This chapter basically reviews the basic principlesof magnetic nanoparticles, chemical synthetic pathways, its characterizationand stabilization methods. The design strategies, its performance andbiomedical applications are discussed. Magnetically responsivenanodevices have a crucial role in In-vivo applications like MRI, imaging of transplanted cells or tissuereconstruction, stem cell labeling and tracking in vivo, imaging-assisted drug and genedelivery, molecular targeting of chronic diseases such as atherosclerosis andcancer, disease therapy,safety and biocompatibility to name few. Toxicity of MNPs is multifactorial anddepends upon their composition, physicochemical properties such as size andsurface characteristics, route of administration, and dose. Knowledge about thecomplex issues involving physiological, physicochemical and molecular processesof magnetic nanosystems need to be considered for understanding the clinicaltoxicity These magneticnanosystems are of great advantage for nonsurgically removable neoplasia (i.e., brain cancers or hemorrhagic tumors)but limited to accessible tumor nodules.
Hence surface functionalization isimportant for target delivery because of specificity toward the target cellsoverexpressing unique surface receptors. The biocompatibility of nanoparticles must be assessed in vitro,prior to measuring their magnetic and relaxometric properties. Finally, thebiological kinetics (blood retention, organ uptake, clearance) andcontrast-enhancement effects of each new nanoparticulate system, must becarefully studied in vivo.
Nano carrier systemshave demonstrated to induce cytotoxicity and /or genotoxicity whereas theirantigenicity remains poorly characterized. Identification of best magnetic andirradiation technologies is the requirement for the efficient delivery ofmagnetic nanosystems. Emitters of magnetic fields are potentially expensive andhence remain the major challenge for daily clinical practice. Finally, theexpansion of hybrid imaging modalities (MRI/PET, MRI/luminescence, MRI/SPECT,MRI/echography), call for the development of multifunctional and increasinglycomplex imaging tracers. Huge progress has been observed in this area ofmagnetic nanosystem, but various challenges need to be addressed with respectto clinical medicine and ensure the smooth transition of these concepts fromlabs to market. Regulatory guidance enforce very strict requirements over thedesign, manufacturing, reproducibility, potential toxicity and pharmacokinetic performance of such magnetic nanosystems. In this context, the 2020 nanomedicineresearch outlook as viewed by the European Commission, is to establish astronger and faster transition of nanomedical R&D from a laboratory toclinical development and approval (www.etp-nanomedicine.