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14 November 2002 Interactions of poly(amino acids) in aqueous solution with charged model surfaces- analysis by colloidal probe
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Biomolecules in a confined solution environment may be subject to electrostatic forces with a range up to 100 nm, while the van der Waals interaction will account for shorter-range forces. The response of two model poly(amino acids) - poly-L-lysine and poly-L-glutamic acid - has been investigated for a number of model surfaces at pH 6 - including silica/Si-oxide. The model amino acids were adsorbed, or covalently coupled, to colloidal probes consisting of a microsphere attached to a force-sensing lever. The methodology was based on sensing of an interaction between the probe and a flat surface through carrying out force versus distance analysis with an atomic force microscope. The results were analysed within the framework of the conventional DLVO theory. The outcomes illustrate both repulsive and attractive long-range interactions that will hinder, or promote, colloidal biospecies in solution from entering the region of short-range force-fields at the physical interface. Accordingly the results have implications for the efficacy of methods and devices that seek to exploit the properties of micro/nano-fluidic systems. Large 'snap-on' distances were observed for some systems and were ascribed to compression of the 'soft' functionalized layers. Those observations and measurements of adhesion provided insights into conformation of the adsorbed species and strength of attachment.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Gregory S. Watson, Jolanta A. Blach, Colm Cahill, Dan V. Nicolau, Duy K. Pham, Jonathan P. Wright, and Sverre Myhra "Interactions of poly(amino acids) in aqueous solution with charged model surfaces- analysis by colloidal probe", Proc. SPIE 4937, Biomedical Applications of Micro- and Nanoengineering, (14 November 2002);

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