Synthesis and characterization of ZnFe₂O₄ nanoparticles and its biomedical applications

Biomedical applications of ZnFe₂O₄ nanoparticle are preferable among all kinds of ferrites due to the compatibility of Zn²⁺ ions for human bodies. We have followed the soft chemical route to synthesize chitosan and PEG coated ZnFe₂O₄ nanoparticles and also the chitosan-coated-nanoparticles encapsulated with liposome. X-ray diffraction studies by the Mo K_α target, showed the formation of single phase spinel structure. The lattice parameter turned out to be 8.48Å and grain size ~ 4.8 nm (± 0.1 nm). Similar particle size was observed by transmission electron microscope analysis. HRTEM studies showed the distinct lattice fringes thus confirming the good crystallinity of the synthesized nanoparticles. M-H curve at room temperature showed the prepared sample was superparamagnetic in nature, which is also confirmed by the doublets of Mössbauer spectroscopy. Relaxivity values (r₂) of Chitosan and PEG coated ZnFe₂O₄ nanoparticles are 68 and 76 mM^-1s^-1 respectively. In order to achieve further biocompatibility the chitosan-coated-nanoparticles were encapsulated with liposome. The r₂ relaxivity was found as 54mM^-1s^-1. MR images obtained from the in vitro experiments based on phantoms demonstrated good contrast enhancement. Induction heating of bare and coated particles was investigated to reveal the self heating temperature rising properties of ZnFe₂O₄ nanoparticles.