Thermal and microwave synthesized SPIONs: Energy effects on the efficiency of nano drug carriers

Superparamagnetic iron oxide nanoparticles (SPIONs) were optimally synthesized employing two energy sources viz. thermal and microwave using low temperature co-precipitation process. Both methods yielded particles with optimum physicochemical properties for biomedical applications like smaller size (~6--7 nm), narrow size distribution (standard deviation ~1.6-1.7 nm) and good magnetic parameters (saturation magnetisation ~53 emu/g at 9 T). Simplified process made use of domestic oven. After coating by amino acid serine, successful loading (>8 wt%) of drug Doxorubicin was achieved for both SPIONs. Microwave sample showed equivalently efficient drug loading despite half the serine coating. Findings were confirmed by various techniques like X-ray diffraction (XRD), transmission electron microscopy (TEM), Vibrating sample magnetometer (VSM) and thermo gravimetric analysis (TGA) etc. Differences in thermal homogeneities and efficiency of heat transfer between two energy modes affected the properties of synthesized SPIONs. Differences were observed in amount of serine coating, drug release behaviour and in vitro experiments on A549 cells like internalisation and cell viability data. About 59 and 39% pH and time dependent drug release at pH 5 was obtained for thermal and microwave sample respectively. In vitro experiments confirmed the successful internalisation and cell death, supporting the suitability of SPIONS as efficient targeted drug carriers. Despite lesser drug release, microwave sample showed comparable in vitro results. Study emphasizes the role and importance of energy in affecting the efficiency and functional behaviour of SPIONs as nano drug carriers. Being biocompatible and magnetic these particles can be applied successfully as efficient targeted drug delivery agents.