitude of the measured forces is comparable to dc force measurements. Our results illustrate the potential of TM in liquid for the less-destructive and more sensitive measurement of interactions on biomaterials and polymer-coated surfaces. |
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Nanoscience and Nanotechnology
8:30 AM-11:45 AM, Wednesday, March 31, 2004 Marriott -- Orange County 5, Oral
Division of Colloid and Surface Chemistry |