Synthesis and characterization of Iron-doped hydroxyapatite nanoparticles with superparamagnetic behaviour.

Cancer is regarded as the disease that killed more people in the last decade, with a number of victims which increase every year. Beneath all possible forms of it, in this work the focus is put on bone cancer, not so common but still accounting a large number of victims. Several investigations are nowadays performed to increase the chances of detection and prevention, this being always the best way to deal with cancer cells. However, it is not always easy to detect and sometimes medical intervention to cure the pathology is needed. For this reason, a big branch of research is focus on the discovery of new medical solution able to deal with different kind of cancer. For what concerns bone cancer, one of the main investigated cure deals with hyperthermia treatment. This treatment relies on cancer cells weaker resistance to high temperature and x-rays when compared to viable one. In fact with a permanence of a temperature higher than 42°C enzymatic process that keep cells alive stop working, determining the selective death of cells. Therefore, oxide nanoparticles are used to treat some kind of cancer. These particles are injected into the blood and then guide using the magnetic field to the application site where using an alternate magnetic field they are heated up until the temperature needed to kill tumoral cells. These particles are able to show super-paramagnetic behaviour which is essential to fulfil the proper increase of temperature in a required range of time. In fact high temperature can determine the death also of healthy cell on the long term. Another crucial aspect to be considered is that super-paramagnetic particles are able to switch off their magnetization instantly when the external field is removed, avoiding the risk of particles agglomeration which could heavily damage the organism. It is therefore important to use a biocompatible material, this being a crucial aspect in application when the material is in contact with human body. So the perfect candidate should show biocompatibility and super-paramagnetic behaviour. For this purpose iron doped hydroxyapatite are synthesized, in different composition and varying the sintering temperature studying how these two parameters influence final properties of the synthesized material. The process chosen for the production is the sol-gel process, this being an easy-controllable, not complicate and more economic process when compared to precipitation of microwave assisted. In this sense, particles are investigated through several tests, carried on with the object of testing the actual possibility of material application in hyperthermia treatment as well as the composition and structure of the final product. Unfortunately none of the synthesized powders seem able to show the required super-paramagnetic behaviour, not guaranteeing the desired increase in temperature till 42°C. However, the research proved to be useful for other important discoveries. First of all, varying the composition of powder by changing the amount of reagents used in the beginning of the sol-process it is possible to influence biocompatibility of material. In fact, increasing the amount of iron incorporated inside hydroxyapatite it is possible to increment the biocompatibility of samples produced. This being very interesting and important also in case of other iron doped hydroxyapatite where biocompatibility is a high requirement, in drug delivery for instance.