Fiber optic surface plasmon resonance based lactate sensor using co-immobilization of lactate dehydrogenase and NAD+

Abstract

Abstract An efficient, simple and sensitive surface plasmon resonance based optical fiber sensor for the detection of lactate in the concentration range 0–10 mM is reported. For the fabrication of sensing probe, layers of silver and silicon are grown over an unclad portion of an optical fiber acting as a substrate followed by co-immobilization of enzyme and co-enzyme in a hydrogel layer. The sensor is operated in the spectral mode of interrogation, with resonance wavelength found to be increasing with increasing lactate concentration. A shift of 31 nm in resonance wavelength is observed for the lactate concentration range 0 mM–10 mM. The limit of detection and the sensitivity of the sensor are found to be 0.24 mM and 9.50 nm/mM, respectively. The fabricated sensor is stable, selective and has good repeatability. Furthermore, the sensor offers added advantages like reduced cost, simple operation and fast response. Being developed on an optical fiber, the sensor offers unique advantages of online monitoring and remote sensing of lactate without being interfered by stray electromagnetic fields.