(i) Magnetic nanoparticles based hyperthermia treatment of cancer
       Hyperthermia treatment is a promising therapy for cancer where the temperature of the tumor tissue is raised slightly above physiological temperature i.e. about 42-46oC by artificial means. Its effectiveness alone and in combination with other therapeutic modalities like chemotherapies and radiotherapies has been well recognized in medicine. But still its wide clinical use has been restricted due to lack of well-established thermal deposition system, invasiveness of treatment, nonhomogenous distribution of temperature within the tumor, requirement of online monitoring of temperature and difficulty in achieving therapeutic temperature within the target tissues. Further, heating the tumor tissue without damaging the surrounding structures has been a challenge to scientists. In this respect magnetic materials have been exploited as regional hyperthermia treatment modality. This is based on the fact that when magnetic materials are exposed to an AC magnetic field it generates heat. The heating occurs due to magnetic losses in the form of hysteresis loss, Neel loss and Brownian loss. Magnetic materials can be used as bulk as well as in the form of small particles. But bulk magnetic materials have been replaced by small magnetic particles preferably nanomagnetic materials due to their favorable magnetic properties in relation to hyperthermia treatment and ease of administration in the target tissues. Hence, the current research at IIT Bombay has been focused on the use of nanomagnetic materials in the form of magnetic fluids for hyperthermia treatment of cancer.
       (ii) Magnetic nanoparticle based MRI contrast agent
       Iron oxide (IO) particles are routinely used in clinics as a contrast agent (eg, Feridex; Berlex Laboratories, Wayne, NJ) for magnetic resonance imaging (MRI). Iron oxide particles shorten the effective transverse relaxation time (T2) of tissues that take up these particles by inducing magnetic field inhomogeneity around the IOs. The presence of IOs can be detected via signal decreases or void (ie, the image becomes darker) on T2-weighted MR images. Compared with another category of MRI contrast agent, represented by gadolinium diethyltriaminepentaacteic acid (Gd-DTPA), which primarily shortens longitudinal relaxation time (T1) resulting in intensity enhancement, IO?s detection is more sensitive. However, it would be most effective if magnetic nanoparticle based hyperthermia treatment of cancer is coupled with MRI as for both the purpose similar core material (iron oxide) is needed. But properties in relation to both hyperthermia treatment and MRI have to be tuned. Hence, more intense research is required for development of versatile magnetic nanoparticle which could serve different purpose simultaneously.
       (iii) Delivery of drugs
       a. Magnetic nanoparticles attached with drugs
       It has been found that hyperthermia increases the effectiveness of chemotherapy treatment of cancers. It would be ideal if hyperthermia treatment is combined with chemotherapy. This can be achieved by attaching drugs with magnetic nanoparticles and thereafter exposing to AC magnetic field to generate heat to the therapeutic temperature inside tumor. Again, magnetic drug targeting is also a prospective field of targeted drug delivery where distribution of drug attached with magnetic nanoparticles within the body is manipulated by external magnetic field. However, if magnetic particles attached with drugs can be concentrated into desired area by an external magnetic filed and thereafter exposed to AC magnetic filed, more effective therapeutic outcome is expected.
       b. Liposome based delivery
       Liposome has been exploited extensively for drug delivery purposes. Liposomes have also been used for efficient delivery of magnetic particles (known as magnetoliposomes). However, life of magnetic particles as well as liposomes is very short in vivo. So, long circulating liposomes (stealth liposome) are necessary for efficient delivery for which long chain polymer has to be attached to the liposome. It would be very beneficial if long circulating magnetoliposomes encapsulating drugs are made. Drugs can be incorporated either in the bilayer or inner aqueous chamber of liposomes depending on the polarity of drug molecule.
       (iv) Targeted delivery of magnetic nanoparticles along with drug
       Targeting of therapeutic agents is necessary for maximum utilization thereby reducing dose and avoid unwanted adverse effects due to higher doses. Magnetic drug targeting is as efficient targeting procedure (discussed above). Targeting through monoclonal antibody is also used for targeting diiferent drugs / biological molecules to their desired site. However folic acid mediated targeting has been emphasized in recent years as no of cancers show higher expression of folic acid receptors. Moreover, folic acid is non antigenic, cheap and easily available, easy for chemical modification. Hence, folic acid targeted stealth liposomes containing drugs as well as magnetic nanoparticles could be the smartest vehicle for serving efficient drug delivery, effective hyperthermia treatment as well as chemotherapy of cancers.