In direct detection assays, AuNPs are chemically bound to the unclad optical fiber surface. Receptor ligands are subsequently functionalized to the AuNPs. During detection, target analytes bind directly to the receptor ligands. Formation of analyte-receptor complexes induces a local change of refractive index near the sensing surface, producing an optical response proportional to the mass concentration of the bound target analytes.
Target: tumor necrosis factor-α (TNF-α) in synovial fluid
Tumor necrosis factor-α (TNF-α) is a proinflammatory cytokine that can act as a biomarker for the early detection of osteoarthritis (OA), the chronic and systematic inflammation of the joints that can be found in synovial joints of the body.
Target: matrix metalloproteinases-3 (MMP-3) in synovial fluid
Matrix metalloproteinases-3 (MMP-3) is an enzyme induced by inflammatory cytokines such as TNF-α and interleukin-1β that also indicates OA.