Fiber-Optic SPR Biosensor With BOD/AuNPs Co-Modification for Bilirubin Detection

A Fiber-optic surface plasmon resonance (SPR) bilirubin biosensor based on gold nanoparticles (AuNPs) and bilirubin oxidase (BOD) was proposed in this work. Leveraging the refractive index (RI) sensitivity of SPR and the specific binding capability of BOD to bilirubin, this sensor enables specific detection of bilirubin. To improve the sensitivity of bilirubin detection, AuNPs were introduced to amplify the evanescent field for optical signal enhancement while providing a high surface area for increased BOD immobilization sites. Experimental results demonstrated that the sensor achieved a sensitivity of 54.6 nm/mM within the 0–0.14 mM concentration range and a detection limit of $11.5~\mu $ M. This sensor exhibits the advantages of low sample consumption, compact size, rapid response, good stability, and high specificity. Additionally, the accurate detection of bilirubin in real serum samples demonstrates its great application potential for clinical diagnosis.