Tuning the pH-sensitive cationic nanopolymers for in vitro release of doxorubicin

In the present study, Chitosan (CS) along with N-isopropyl acrylamide (NIPAAM) and 2-(Di isopropyl amino) ethyl methacrylate (DPA), were used to synthesize polymeric nanoparticles (PNPs) for delivering Doxorubicin (DOX) (having anti-cancer effects) at the malignant site. In the FTIR spectrum, peaks of OH at 3411 cm⁻¹, N-H at 1534 cm⁻¹, and C=O at 1630 cm⁻¹ confirmed the presence of constituent molecules in the PNPs while appearance of no peak between 3000 to 3100 cm⁻¹ depicted successful free radical polymerization through cleavage of double bond. The semi-circular appearance with 251 nm average particle size was confirmed through SEM analysis. The thermal stability was quantified by TGA i.e., no considerable degradation up to 97 °C. The amorphous nature was determined by the XRD pattern of PNPs at 2ϴ. The MTT assay of DOX-loaded PNPs showed 88.5% cell inhibition. At an acidic pH of 5.3, a maximum of 243% swelling was achieved in 80 hours as compared to 140% and 73% swelling at pH 6.5 and pH 7.4 respectively. The DOX loading was found to be maximum at 85.6% (4.28 mg/5 mg) of the drug feed in solution. There was a more prominent 81% (3.46 mg/4.28) DOX release at the internal pH of tumor cells i.e., 5.3.