DNA barcoded nanoparticles for high throughput in vivo nanoparticle delivery [185]. (A) Using high-throughput fluidic mixing, nanoparticles are formulated to carry unique DNA barcodes. (B) Many nanoparticles can be formulated in a single day; each nanoparticle chemical structure carries a distinct barcode. Particles are then combined and administered simultaneously to mice. Tissues are then isolated, and delivery is quantified by sequencing the barcodes. In this example, nanoparticle 1 delivers to the lungs, nanoparticle 2 delivers to the liver, and nanoparticle N delivers to the heart. (C) This DNA barcode system enables multiplexed nanoparticle-targeting studies in vivo, improving upon the current practice, which relies on in vitro nanoparticle screening to identify lead candidates. Printed with permission from United States National Academy of Sciences.