Development of magnetic and thermoresponsive polymeric nanomaterials for drug release applications via hyperthermia technique

In this thesis, magnetic and thermosensitive polymeric nanomaterials were developed for drug release applications using the hyperthermia technique. In the synthesized magnetic and thermosensitive polymeric material, magnetic nanoparticles served as the support material and were modified with thermosensitive poly(ethylene glycol)-b-poly(2-(dimethylamino)ethyl methacrylate) (PEG-b-PDMAEMA) copolymers. Magnetic nanoparticles were synthesized via co-precipitation and characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), Fourier transform infrared spectrometry (FTIR), and thermogravimetric analysis (TGA). Thermosensitive PEG-b-PDMAEMA block copolymers with varying chain lengths were synthesized using Atom Transfer Radical Polymerization (ATRP). The structures and molecular weights of the synthesized copolymers were determined via FTIR, 1H-NMR spectroscopy, and gel permeation chromatography (GPC). The thermosensitivity of PEG-b-PDMAEMA copolymers was evaluated by measuring their Lower Critical Solution Temperature (LCST). Among the synthesized copolymers, PEG-b-PDMAEMA93 was identified as the most suitable for hyperthermia applications. To prevent undesired reactions, the magnetic nanoparticles were modified with PEG-b-PDMAEMA copolymers. FTIR, TGA, and TEM analyses confirmed the successful modification, with a copolymer layer of approximately 5.26% and a thickness of ~5 nm. Additionally, the polymerization of PEG-b-PDMAEMA via ATRP and the interaction mechanisms between the magnetic nanoparticles and PEG-b-PDMAEMA block copolymer were analyzed using Density Functional Theory (DFT) calculations. The hyperthermia properties of the synthesized magnetic nanoparticles and polymeric nanomaterials having magnetic and thermosensitive properties were assessed using a heat induction device generating an alternating current magnetic field (ACMF) of 0.745 kA/m at a frequency of 120 kHz. The hyperthermia performance of both bare and polymer-modified magnetic nanoparticles was optimized at 25°C and 37°C. Finally, the drug release behavior of the synthesized magnetic and thermosensitive polymeric nanomaterials (MNP/PEG-b-PDMAEMA) was investigated for two drug analogs, methylene blue (MB) and doxorubicin (DOX), under varying conditions of temperature, pH (5.5 and 7.4), and magnetic field. The highest drug release was observed at pH 5.5 under magnetic hyperthermia, reaching 42.29% for MB and 43.06% for DOX.