**2.1. Status of nanomedicine**

102 Hyperthermia

diminishing, disappearing of the tumors or at least growing stop. Thermal methods include radiofrequency ablation (RFA), focused ultrasound thermo-therapy, laser-induced thermal

The thermal therapy can provide a minimal invasive alternative to conventional surgical treatment of solid tumors. In addition, the thermal therapeutic procedures are relatively simple to perform and therefore have the potential to improve recovery times and reduce the complication rates and hospital stays *(Hirsch et al., 2003)*. Although, the thermal methods offer several advantages, nevertheless have some of limitations. For example, the tumor volume and speed of ultra-sound thermo therapy is limited by the potential destruction of normal tissue in the near field between the target and the ultrasound probe. Radiofrequency ablation and microwaves approaches suffer from common limitations that are intervening tissue problems. On other wards, the heating effects from these sources are non-specific. In addition, the energy deposition is often much slower with these moieties serving to increase

the treatment time and generate less sharp lesion boundaries *(Ko¨hrmann et al., 2002)*.

To overcome these problems, new techniques in the field of nanoscience, nanotechnology and nanomedicine are now developing into treatment approach based on internal heating of tissue such as magnetic fluid hyperthermia (MFH), which in turn based on internal heating sources. In order to achieve the optimal effectiveness, this approach requires photo-thermal convectors to allow heat production within a localized region at lower incident energies. This requires development of particular particles that have highly magnetic properties such as Super-paramagnetic Iron Oxide Nanoparticles Fe3O4 (SPIO NPs). During this approach surrounding healthy cells are capable of surviving exposure to temperatures up to around 46.5°C and more readily able to dissipate heat and maintain a normal temperature while the targeted tumor tissues have a higher thermal sensitivity than normal tissue because of experience difficulty in dissipating heat due to the disorganized and compact vascular structure (reduced blood flow), anaerobic metabolism (acidosis), and nutrient depletion. So an irreversible damage to diseased cells occurs at temperatures in a range from

Nanomedicine stands at the boundaries between the physical, the chemical, biological and medical sciences. It originated from the imaginative idea that robots and other related machines at the nanometer scale could be designed, fabricated and introduced into the human body for repairing malignant cells at the molecular level. According to its original vision, nanomedicine is a process including the diagnosis, treatment and prevention of diseases and traumatic injuries, and the preservation and improvement of human health, using molecular tools and molecular knowledge of the human body (*Freitas 2005*). The progress in both nanoscience and nanotechnology makes nanomedicine practical. From a technical viewpoint, nanomedicine consists of the applications of particles and systems at the nanometer scale for the detection and treatment of diseases at the molecular level, and it plays an essential role in eliminating suffering and death from many fatal diseases, such as

therapy and magnetic thermal ablation *(Hilger et al., 2002)*.

approximately 40°C to about 46°C (Yu-Fen *et al., 2008*).

**2. Nanomedicine and magnetic nanomaterials** 

Nanomedicine has developed in numerous directions, and it has been fully acknowledged that the capability of structuring materials at the molecular scale greatly benefits the research and practice of medicine. However, nanomedicine is a long-term expectation. Before nanomedicine can be used in clinics, fundamental mechanisms of nanomedicine should be fully investigated, and clinical trials and validation procedures should be strictly conducted. Though, it is possible that some biological entities, such as proteins, DNA and other bio-polymers, could be directly used for biosensor applications, nevertheless some serious issues, such as biocompatibility and robustness, may hinder the progress of these efforts. Though in many areas, such as disease diagnosis, targeted drug delivery and molecular imaging, clinical trials of some nanomedicine products are being made, the clinical applications of these techniques, which require rigorous testing and validation procedures, may not be realized in the near future (Royal Society and Royal Academy of Engineering 2004). At all events, it should be noted that although the applications of nanomaterials in biology and medicine are in an embryo stage, it is the great promise of nanomedicine that has inspired researchers to extensively investigate the interfaces between nanotechnology, biology and medicine (*Satyanarayana, 2005*).
