Some Rare Earth (RE) Substituted Potential Low-Tc Superparamagnetic Nanoparticle System for Self-Controlled Magnetic Fluid Hyperthermia Based Therapeutic Applications.

Clinical hyperthermia utilizes thermal destruction of cancer cells and requires the development of thermal homogeneity of 42-46 oC in the tumour tissues for their destruction. However effective treatment without destroying adjacent normal tissues is still a challenge, especially in local hyperthermia. Magnetic nanopaticles with tunable Curie temperature (Tc) have the potential to provide an answer to this challenge. Superparamagnetic particles having higher specific absorption rate (SAR) are magnetically targeted to the local tumour site through in vivo or ex vivo and can be used for heat induction when exposed to an alternating magnetic field. The demand for self-controlled hyperthermia is very high instead of externally adjusting the magnetic field in response to the desired temperature range of 42-46oC. Another challenge is to sustain particle in the specific site against the bodies major defence system, the reticulo-endothelial system (RES) until the heat treatment is over. More hydrophilic agents can resist this defence process and a layer of hydrophilic polymer chains is needed to be coated. It may be thermosensitive such that its melting temperature is chosen to be equal to the Curie temperature of the particles (42-46 oC) so that it can be used to assist in delivering chemotherapy drugs or radiosensitizing agents. The most common coatings like derivatives of dextran, PEG, PEO, PVA, PVME, ethyl cellulose, poloxamers, polyoxamines, human serum albumin etc., may be tested for their melting temperature, whether it is in the range of 42-46 oC, and the right candidates will be selected for coating.

In this context, some of the rare earth elements like gadolinium substituted spinel ferrites, viz.  ZnGdxFe2-xO4 are proposed to be synthesized by chemical route such as solgel method and the subsequent grafting of biopolymer shell around the nanoparticle core by plasma polymerization as well as solvent evaporation technique. The rare earth elements can considerably reduce the Tc. The XRD, TEM, VSM, SQUID etc., have to be performed for understanding the genuineness of the material. The talk will cover some of the above mentioned aspects of superparamagnetic nanoparticle system along with some preliminary experimental results obtained on certain spinel ferrites