Surface plasmon optical detection of β-lactamase binding to different interfacial matrices combined with fiber optic absorbance spectroscopy for enzymatic activity assays

In this study, we describe the attachment of biotin-functionalized β-lactamase to different types of interfacial architectures. Generic biotin-NeutrAvidin binding matrices were assembled using biotin-terminated alkanethiol and poly (L-lysine)-g-poly (ethylene glycol) polymer. Quantitative comparisons were made between different matrices and binding strategies. In addition, the feasibility of regeneration was tested. Our results show that in general all matrices were well suited for the binding of the protein, although quantitative differences were observed and will be discussed. Furthermore, the results obtained by surface plasmon resonance spectrometer and optical waveguide measurements show excellent correlation. For all five matrices investigated, real time enzymatic activity assays of β-lactamase were performed by a detection scheme that combines an affinity and a catalytic sensor. The results show that the surface-immobilized enzymes are stable and sufficiently active for highly sensitive catalytic activity measurements. The effect of surface immobilization on the catalytic activity of the enzyme is discussed.