Rare‐Earth Upconverting Nanobarcodes for Multiplexed Biological Detection

Rare-earth upconversion nanobarcodes (UPNBs) have been developed for multi­plexed signaling. There is no optical cross talk between the upconversion optical code and any reporter dyes. The midrange IR radiation used to excite the upconversion materials does not excite dyes that absorb in the visible and UV region and, conversely, the upconversion materials are not excited by the visible lasers used to excite the organic dyes.