Chapter 12 - Inorganic nanobiomaterials for medical imaging

Abstract

Nanotechnology involves the creation and use of materials at the level of molecules and atoms, therefore nanotechnology is spreading its annexes to different parts of biomedical applications. The practice of medical imaging has been made possible by advances not only in diagnostic equipment and investigative techniques, but also in the inorganic nanobiomaterials which are being used as various imaging agents that permit visualization of the details of the internal structure using nanotechnology. When inorganic materials are reduced to nanoscale then these nanosized inorganic materials have superior physicochemical properties. For imaging agents it is essential to have rapid clearance from blood so as to obtain low background signals and good images. The surface charge and hydrodynamic diameter of the inorganic nanobiomaterial nanoparticles (NPs) in the presence of plasma proteins are important for their biodistribution, excretion, and rapid clearance from blood. Hence, researchers are now focusing on developing inorganic nanobiomaterial NPs for various medical imaging purposes such as X-ray contrasting agent, magnetic resonance imaging (MRI), positron emission tomography (PET), and ultrasound imaging. Iron oxide particles have been used as a contrasting agent for MRI for 20 years. Quantum dots (QDs) are another category of metal-based NPs which have been used for medical imaging purposes. Nanobiomaterials made from gold and silver have high tunable optical properties which make them suitable for medical imaging purposes. Hence twenty-first century inorganic nanobiomaterials are being extensively investigated for use in medical imaging.