Novel carbon quantum dots incorporated polyacrylic acid/polyethylene glycol pH-sensitive nanoplatform for drug delivery

Quercetin (Qc) is a safe plant metabolite that plays an effective role as a chemical inhibitor against tumor cells and in preventing the progression of many cancers. In this research, carbon quantum dots (CQDs) dispersed in a pH-sensitive hydrogel comprising polyacrylic acid (PAA) and polyethylene glycol (PEG) were prepared with the aim to enhance the effectiveness and bioavailability of Qc drug. The PAA-PEG-CQDs-Qc nanoplatform was synthesized using the double emulsion method in order to control its size and shape. Numerous tests have been carried out to characterize the novel nanocarrier including FTIR, XRD, FE-SEM, DLS, and zeta potential, which corroborated its successful synthesis as well as its stability in a physiological environment. Very high drug loading and encapsulation efficiencies (47% and 89%, respectively) were attained, ascribed to hydrogen bonding of Qc with PAA and PEG as well as π-π interactions with the CQDs. Further, a sustained and selective drug release in acidic conditions similar to the tumor site was found. MTT and flow cytometry were used to assess the cytotoxicity of PAA, PAA-PEG, PAA-PEG-CQDs and PAA-PEG-CQD-Qc on the MCF-7 cancer cell line. Experimental results revealed that the drug-loaded nanocarrier had considerably higher cytotoxicity than the free drug, as well as increased apoptotic cell death, due to a synergistic effect of all the nanocomposite components in preventing the survival of cancer cells.