Sticky-flares: real-time tracking of mRNAs... or of endosomes?
The article by Briley et al is the latest of several papers based on the use of oligonucleotide-capped gold nanoparticles (or Spherical Nucleic Acids, SNAs) to detect mRNA within cells (1). The technology was developed, published and patented by Prof Chad Mirkin and is commercialised under the trade name SmartFlare. Briefly, the SNAs are hybridised with fluorescent reporter strands (resulting in quenching of the fluorescence by the gold particles) and internalised into cells by endocytosis. The target RNA binds either with the SNA, releasing the reporter strand (SmartFlare) or, in the latest study, with the reporter strand itself, releasing the reporter-strand/target-RNA duplex (Sticky-flares).\n\nSince they enter cells by endocytosis, Sticky-flares (and SmartFlares) need to escape those compartments before they can report on mRNA levels in the cytosol. This essential step is currently not documented in the literature. To the contrary, we (2) ...