Synthesis and characterization of poly (N-isopropylacrylamide)-g-carboxymethyl chitosan copolymer-based doxorubicin-loaded polymeric nanoparticles for thermoresponsive drug release

Thermoresponsive graft copolymer (PNIPAm-g-OCMC) with PNIPAm and chitosan was prepared by conjugation of amine-terminated PNIPAm with O-carboxymethylchitosan through graft-onto method. The results of FTIR and proton NMR confirmed the synthesis of a copolymer. Furthermore, XRD analysis revealed conjugation reaction of polymeric materials. Doxorubicin-loaded polymeric nanoparticles (D-PNPs) were fabricated using copolymer by gelation method. Morphology illustration through TEM showed the spherical shape of D-PNPs. Particles size measurement study indicates thermoresponsive properties of D-PNPs at various temperatures. Lower critical solution temperature (LCST) of D-PNPs was obtained at 38 °C predicted by turbidimetry analysis. Release studies at three different temperatures notified that thermoresponsive doxorubicin release of D-PNPs. The release of doxorubicin was slower at 25 °C, moderately released at 37 °C, and faster released at 42 °C due to adjustment of the framework of the D-PNPs. Based on the results such as transmittance measurement, particle size observation, and release studies, we declare that the D-PNPs exhibit temperature-responsive behavior, which could make them appropriate for a thermoresponsive drug delivery.