The latest article in our Current Concepts review series, “Nanomedicine,” comes from Drs. Betty Kim, James Rutka, and Warren Chan of the University of Toronto.
The field of nanomedicine aims to apply nanotechnology to the diagnosis and treatment of diseases at the molecular level.
• What do nanomaterials consist of?
Nanomaterials generally consist of metal atoms, nonmetal atoms, or a mixture of metal and nonmetal atoms, commonly referred to as metallic, organic, or semiconducting particles, respectively. The surface of nanomaterials is usually coated with polymers or biorecognition molecules for improved biocompatibility and selective targeting of biologic molecules.
• What physical feature is common to all nanomaterials?
A common feature of all nanomaterials is their large ratio of surface area to volume, which may be orders of magnitude greater than that of macroscopic materials. Cutting a 1-cm cube into 10(21) cubes that are each 1 nm will result in the same volume and mass, but the surface area will be increased by a factor of 10 million. Thus, the advantage of using nanomaterials as carriers is that their surface can be coated with many molecules.
Table 1. Examples of Nanomaterials in Clinical Use.
Morning Report Questions
Q: Why are nanoparticles particularly appropriate for use as radiocontrast agents?
A: Nanoparticles have a larger, localized magnetic field as compared with that of larger particles. This larger magnetic field can increase the contrast on imaging (MRI), since more protons interact in a larger field.
Q: Why are nanomaterials particularly suitable for use in chemotherapy?
A: Nanomaterials infused into the bloodstream can accumulate in tumors owing to the enhanced permeability and retention effect when the vasculature of immature tumors has pores smaller than 200 nm, permitting extravasation of nanoparticles from blood into tumor tissue. With nanomaterials, the high ratio of surface area to volume permits high surface loading of the therapeutic agent; in the case of organic nanomaterials, their hollow or porous core allows encapsulation of hundreds of drug molecules into a single carrier particle.