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Combined QCM-D/GE as a tool to characterize stimuli-responsive swelling of and protein adsorption on polymer brushes grafted onto 3D-nanostructures

Year: 2014

Journal: ANALYTICAL AND BIOANALYTICAL CHEMISTRY, November 2014, Volume 406, Issue 28, pp 7233-7242, 20150429

Authors: Koenig, Meike; Kasputis, Tadas; Schmidt, Daniel; Rodenhausen, Keith B.; Eichhorn, Klaus-Jochen; Pannier, Angela K.; Schubert, Mathias; Stamm, Manfred; Uhlmann, Petra

Organizations: Leibniz Inst Polymerforsch Dresden eV, D-01069 Dresden, Germany; Tech Univ Dresden, Dept Phys Chem Polymer Mat, D-01062 Dresden, Germany; Univ Nebraska, Dept Biol Syst Engn, Lincoln, NE 68588 USA; Univ Nebraska, Dept Elect Engn, Lincoln, NE 68588 USA; Univ Nebraska, Dept Chem & Biomol Engn, Lincoln, NE 68588 USA; Univ Nebraska, Ctr Nanohybrid Funct Mat, Lincoln, NE 68588 USA; Univ Nebraska, Nebraska Ctr Mat & Nanosci, Lincoln, NE 68588 USA

A combined setup of quartz crystal microbalance and generalized ellipsometry can be used to comprehensively investigate complex functional coatings comprising stimuli-responsive polymer brushes and 3D nanostructures in a dynamic, noninvasive in situ measurement. While the quartz crystal microbalance detects the overall change in areal mass, for instance, during a swelling or adsorption process, the generalized ellipsometry data can be evaluated in terms of a layered model to distinguish between processes occurring within the intercolumnar space or on top of the anisotropic nanocolumns. Silicon films with anisotropic nanocolumnar morphology were prepared by the glancing angle deposition technique and further functionalized by grafting of poly-(acrylic acid) or poly-(N- isopropylacrylamide) chains. Investigations of the thermoresponsive swelling of the poly-(N-isopropylacrylamide) brush on the Si nanocolumns proved the successful preparation of a stimuli-responsive coating. Furthermore, the potential of these novel coatings in the field of biotechnology was explored by investigation of the adsorption of the model protein bovine serum albumin. Adsorption, retention, and desorption triggered by a change in the pH value is observed using poly-(acrylic acid) functionalized nanostructures, although generalized ellipsometry data revealed that this process occurs only on top of the nanostructures. Poly-(N-isopropylacrylamide) is found to render the nanostructures non-fouling properties.