Introduction
Quercetin (QU) stands out as the most abundant dietary bioflavonoid supplement, renowned for its
anti-inflammatory, anti-oxidative, and anti-carcinogenic properties. However, the potential for harmful
effects with excessive use necessitates vigilant monitoring. Consequently, continuous screening of
QU assumes paramount importance 1 . Various analytical techniques are employed for QU detection
but simple and rapid approach are needed 1 . Here, we proposed the use of an innovative vapor-phase
polymerization approach to obtain polypyrrole (PPy)-based molecularly imprinted polymers (MIPs) for
QU, within the nanostructure of porous silicon (PSi) photonic crystals, used as interferometers. The
aim is to combine the recognition abilities of the MIP receptors with the optical properties of PSi to
obtain a robust, selective and reusable sensor for QU.
Materials and methods
Porous silicon (PSi) photonic crystals were initially fabricated through an electrochemical etching
procedure on p++ silicon wafers. Subsequently, PSiO 2 layers were obtained via thermal oxidation of
PSi at 1000°C for 10 minutes. In a subsequent step, the QU target was anchored within the PSiO 2
layer, employing an imidazolide-mediated coupling reaction. Afterwards, a vapor-phase
polymerization of Py, developed by our group 2 ,was performed to obtain a thin film around the target.
Successive removal of QU molecules from the polymer matrix produced the imprinted cavities and
then the MIP.
Results and conclusions
The functionalization steps were monitored by UV-VIS spectroscopy, which demonstrated the
effectiveness of the MIP synthesis on PSiO 2 . Preliminary detection tests showed that the sensor can
detect QU in aqueous solutions in a dynamic concentration range between 0.005 to 0.1 mM.
Moreover, the sensor selectivity was tested upon exposure to other antioxidant agents such as gallic
acid and vanillic acid recording in each case a higher sensor response for the target molecule.
Repeatability and stability tests along with QU detection tests in real matrices are in progress.
References
1. doi:10.1080/10408347.2023.2269421.
2. doi:10.1002/SMLL.202302274.