A combined surface plasmonic and isotope-selective spectroscopic study toward a deeper understanding of real-time enzymatic urea hydrolysis

We employed the wavelength-interrogated surface plasmon resonance (SPR) method to characterize the real-time kinetics of urea-urease hydrolysis reaction in response to a CO₂-free N₂ environment and CO₂-enriched ambient reaction medium. We established that a simple label-free SPR probe could accurately extract kinetic parameters from the nature of the sharp jump of the SPR wavelength shift in the reaction profile. The kinetic analysis showed that CO₂ production increases with increasing reaction time irrespective of CO₂-free N₂ or CO₂-enriched reaction environment. We also explored the essential insights into the isotopic fractionations of ¹²CO₂, ¹³CO₂, ¹²C¹⁸O¹⁶O in the reaction medium utilizing integrated cavity output spectroscopy. The plasmonic system measured the reaction rate in the order of 10^-7 M/s for urea species in the presence of the urease enzyme. This study deepens our understanding of plasmonic-based enzymatic urea hydrolysis in real time and opens a new way to quantify chemical reaction kinetics for various other systems.

Graphical abstract

This is the first detailed experimental investigation of the real-time kinetics of urea-urease hydrolysis reaction exploiting wavelength-interrogated surface plasmon resonance method in response to produced CO₂ in the CO₂-free N₂ environment and CO₂-enriched ambient reaction medium utilizing integrated cavity output spectroscopy.