Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Mar 10;22(6):2141.
doi: 10.3390/s22062141.

Relevance of the Spectral Analysis Method of Tilted Fiber Bragg Grating-Based Biosensors: A Case-Study for Heart Failure Monitoring

Miguel Vidal  1 , Maria Simone Soares  1 , Médéric Loyez  2 , Florinda M Costa  1 , Christophe Caucheteur  2 , Carlos Marques  1 , Sónia O Pereira  1 , Cátia Leitão  1
Affiliations

Relevance of the Spectral Analysis Method of Tilted Fiber Bragg Grating-Based Biosensors: A Case-Study for Heart Failure Monitoring

Miguel Vidal et al. Sensors (Basel). .

Abstract

Optical fiber technology has rapidly progressed over the years, providing valuable benefits for biosensing purposes such as sensor miniaturization and the possibility for remote and real-time monitoring. In particular, tilted fiber Bragg gratings (TFBGs) are extremely sensitive to refractive index variations taking place on their surface. The present work comprises a case-study on the impact of different methods of analysis applied to decode spectral variations of bare and plasmonic TFBGs during the detection of N-terminal B-type natriuretic peptide (NT-proBNP), a heart failure biomarker, namely by following the most sensitive mode, peaks of the spectral envelopes, and the envelopes' crossing point and area. Tracking the lower envelope resulted in the lowest limits of detection (LOD) for bare and plasmonic TFBGs, namely, 0.75 ng/mL and 0.19 ng/mL, respectively. This work demonstrates the importance of the analysis method on the outcome results, which is crucial to attain the most reliable and sensitive method with lower LOD sensors. Furthermore, it makes the scientific community aware to take careful attention when comparing the performance of different biosensors in which different analysis methods were used.

Keywords: NT-proBNP; biosensors; cardiac biomarker; optical fiber sensors; spectral demodulation methods; surface plasmon resonance (SPR).

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Sketch of the biofunctionalization steps for the bare TFBG.
Figure 2
Figure 2
Sketch of the biofunctionalization steps for the Au–TFBG.
Figure 3
Figure 3
Experimental setup using TFBG sensors (image not to scale).
Figure 4
Figure 4
Transmitted spectra denoting the upper and lower envelopes used for the respective methods of analysis for (a) the bare TFBG and (b) the Au–TFBG.
Figure 5
Figure 5
(a) Spectral evolution of the biofunctionalized bare TFBG, in PBS, before (0 ng/mL) and after incubation in each concentration of NT-proBNP (0.01–1000 ng/mL), zooming in on the most sensitive mode around 1531 nm; (b) Wavelength (top) and absolute amplitude (bottom) variations with concentration, showing the Langmuir–Freundlich fit to the experimental data.
Figure 6
Figure 6
(a) Evolution of the lower envelope minimum from the biofunctionalized bare TFBG, recorded after each NT-proBNP concentration; (b) Respective wavelength shifts of the lower envelope, evidencing the Langmuir–Freundlich fit.
Figure 7
Figure 7
(a) Spectral evolution of the biofunctionalized Au–TFBG, recorded in PBS, before (0 ng/mL) and after incubation in each concentration of NT-proBNP (0.01–1000 ng/mL), zooming in on the SPR mode (top inset) and the most sensitive mode around 1544 nm (bottom inset); (b) wavelength and (c) absolute amplitude shifts as a function of concentration, with the Langmuir–Freundlich fitting to the data.
Figure 8
Figure 8
(a) Evolution of the spectra and respective envelopes from the biofunctionalized Au–TFBG in response to increasing NT-proBNP concentration, where the shaded area indicates the SPR signature; (b) Progression of the lower envelope maximum and upper envelope minimum; Plot of the wavelength shift of (c) lower and (d) upper envelopes, showing the Langmuir–Freundlich fitting.
Figure 9
Figure 9
(a) Crossing point and (b) area variations as a function of NT-proBNP concentration, with the respective Langmuir–Freundlich fittings.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

References

    1. Chen C., Wang J. Optical biosensors: An exhaustive and comprehensive review. Analyst. 2020;145:1605–1628. doi: 10.1039/C9AN01998G. - DOI - PubMed
    1. Soares M.S., Vidal M., Santos N.F., Costa F.M., Marques C., Pereira S.O., Leitão C. Immunosensing Based on Optical Fiber Technology: Recent Advances. Biosensors. 2021;11:305. doi: 10.3390/bios11090305. - DOI - PMC - PubMed
    1. Soler M., Lechuga L.M. Principles, technologies, and applications of plasmonic biosensors. J. Appl. Phys. 2021;129:111102. doi: 10.1063/5.0042811. - DOI
    1. Loyez M., Lobry M., Wattiez R., Caucheteur C. Optical Fiber Gratings Immunoassays. Sensors. 2019;19:2595. doi: 10.3390/s19112595. - DOI - PMC - PubMed
    1. Leitão C., Pereira S.O., Alberto N., Lobry M., Loyez M., Florinda M., Pinto J.L., Caucheteur C., Marques C. Cortisol in-fiber ultrasensitive plasmonic immunosensing. IEEE Sens. J. 2021;21:3028–3034. doi: 10.1109/JSEN.2020.3025456. - DOI