AREAS OF INTEREST:

• Gold nanoshells
• Cancer therapy
• Nanoshell-protein conjugates
• Homogenous whole blood diagnostic assays

RESEARCH:

Leon Hirsch received his B.E. in Biomedical Engineering at Vanderbilt University in Nashville in 1998, and is currently finishing up his doctorate in Bioengineering at Rice. Leon has spent the past 5 years investigation numerous diagnostic and therapeutic applications for metal nanoshells in Biomedicine. His work exploits that fact that nanoshells can be fabricated with intense optical absorption/scattering within the near infrared “water window” region of light where tissue is relatively transparent due to tissue’s lack of near infrared absorbing chromophores. This makes for a material that is both easy to detect within tissue for diagnostic applications, as well as a material that is capable of near infrared optical excitation for therapeutics.

His diagnostic work has led to the successful design and development of a simple whole blood analytical tool that can quantitatively detect proteins within whole blood after 10-30 minutes with detection limits of 100 pg/ml. NIR absorbing nanoshells conjugated with antibodies were easily detectable in whole blood samples using photometry. When antibody-nanoshell conjugates were introduced to whole blood samples containing analyte of different concentration, photometric analysis revealed that the nanoshells underwent aggregation in a quantitative fashion. The benefits of this new technology could extend into public health, biological defense, and clinical applications, where there is a large demand for rapid, high throughput, analytical tools capable of detecting small quantities of analyte in biological samples.

If enough NIR light is administered to NIR absorbing nanoshells, they heat up. This is the foundation of a cancer therapy project that Leon has been working on in conjunction with numerous other research groups at Rice as well as M.D. Anderson. When nanoshells accumulate at tumor sites, sufficient delivery of NIR light causes the nanoshells to heat the tumor tissue with irreversible damage, while surrounding healthy tissues remain undamaged. Meanwhile, tumors void of nanoshells displayed minimal heating, incapable of inducing tissue damage. Ultimately, we envision a targeted cancer therapeutic system where nanoshells conjugated with tumor targeting molecules could be systemically injected into a cancer patient’s bloodstream, where the nanoshells would circulate and preferentially accumulate at the tumor site. With sufficient accumulation, NIR irradiation of the bulk tissue would result in the isolated, selective photothermal heating of the nanoshell-laden tumors. This system would provide a nonsurgical, targeted therapy, to tumors that may otherwise be considered inoperable.

Lee is most easily reached via electronic mail: lrhirsch@rice.edu