Molecularly Imprinted Polymer (MIP)- Based Optical Sensor for Monitoring Quercetin in Italian Red and White Wines

Sensors was able to detect quercetin within a wide concentration range and linear response was observed in the between 2.5 and 80 M. The sensor proved to be highly selective with very low response towards other antioxidant molecules. Molecularly Imprinted Polymer (MIP)- Based Optical Sensor for Monitoring Quercetin in Italian Red and White Wines T. Di Giulio1, I. M. Asif1, M. Corsi2, S. Rajpal3, B. Mizaikoff3, C. Malitesta1, G. Barillaro2, E. Mazzotta1 1 Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, Università del Salento, Lecce, Italy. 2 Dipartimento di Ingegneria dell'Informazione, Università di Pisa, Pisa, Italy. 3Institute of Analytical and Bioanalytical Chemistry, Ulm University, Germany Abstract Despite enormous research progress and advancements in synthetic methodologies of imprinted polymers, there is still lack of an easy and versatile approach towards molecularly imprinted polymers (MIPs) fabrication on complex nanostructured transducing systems. Here, we explore the application of a very simple and effective room temperature vapor phase polymerization technique to obtain polypyrrole-based MIP film on PSiO2 scaffolds, used as optical transducer. This method allows to develop sensitive, selective and robust sensor for label free detection of quercetin (QU) molecule, that represents one of the most important bioflavonoid in human dietary supplements. The sensor was tested for detection of quercetin in red and white wine samples and the results obtained were in agreement with those recorded by HPLC analysis, highlighting the potential of the sensor to be used in real context for the detection of quercetin in fruits/vegetables derived beverages. Results and Discussions Conclusion The work presents a versatile and simple approach for the synthesis of molecularly imprinted polymers (MIPs) on complex transducing systems. Nanoporous silica was used as transducer for label free detection in a wide concentration range and no significant response were recorded some interfering molecules, such as vanillic acid and gallic acid. The sensor exhibited excellent detection ability for quercetin detection in red and white wine samples showing its potential use for real applications for QU detection in beverages. ▪A red shift in the reflectance spectrum and then an increase in EOT signal was observed after each functionalization step; ▪Only after the target removal from the polymer matrix with the formation of the imprinted cavities (and then of the MIP) a decrease in EOT signal was recorded 0 5 10 15 20 25 30 35 40 45 50 400 500 600 700 800 Reflectance (%) Wavelength (nm) bare PSiO2 APTES functionalization Target (QU) anchoring MIP deposition Target removal PSiO2functionalization and MIP synthesis 0 2 4 6 8 10 12 14 16 18 20 2.5 5.0 10.0 20.0 EOT-EOT0 (nm) [Quercetin] (M) Quercetin Vanillic acid Ferulic acid Gallic acid Caffeic acid y = 0.5746x + 6.3025 R² = 0.992 y = 0.1586x + 1.3794 R² = 0.9663 0 10 20 30 40 50 60 020 40 60 80 100 EOT-EOT0 (nm) [Quercetin] (M) 15 17 19 21 23 25 27 29 31 33 35 0 1 5 10 20 30 60 EOT-EOT0 (nm) Time (days) The MIPs exhibited excellent stability up to 60 days with nearly similar response towards analyte. 0 5 10 15 20 25 30 red wine white wine Concetration foound (M) Real matrix SENSORS RESULTS HPLC RESULTS Quercetin detection in real matrices (red and white wine) were performed and the results are in agreement with those obtained by HPLC analysis Materials and Methods Nanoporous silica (PSiO2) scaffolds were used as an interferometric optical transducers. Preliminary to MIP deposition, QU was anchored to the surface of PSiO2scaffolds by a carbonyl-diimidazole linker, aiming to exploit the advantages of this approach [1]. MIP synthesis by vapor phase polymerization of pyrrole (Py) at room temperature was performed [2]. As control, not imprinted polymers (NIPs) were obtained using the same synthetic approach but without the target during the polymerization. Functionalization steps and analyte binding was monitored by UV-VIS spectroscopy, using the “Effective optical thickness” (EOT) as analytical parameter: EOT = 2 n L (where n = refractive index, L = porous silicon thickness). References [1] E. Mazzotta, T. Di Giulio, C. Malitesta, Anal. Bioanal. Chem. 2022. https://doi.org/10.1007/S00216-022-03981-0. [2] E. Mazzotta, T. Di Giulio, S. Mariani, M. Corsi, C. Malitesta, G. Barillaro, Small 2023, 2302274. https://doi.org/10.1002/SMLL.202302274. This work was partially funded by the European Union Horizon Europe programme under grant agreement No. 101046946 (RESORB). www.resorb-project.eu 0 100 200 300 400 500 600 APTES functionalization Target anchoring PPy synthesis Template removal EOT-EOTPSiO2 (nm) PSiO2 functionalization steps ▪After QU anchoring a sensitive change in reflectance spectrum was recorded due to the absorption of the molecule in the visible light range. Sensor performance (1) ([email protected]). Author profile (scholar) E. Mazzotta Sensor performance (2) Computational studies: insights into target/receptor interaction -1.8 kcal/mol pyrrole quercetin «Polymer level» simulations by molecular dynamics (MD) «Monomer level» simulations by molecular mechanics (MM) docking score: −7.32 MIP synthesis onto PSiO2scaffolds An energetically favourable interaction was computed! PSiO2scaffold used as optical transducers Quercetin detection tests demonstrated good sensitivity within a range from 2.5 a 80 mM. Selectivity tests demonstrated much higher response for target analyte Look at the paper! →