GAINESVILLE, Fla.—Although researchers are increasingly using aptamers as high-specificity molecular probes, they generally need purified targets to generate these modified nucleic acids. In the Proceedings of the National Academy of Sciences, however, researchers at the University of Florida describe a way to use key molecular differences between two cell types to effectively "pan" for tissue-specific aptamers without foreknowledge of the molecular targets.
The group mixed a library of random single-stranded DNA molecules with cultured leukemia cells, washed away unbound aptamers, and eluted the bound aptamers. They then incubated these oligonucleotides with a control cell line and collected the aptamers that did not bind these cells. The scientists PCR amplified this subset of aptamers and repeated the selection cycle several more times, monitoring cell-aptamer interaction with flow cytometry.
