Microgel particles are being applied to a variety of nano- and microtechnologies such as biomaterials, materials for enhancing oil refinery, and catalysis. Highly deformable microgel particles dispersed in solvent, swell more than stiffer particles because the latter have a higher crosslinking density. However, when these microgel particles are crosslinked to a surface, particle confinement will play a role in the microgel particle swelling behavior and surface adhesion. In this project we analyze the surface adhesion of thermo-responsive microgel particles, which had been immobilized to a surface, as a function of particle deformability. The microgel particles were poly n-isopropylacrylamide (NIPAM) particles, synthesized via precipitation polymerization. The NIPAM microgels were crosslinked to glass substrates via ECD/sulfo-NHS crosslinking chemistry. They were then surface-functionalized with heat-treated BSA (negative control) and biotinylated-BSA (positive control). In order to examine the impact particle stiffness had on surface chemistry, surface adhesion was measured, using atomic force microscopy (AFM). The surface adhesion was measured between both BSA- and biotinylated-BSA- functionalized microgel particles, with surface-functionalized modified AFM tips (BSA- and streptavidin- functionalized tips, respectively). The BSA-functionalized surfaces were used as negative controls, and showed no evidence of adhesion, irrespective to particle stiffness.
