Methods and systems of enhancing electromagnetic radiation signals from extracellular vesicles

A method of fluorescence imaging of individual target extracellular vesicles (EVs) on a substrate, the method comprising:

• obtaining a nano-plasmonic array comprising,
• a substrate,
• a plurality of nanostructures arranged in an array on a surface of the substrate, wherein the nanostructures comprise nanorods, nanodisks, nanopillars, nanogrooves, or any combination thereof, and
• one or more affinity ligands fixed on or adjacent to the nanostructures, wherein the affinity ligands specifically bind to EVs to bind the EVs to the nanostructures or to the substrate adjacent to the nanostructures;
• flowing a liquid sample over the nano-plasmonic array at a flow rate that enables EVs in the liquid sample, if any, to bind to the affinity ligands thus capturing the EVs on the nano-plasmonic array;
• labeling target EVs among EVs captured on the nano-plasmonic array with one or more different fluorescent reporter groups;
• exposing the labeled target EVs captured on the nano-plasmonic array to a first electromagnetic radiation thereby causing the target EVs, or fluorescent reporter groups on the target EVs, or both target EVs and fluorescent reporter groups on the target EVs, to emit, scatter, or reflect one or more fluorescent signals;
• receiving all or a portion of the one or more fluorescent signals, wherein the nanostructures in the nano-plasmonic array are arranged and dimensioned to amplify the fluorescent signals, thereby amplifying the fluorescent signals from individual target EVs on the substrate;
• and
• obtaining an image of one or more individual target EVs by receiving the amplified fluorescent signal.