QCM and SPR study of the enzymatic degradation of cellulose thin films
Two sophisticated surface-sensitive techniques, the quartz crystal microbalance (QCM) and surface plasmon resonance (SPR), were combined to study the interaction of a mixture of cellulolytic enzymes from the fungus 'T. reesei' with two surfaces: polycrystalline gold surfaces, and cellulose thin films deposited on to polycrystalline gold surfaces. We found that the enzyme mixture adsorbed to the gold surface, forming a uniform layer with a thickness of ' t' ~ 13.4 nm, as determined by SPR, that could not be removed by rinsing with buffer solution. The interaction of the enzyme mixture with cellulose thin films was monitored using the QCM. It was found that the QCM results were sensitive to two processes that occur during the enzyme mixture-cellulose thin film experiment: adsorption of the enzyme to the film surface, and the subsequent degradation of the cellulose thin film. A model describing the frequency shift QCM data was introduced, and we found that excellent fits to the experimental data were obtained.