Label-free microfiber biosensor for ultrahigh sensitivity detection of TNF-α protein.

Rapid detection of low concentrations of tumor necrosis factor-α (TNF-α) plays an important role in medical diagnostics. This study proposed a fast, label-free single mode-tapered no core-single mode (STNCS) microfiber structure for the ultra-low concentration of TNF-α detection. The experimental results show that the proposed microfiber biosensors have good spectral stability (0.0316 nm), fast detection (<20 min), good specificity and low limit of detection (LoD). When the STNCS biosensors (functionalized with 20 µg/mL anti-TNF-α antibodies) are immersed in a TNF-α solution at a concentration of 1 pg/mL, the average wavelength shift can reach 0.951 nm, which is close to the theoretical LoD value (1.352 pg/mL). The proposed STNCS microfiber biosensors also demonstrated good specificity, showing limited cross-reactivity to other proteins, including C-reactive protein (CRP), interleukin-6 (IL-6) and bovine serum albumin (BSA). These results indicate that the proposed STNCS biosensors may possess potential uses in medical diagnosis, early detection, and intervention of diseases, etc.