Tuneable thermoresponsive hybrid magnetic nanoparticles: preparation, characterization and drug release characteristics

Abstract

BACKGROUND Thermo responsive hybrid Ni0.5Zn0.5Fe2O4 magnetic hydrogel particles based on PEG-g-poly(NIPAM-co-AMPS) were synthesized by soap free emulsion polymerization of N-isopropylacrylamide (NIPAM) and 2-acrylamido-2-methylpropane sulphonic acid (AMPS) via free radical mechanism using polyethylene glycol (PEG) as macro-initiator in presence of N,N'-Methylenebisacrylamide (MBA) as cross linking agent. The thermo responsive pure copolymers and hybrid particles were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermo Gravimetric Analysis (TGA), and Vibrating Sample Magnetometer (VSM) and Dynamic Light Scattering (DLS). Furthermore, the hybrid magnetic particles were used to study the drug release characteristics of theophylline (TPH) as model drug at pH 7.4 and temperature 37°C. RESULTS The sizes of the particles were found to be 121 nm to 245 nm at 50°C and 580 nm to 694 nm at 25°C depending on the amount of AMPS present in the hybrid particles. The volume phase transition temperature (VPTT) of the hybrid particles was tuned above body temperature from 33°C to 41°C. The hybrid magnetic particles with incorporation of AMPS in polymer chains showed high theophylline loading capacity as compare to that of PEG-g-PNIPAM. The entrapment efficiency of theophylline was increasing with increase of AMPS concentration. The releasing capacity of theophylline was decreased with increase in AMPS concentration and observed to have sustained drug release profile without initial burst release. CONCLUSIONS The prepared hybrid particles showed both the temperature sensitive as well as superparamagnetic properties, thus found to be a suitable candidate for applications in targeted drug delivery system.