Influence of the Polymer and Solvent Variables on the Nanoencapsulation of the Flavonoid Quercetin: Preliminary Study Based on Eudragit® Polymers

Eudragit® polymers have proven their potential as a means to control the release of aqueous insoluble drugs in various delivery systems as polymer nanoparticles (PNPs). The size (S) and polydispersity index (PDI) of PNPs are crucial factors for their interaction with biological systems from a pharmaceutical standpoint. This study aimed to determine the impact of the volumes of the organic phase (OP) and aqueous phase (AP), as well as the polymer amount (PA), on the size and PDI of PNPs prepared using the nanoprecipitation method for encapsulating quercetin (Qr). The study also evaluated the toxic effects of PNPs on human erythrocytes. The PNPs were prepared using preformed polymers derived from methacrylic acid and polyvinyl alcohol (PVA) as a surfactant. The nanoprecipitation technique enabled the production of particles smaller than 200 nm with a PDI lower than 0.2, and the study established the significant impact (p < 0.05) of the three variables related to the polymers and solvents. The selected PNPs contained 5 mg of Qr and 50 mg of Eudragit polymers (1:10 w/w Eudragit® EPO, E100, L100, and Eudragit L100-55) and diverse concentrations of PVA. The study found that including PVA in the AP increased the Qr encapsulation by up to 98%. The hemolytic potential of Eudragit® PNPs and Qr was assessed in human erythrocytes, with no significant cytotoxic activity observed (p < 0.001) compared with the control. In conclusion, via the nanoprecipitation technique, preparing PNPs with defined and homogeneous S to entrap the flavonol Qr efficiently is possible.