Local and Express Probing of Enzymatic Activity Using Functional Plasmon Active Optical Fiber

Enzymes are very essential part of living organisms and are also actively used by humanity in various technological processes. The activity of enzymes, especially those isolated from microorganisms, can vary significantly from one to another source. Therefore, it is necessary to develop methods for express and the least invasive detection of enzymatic activity. In this work, we propose a biochemical sensor of enzymatic activity created on the basis of a plasmon-active optical fiber probe covalently functionalized with an enzyme-sensitive organic molecules, immersed in the solution, containing (or not) β-glucosidase at various experimental conditions. In the presence of enzyme, the grafted to plasmon-active surface organic moieties undergo cleavage of C-O bond leading to a change in the local environment of the optical fiber probe and to a shift in the spectral position plasmon absorption band, monitored in the back-reflected light. The functionality of the created optical fiber probe was tested at various experimental conditions, including the variation of the external temperature or pH, and results obtained correspond well with results of traditional biochemical tests. It is possible to determine the presence of the enzyme, estimate its concentration, and suppress its activity under unfavourable experimental conditions. The proposed approach allows in site enzyme detection and cheap and express analysis, with minimal disruption of enzymatic systems.