Monitoring enzyme kinetic behavior of enzyme-quantum dot bioconjugates

摘要

Luminescent semiconductor nanocrystals or quantum dots (QDs) hold tremendous promise for in vivo biosensing, cellular imaging, theranostics, and smart molecular sensing probes due to their small size and favorable photonic properties such as resistance to photobleaching, size-tunable PL, and large effective Stokes shifts. Herein, we demonstrate how QD-based bioconjugates can be used to enhance enzyme kinetics. Enzyme-substrate kinetics are analyzed for solutions containing both alkaline phosphatase enzymes and QDs with enzyme-to-QD molar ratios of 2, 12, and 24 as well as for a solution containing the same concentration of enzymes but without QDs. The enzyme kinetic paramters V_(max), K_M, and K_(cat)/K_M are extracted from the enzyme progress curves via the Lineweaver-Burk plot. Results demonstrate an approximate increase in enzyme efficiency of 5 - 8% for enzymes immobilized on the QD versus free in solution without QD immobilization.