Aptamers, short stretches of DNA or RNA that can act much like antibodies, have shown promise as targeting agents for selective nanoparticle trafficking to tumors.
Their ability to recognize and bind to tumor-specific molecules is undisputed, but the strength with which aptamers bind to their molecular targets is often insufficient to act as an effective targeting agent under clinically relevant conditions.
Now, a research team headed by Weihong Tan, Ph.D., at the University of Florida has shown that adding up to 80 aptamers on a single gold/silver nanorod increases the binding ability of this construct by at least 26-fold compared with that of an individual aptamer. Using dye-labeled aptamers, the investigators also were able to produce a cancer-detecting probe whose fluorescent signal is more than 300 times greater than that produced by individual dye-labeled aptamers. This work was published in the journal Analytical Chemistry.
In earlier work, Tan and his colleagues had shown that aptamer-labeled magnetic nanoparticles could be used to separate cancer cells from a mixture of normal and malignant cells. In the current study, he and his colleagues have extended the utility of aptamer targeting by demonstrating that multiple copies of an aptamer, when distributed along the surface of a nanorod, dramatically increase the binding affinity of the nanoscale construct through cooperative binding.