Posted: June 15, 2007

Aptamer-targeted nanoparticles collect and detect cancer cells

(Nanowerk News) Using magnetic and fluorescent nanoparticles capable of binding tightly to molecules found only on the surface of cancer cells, a team of investigators at the University of Florida has developed a method for collecting and detecting multiple cancer cells from biological samples. This work could lead to new diagnostic assays for cancer and new methods for isolating cancer cells for further study.
Reporting its work in the journal Analytical Chemistry ("Aptamer-conjugated nanoparticles for the collection and detection of multiple cancer cells"), a research team headed by Weihong Tan, Ph.D., used short, synthetic molecules of DNA known as aptamers as cancer-targeting agents. This group has refined methods for creating aptamers, which resemble antibodies in their ability to recognize specific proteins, capable of binding only to specific types of cancer cells and not to healthy cells. These methods work even without knowing which cell surface molecules distinguish one type of cancer cell from another or from healthy cells.
For this set of experiments, the investigators used aptamers that bind to acute leukemia cells, Burkitt's lymphoma cells, and non-Hodgkin's B-cell lymphomas. They used mild coupling chemistry to attach each of these aptamers to both magnetic nanoparticles and fluorescent silica nanoparticles. The researchers used three different silica nanoparticles, each with a characteristic color and each attached to one of the three cancer-recognizing aptamers.
Starting with a mixture of cells, the investigators demonstrated that they could use the magnetic nanoparticles to produce pure extracts of each of the three types of cancers and detect each type of cell using the fluorescent nanoparticles. The researchers determined that they could reliably detect as few as 250 cells and upward of 40,000 cells. Separation and identification of cells from serum were completed in as little as 30 minutes.
In addition, the authors have published second paper detailing their work discovering and developing cancer-targeting aptamers ("Optimization and modifications of aptamers selected from live cancer cell lines").
Source: National Cancer Institute