Gold nanoparticle amplified optical microfiber evanescent wave absorption biosensor for cancer biomarker detection in serum.

Sensitive and selective detection for cancer biomarkers is critical in cancer clinical diagnostics. In this work, we report a new optical microfiber (OMF) biosensor using gold nanoparticles (GNPs) as amplification labels for the detection of alpha-fetoprotein (AFP) in serum samples. By combining the unique optical property of OMFs and the strong optical absorption of GNPs, very high sensitivity and selectivity can be achieved. Critical parameters namely fiber diameter and GNP size were optimized for better performance. The limit of detection (LOD) of this sensor for AFP is 0.2 ng/mL in PBS and 2 ng/mL in bovine serum, which is comparable to conventional assays. The advantages of this biosensor are simple detection scheme, fast response time, and ease of miniaturization, which might make this biosensor a promising platform for clinical cancer diagnosis and prognosis.