Single molecule atomic force microscopy and force spectroscopy of chitosan.
Atomic force microscopy (AFM) and AFM-based force spectroscopy was used to study the desorption of individual chitosan polymer chains from substrates with varying chemical composition. AFM images of chitosan adsorbed onto a flat mica substrate show elongated single strands or aggregated bundles. The aggregated state of the polymer is consistent with the high level of flexibility and mobility expected for a highly positively charged polymer strand. Conversely, the visualization of elongated strands indicated the presence of stabilizing interactions with the substrate. Surfaces with varying chemical composition (glass, self-assembled monolayer of mercaptoundecanoic acid/decanethiol and polytetrafluoroethylene (PTFE)) were probed with chitosan modified AFM tips and the corresponding desorption energies, calculated from plateau-like features, were attributed to the desorption of individual polymer strands. Desorption energies of 2.0±0.3×10(-20)J, 1.8±0.3×10(-20)J and 3.5±0.3×10(-20)J were obtained for glass, SAM of mercaptoundecanoic/dodecanethiol and PTFE, respectively. These single molecule level results can be used as a basis for investigating chitosan and chitosan-based materials for biomaterial applications.
Department of Chemistry & Biochemistry, Concordia University, 7141 Sherbrooke Street West, Montréal, Québec, Canada H4B 1R6.
Marta
M
Kocun
Michel
M
Grandbois
Louis A
LA
Cuccia
D000327:Adsorption; D001672:Biocompatible Materials / Q000737:chemistry; D048271:Chitosan / Q000737:chemistry*; D005227:Fatty Acids / Q000737:chemistry*; D005898:Glass; D008422:Materials Testing; D018625:Microscopy, Atomic Force / Q000379:methods*; D008956:Models, Chemical; D011108:Polymers / Q000737:chemistry*; D011138:Polytetrafluoroethylene / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
C505222:11-mercaptoundecanoic acid; D001672:Biocompatible Materials; D005227:Fatty Acids; D011108:Polymers; D013438:Sulfhydryl Compounds; D011138:Polytetrafluoroethylene; D048271:Chitosan