Study: Nanorods show more targeted drug delivery in vivo than spheres

A study shows that nanorods have a greater effect on diseases such as cancer.--Courtesy of Peter Allen, UCSB

Researchers at the University of California in Santa Barbara have found that nanoparticles shaped as "rods" as opposed to spheres are more effective as drug-delivery vehicles to the thin inside wall of blood vessels in the lung and brain.

The best shape for nanoparticles is a continuing debate among engineers, but the in vivo study from the Sanford-Burnham Medical Research Institute's Erkki Ruoslahti and Samir Mitragotri demonstrated that nanorods adhere more effectively to the endothelial cells that make up the inside wall of blood vessels, allowing more of the binding sites to interact with the cells to treat diseases such as cancer, cardiovascular diseases, inflammation and oxidative stress.

The idea is that the stretched-out nanoparticles have a greater surface area with which to bind to endothelial cells in the blood vessel, according to the study in the journal Proceedings of the National Academy of Sciences. Spherical particles of the same size, on the other hand, may be limited by the curvature of their surfaces. The scientists found that nanorods doubled accumulation at a site over nanospheres with the same targeting antibody.

"While nanoparticle shape has been shown to impact cellular uptake, the latest study shows that specific tissues can be targeted by controlling the shape of nanoparticles," Mitragotri said in a statement. "Keeping the material, volume and the targeting antibody the same, a simple change in the shape of the nanoparticle enhances its ability to target specific tissues."

Earlier this year, engineers in Mitragotri's lab found in a study of breast cancer treatments that the chemotherapy camptothecin coated with the antibody trastuzumab were up to 10,000 times more effective when contained in a rod-shaped nanoparticle than trastuzumab alone and 10 times more effective than camptothecin alone.

- here's the UC Santa Barbara release
- and here's the PNAS abstract
- and the February breast cancer study