**5. Conclusions**

The proposed platform, based on D-shaped POF and an MIP as the receptor layer, has been demonstrated to be particularly suited for measurements in aqueous matrices since the RI of the layer in contact with the resonant surface (gold) matches the measurable RI range. On the other hand, this strongly depends on the MIP layer's thickness, at least for the MIP here considered.

It has been found that the "wine" matrix has a large effect on the SPR signal since the response of the sensor to 2-FAL is different in water and wine-mimicking solution. The affinity constant is one order of magnitude higher in wine than in water, and consequently, a lower LOD is obtained, reaching interesting values for the determination of 2-FAL in wine.

The method developed for the determination of 2-FAL in wine could have a high practical interest; on the one hand, for the possible toxic and carcinogenic effects of furanic aldehydes, particularly 2-FAL, on human beings and, on the other hand, for their impact on the aroma of food. Interestingly, the sensor here developed could be easily adapted to the analysis of other furanic compounds.

**Author Contributions:** Conceptualization, M.P. and N.C.; methodology, M.P., N.C., L.D.M., L.Z., G.A.; validation, M.P., N.C., L.D.M., L.Z., G.A.; formal analysis, M.P., N.C., L.D.M., L.Z., G.A.; investigation, M.P., N.C., L.D.M., L.Z., G.A.; data curation, M.P., N.C., L.D.M.; writing—original draft preparation, M.P., N.C., L.D.M., L.Z., G.A.; writing—review and editing, M.P., N.C., L.D.M., L.Z., G.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** This work was supported by the VALERE program of the University of Campania Luigi Vanvitelli (Italy).

**Conflicts of Interest:** The authors declare no conflict of interest.
