Development of a rapid and ultra-sensitive cytosensor: Ω-shaped fiber optic LSPR integrated with suitable AuNPs coverage

Abstract Cytosensor plays a vital role on the cancer diagnosis at early stage. Localized surface plasmon resonance (LSPR)-based fiber optic is a type of emerging cytosensor with the merits of miniaturized devices, real-time and label-free detection, which is, however, limited by its low sensitivity and time-consuming analysis processes. To address those limitations, in this work a one-step LSPR-based cytosensor was constructed featuring Ω-shaped fiber optic with suitable AuNPs coverage. Both refractive index sensitivity (RIS) and density of captured cancer cells increased with a uniform AuNPs, while a sharp decrease of RIS and a plateau of density of captured cancer cells was found when AuNPs coverage increased at aggregation state. Under the same AuNPs coverage, the Ω-shaped fiber optic exhibited an enhanced RIS and efficiency of captured cancer cells, compared to the U-shaped fiber optic, which in hence led to a rapid and ultra-sensitive cytosensor based on Ω-shaped fiber optic cytosensor based on LSPR. The proposed cytosensor with suitable AuNPs coverage has a wide linear range of 5×101 ∼ 1×105 cells/mL with low limit of detection (LOD) of 12 cells/mL for rapid detection of MCF-7 cancer cells just in 37.5 min. Noticeably, an excellent selectivity and anti-inference were achieved by the cytosensor even in fetal bovine serum. Thus, Ω-shaped fiber optic LSPR-based cytosensor has promising application as an analytical method for cancer diagnosis in the further.