Conjugation of antioxidant molecule to PEGylated NPs for pH dependent drug release

Highlights: • Synthesis of Quercetin loaded PEGylated CdSe and PEGylated CdSe/CdS core/shell nanoparticles. • Quercetin quenches the fluorescence intensity of PEGylated nanoparticles. • Conjugation of Quercetin does not alter the spherical morphology of PEGylated nanoparticles. • Effect of pH environment on the optical properties of Quercetin loaded PEGylated nanoparticles. • In vitro release of Quercetin from PEGylated nanoparticles is pH and time dependent. - Abstract: This paper reports the encapsulation of antioxidant molecule Quercetin on PEG-diamine coated nanoparticles (NPs) by aqueous synthesis method to improve it's poor water solubility and stability. Two types of PEGylated NPs (PEGylated CdSe and PEGylated CdSe/CdS) have been used to conjugate Quercetin. The synthesis have been done using two different approaches, in first case organic solvent DMSO along with DI (De-Ionized) water have been used to dissolve Quercetin whereas during the second procedure DI water have been solely used to dissolve Quercetin. UV–vis absorption spectroscopy, TEM and IR results give the confirmation of conjugation of Quercetin to PEGylated NPs. Controlled release has been observed for both pH environments with a maximum release for CPD-I with 95.89% at pH 7.4 whereas at pH 5 CCPD-I shows maximum release i.e. 76.10%. The antioxidant activity results provide that the Quercetin molecules retain their antioxidant properties after conjugation with PEGylated NPs.