Fig. 1. Structure patterns of traditional antibody and nanobody. (a) Traditional antibody IgG. (b) Heavy chain-only antibody in camel. (c) Nanobody.

Fig. 2. (a) Diagrammatic sketch of the STF fabrication. BBS, broadband source; SMF, single-mode fiber; OSA, optical spectrum analyzer. (b) Schematic diagram of the STF interference principle. (c) Microscopic image of the STF.

Fig. 3. Schematic representation of the STF surface modification and the PE detection procedure. The light source emitted from the BBS passes through the STF before reaching the OSA. Subsequently, the output data is imported into the computer for integration.

Fig. 4. Characterization of the STF (a), (b) before and (c), (d) after the introduction of the GO. (e), (f) Characterization of the STF-GO after the introduction of Nb. (g), (h) Characterization of the STF-GO after the introduction of GNP. (i), (j) Characterization of the STF-GO/GNP after the introduction of Nb. (a), (c), (e), (g), and (i) are the SEM images. Correspondingly, (b), (d), (f), (h), and (j) are the EDX spectra.

Fig. 5. Detection of PE. Measured transmission spectra subsequent to the introduction of PE onto the surface of the STF. Through the experimental reaction, the drift of a specific peak was observed and utilized as the response criterion of the sensor to varying concentrations of PE. (a) Sensor with the bilayer film detection results for PE. (b) Sensor with the monolayer film detection results for PE.

Fig. 6. Trend line depicting the correlation between the concentration of PE and the corresponding wavelength shift.

Fig. 7. The histogram of redshifts obtained during the detection of various analytes at a concentration of 20 nm/(ng/mL).