Project Summary/Abstract The aim of this project is to acquire a Beckman CytoFLEX LX flow cytometer for small particle and multicolor flow cytometry. The University of Delaware Flow Cytometry Core has two fluorescence-activated cell sorters (BD FACS Aria Fusions), but does not have a dedicated, modern analytical flow cytometer for multicolor flow cytometry panels and small particle (~80 nm) analyses. The existing BD FACS Aria Fusion can resolve only up to ~300-1000 nm particles, a range that does not achieve the lower limits of small particle and EV biology. Acquiring an instrument with FSC detectors specializing in small particle detection will make it possible to use flow cytometry to study the rapidly growing field of research on extracellular vesicles (EV) and exosomes. It will open up new avenues of research for UDEL investigators studying EV release in human and mouse bone marrow cells, pancreatic cancer cells, bacteria, fungi as well as other small particles, such as virus-like particles and nanoparticles for drug delivery. With a complement of 4 active lasers (and detectors) similar to the current Aria Fusions at the core labs, existing users can efficiently transition to the CytoFLEX LX for dedicated analysis purposes. Additionally, new and existing users will also benefit from the CytoFLEX LX’s highly sensitive avalanche photodiode (APDs) technology which provide a greater sensitivity and better resolution of signal-to- noise ratios compared to existing PMT technology inherent to other flow cytometers. Furthermore, it will greatly expand the UD flow cytometry core’s capabilities to conduct multiparametric single cell analyses with multicolor flow cytometry panels to reveal clinical and translationally relevant findings.