BILL ARSENAULT
Nanotechnology is poised to completely transform the practice of medicine. The unique physical properties of nanomaterials hold multifaceted promise for medical applications, making nanomedicine a game-changing subfield. Researchers are developing new methods that will facilitate tracking disease markers at very early stages and monitoring them as a disease progresses. This type of tracking will bring us closer to the implementation of personalized medicine, in which we will differentiate patient populations based upon their responsiveness to candidate therapies. Recent advances in nanotechnology also offer the possibility of exquisite selectivity in the delivery of therapeutic payloads.
These approaches have the potential to substantially lower health-care and pharmaceutical-development costs, because many expensive therapeutics are now broadly and needlessly administered, even when their effectiveness is questionable for a significant portion of the population. Furthermore, the versatility and compact size of certain nano-enabled diagnostic methods could reduce the need for massive, specialized...
A tenet of nanotechnology is that the fastest way to develop materials with new properties is through the miniaturization of existing materials. For example, gold is a material used by jewelers and nanoscientists alike because it does not degrade or react with water or air the way iron rusts. When a chunk of gold is reduced to nanoscale particles and dispersed in solution, it loses its familiar yellow glint and turns blood red. Because the optical properties of gold particles change as they are reduced in size and because gold is nontoxic and can be custom-coated with fragments of DNA, RNA, or protein, these nanoparticles have many promising uses in biosensors and diagnostic tools, and as drug-delivery vehicles.
Advances in nanotechnology offer the possibility of exquisite selectivity in the delivery of therapeutic payloads.
Part of nanomedicine’s allure is the possibility of faster routes to the treatment of the most pressing medical problems. Take, for example, the development of drugs that modulate gene expression; a few decades of research have shown the potential for treating and even curing some of the most debilitating diseases by targeting them at their molecular roots. We are unraveling the cellular and molecular mechanisms behind cardiovascular disease, neurological disorders like Alzheimer’s disease, and many forms of cancer. However, we have learned that conventional gene-regulation strategies based upon polymer or viral delivery approaches are not easy to implement. They suffer from poor targeting capabilities, require expensive custom-synthesized nucleic acids to stabilize the active therapeutics, and often cause significant toxicity and immunogenicity.
AuraSense, a company that I founded with Shad Thaxton, is developing one of the technologies my lab invented—a new class of DNA- or RNA-based therapeutics with built in delivery capabilities—into a topical gene-delivery treatment for skin diseases such as psoriasis and melanoma. Current technology requires the use of needles and excruciatingly painful micro-injections to deliver genetic material as drugs. However, by using nanoengineered gold particles with specific DNA or RNA affixed to their surfaces, the nucleic acid therapeutics of interest can be topically (and painlessly) delivered to the skin. This application allows us to target diseased cells at the genetic level, up- or downregulating pathways based upon the nucleic acids on the surface of the particles. These constructs also show promise as systemic treatments for patients with life-threatening diseases such as glioblastoma, liver cancer, and bladder cancer, to name only a few.
On the diagnostic side, we are discovering powerful new ways of detecting and tracking disease biomarkers at very early stages—stages that cannot be detected with conventional tools. Genetic and protein-based tests developed by companies like Nanosphere, which Robert Letsinger and I cofounded, rely upon the exquisite sensitivity and selectivity of nanoparticle probes to help identify and target disease-related genetic sequences or proteins. The probes’ minute size and ease of use make it possible for a physician to perform a diagnosis concurrently with treatment, rather than sending samples to a remote lab to process via existing molecular diagnostic methods, such as ELISA or PCR-based techniques, prior to any treatment decisions. This new technology is allowing medical researchers and clinicians to diagnose heart disease or potential heart failure at the very earliest stages, when therapeutics can be more effective.
The next decade of nanomedicine will see the continued transition of therapeutic candidates from the bench top to the clinic. Examples like the FDA-approved Abraxane, for treatment of metastatic breast cancer, have shown that combining a known anticancer drug with albumin nanoparticles can have significant impact in terms of efficacy, simply by making it possible to adjust the drug’s solubility and dissolution rates. Because nanoparticles are larger than small-molecule drugs, they can carry both a targeting molecule and a therapeutic payload within one entity. They can be designed to have sizes, shapes, and internal structures that are conducive to effective delivery of therapy. Based on these ideas, companies like Liquidia and Calando are developing very promising nanotechnologies for the treatment of a vast array of diseases, including several forms of cancer, infectious diseases, and respiratory ailments.
Nanostructures are also showing significant promise as “theranostic” systems, which provide the ability to image or detect disease in vivo, deliver targeted therapy triggered by the diagnostic discovery, and then monitor the response—but this technology is still being developed at the university level. These multifunctional systems rely on specific attributes of nanostructures, including their shape, surface functionality, ability to move throughout the body, and specificity. These properties are difficult, if not impossible, to realize with macroscopic and molecular approaches. As they continue to reach the clinic, nanotechnology innovations will help redefine the practice of medicine as we know it today.
Chad Mirkin is a professor at Northwestern University, director of the university’s International Institute for Nanotechnology, and a member of President Obama’s Council of Advisors on Science and Technology.
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