| Summary: | 碩士 === 國立中正大學 === 化學所 === 98 === Localized plasmon resonance (LPR) is an optical phenomenon generated by excitation with the resonance frequency of an incident light to cause collective oscillations of the conduction electrons near the surface of metal nanoparticles. Typical materials for plasmonic applications are noble metals, especially gold or silver. The frequency and extinction cross-section of the LPR band depends on the size, shape, and dielectric properties of the nanostructure, as well as on the refractive index (RI) of the enviroment. The high sensitivity of the LPR band to local enviroment provides a very sensitive probe to detect small changes in the refractive index (RI) of the surroundings around the nanoparticles, which is particularly attractive for sensing applications.
In this study, we use a gold nanoparticles-modified optical fiber to construct the Fiber-Optic Localized Plasmon Resonance (FO-LPR) Sensor for sensing the refractive index change of the environment due to bio-chemical affinity reactions. By repeated total internal reflection in optic-fiber, it can enhance LPR signal and sensor sensitivity. Results show that the signal changes linearly with the refractive index of a solution and the concentration of a biomolecule. A refractive index sensitivity of 7.08 AU/RIU toward RI change and a limit of detection (LOD) of 1.87×10-8 M for biotin/anti-biotin and a LOD of 2.82×10-10 M for biotin/streptavidin were achieved.
Because the FO-LPR sensor has many advantages such as label-free, real-time, and low cost, it offers a potential to monitor biomarkers of various diseases. This study focuses on the detection of matrix metalloproteinases-3 (MMP-3) and Tumor Necrosis Factor-alpha (TNF-α) in synovial fluid of patients with osteoarthritis (OA). Results showed that the MMP-3 sensor has a LOD of 1.56×10-12 M and the TNF-α sensor has a LOD of 2.19×10-12 M.
Moreover, we also compare the FO-LPR system and ELISA in the determination of the concentration of MMP-3 in patients’ knee. Results by the two methods agree with each other, but FO-LPR can achieve higher sensitivity and lower detection limit for detection of MMP-3 than that by ELISA.
For the purpose of sensing complicate real-sample, like plasma, whole blood, waste water, etc, pre-filtering membrane was integrated with the FO-LPR sensor. Results showed that the refractive index resolution is 3.25 × 10-5 RIU, which is comparable to that with a bare FO-LPR sensor.
Keywords: localized plasmon resonance; gold nanaparticles; Fiber-Optic Localized Plasmon Resonance; osteoarthritis; MMP-3; TNF-α; ELISA
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