Evaluation of folate conjugated pegylated thermosensitive magnetic nanocomposites for tumor imaging and therapy.

Superparamagnetic iron oxide nanoparticles (SPIONs) have been receiving great attention lately in biomedical applications, such as in magnetic resonance imaging and drug delivery. However, their systemic administration still remains a challenge due to their hydrophobic nature with instances of aggregation leading to fast reticuloendothelial system (RES) uptake. In this study, magnetic nanocomposites with thermosensitive polymer have been investigated. Random polymers of N-isopropylacrylamide (NIPAAM), acrylic acid (AA) and PEGMA have been coated on SPIONs followed by conjugation with folic acid. Particles of ∼200 nm and low polydispersity 0.1-0.2 having a critical temperature (T(c)) of 44 °C were formed. Thermogravimetric and powder X-ray diffraction studies showed that the nanocomposites were composed of 90% cubic face-centered magnetite. Nearly 76.5% doxorubicin was loaded onto the nanoparticles by diffusion method. Drug release was higher at the hyperthermia temperature (72.42 ± 5.25% in 48 h) proving the thermoresponsive nature of the polymer. Folate conjugated samples showed a magnetization value of 32 emu/g as well as high r1 and r2 relaxivities in magnetic resonance imaging. R2 weighted images of nanocomposites were darker than the control with 20 μg/mL as the darkest. At this concentration the magnetic composites showed nearly 95% viability in L929 fibroblast cells. These thermoresponsive nanosystems with pegylated surfaces and size of ∼200 nm are therefore highly suitable for in vivo imaging and hyperthermia based drug delivery.