Optimizing the Mass-Specific Activity of Bilirubin Oxidase Adlayers through Combined Electrochemical Quartz Crystal Microbalance and Dual Polarization Interferometry Analyses

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• 作者：Trevor McArdle ; Thomas P. McNamara ; Fan Fei ; Kulveer Singh ; Christopher F. Blanford
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：November 18, 2015
• 年：2015
• 卷：7
• 期：45
• 页码：25270-25280
• 全文大小：631K
• ISSN：1944-8252

文摘

Two surface analysis techniques, dual polarization interferometry (DPI) and analysis by an electrochemical quartz crystal microbalance with dissipation capability (E-QCM-D), were paired to find the deposition conditions that give the highest and most stable electrocatalytic activity per adsorbed mass of enzyme. Layers were formed by adsorption from buffered solutions of bilirubin oxidase from Myrothecium verrucaria at pH 6.0 to planar surfaces, under high enzyme loading (鈮? mg mL^鈥?) for contact periods of up to 2 min. Both unmodified and carboxylate-functionalized gold-coated sensors showed that a deposition solution concentration of 10鈥?5 mg mL^鈥? gave the highest activity per mass of adsorbed enzyme with an effective catalytic rate constant (k_cat) of about 60 s^鈥?. The densification of adsorbed layers observed by DPI correlated with reduced bioactivity observed by parallel E-QCM-D measurements. Postadsorption changes in thickness and density observed by DPI were incorporated into Kelvin鈥揤oigt models of the QCM-D response. The modeled response matched experimental observations when the adlayer viscosity tripled after adsorption.