Method and system for characterizing extracellular vesicles
A method for characterizing extracellular vesicles at an individual level is described. It comprises obtaining a sample comprising extracellular vesicles to be characterized and functionalizing the extracellular vesicles with plasmonic nanoparticles or a plasmonic coating. The method further comprises irradiating the individual extracellular vesicles with a laser beam and detecting a surface enhanced Raman spectroscopy signal from said individual extracellular vesicle.
1. A method for characterizing extracellular vesicles at an individual level, the method comprising
obtaining a sample comprising extracellular vesicles to be characterized,
functionalizing the extracellular vesicles with plasmonic material by providing a coating of plasmonic material on the extracellular vesicles or applying at least one of plasmonic nanoparticles to the membrane, in a phospholipid layer or in the lumen of the extracellular vesicles,
irradiating the functionalized individual extracellular vesicles with a laser beam and detecting a surface enhanced Raman spectroscopy signal from said functionalized individual extracellular vesicles, and
identifying individual extracellular vesicles of the sample from the surface enhanced Raman spectroscopy signal.
2. A method according to claim 1 , wherein the plasmonic material are plasmonic nanoparticles.
3. A method according to claim 1 , wherein the functionalized individual extracellular vesicles are functionalized such that they are physico-chemically repelling each other.
4. A method according to claim 3 , wherein the functionalized individual extracellular vesicles are functionalized such that they are separated from each other based on charge based repelling or based on steric effects.
5. A method according to claim 1 , wherein the functionalized extracellular vesicles are colloidal stable in suspension.
6. A method according to claim 1 , wherein the plasmonic material is functionalized with a positively charged small molecule and/or wherein the plasmonic material is functionalized using lipophilic or amphiphilic molecules for insertion into the phospholipid bilayer of the extracellular vesicles and/or wherein the plasmonic material is functionalized using particular targeting ligands for targeting extracellular vesicles.
7. A method according to claim 1 , wherein the functionalized extracellular vesicles are, prior to performing said surface enhanced Raman scattering measurements, absorbed to a substrate so as to immobilize them and wherein for performing said surface enhanced Raman scattering measurements, the irradiation beam is scanned over the substrate for individually irradiating the coated extracellular vesicles.
8. A method according to claim 1 , wherein the functionalized extracellular vesicles are in suspension, during said performing said surface enhanced Raman scattering measurements, wherein said surface enhanced Raman scattering measurements are performed on individual extracellular vesicles when these diffuse through the irradiation beam or are trapped.
9. A method according to claim 1 , wherein the plasmonic material are metal based nanoparticles such as silver or titanium particles or wherein the plasmonic particles are carbon-based particles such as graphene particles, graphene oxide particles like graphene oxide nanosheets, carbon nanotubes, carbon nanodots, or fullerenes.
10. A method according to claim 1 , wherein the plasmonic particles have a diameter within the range 1 to 100 nm.
11. A method according to claim 1 , wherein the extracellular vesicles are exosomes.
12. A method according to claim 1 , wherein after said detecting a surface enhanced Raman spectroscopy signal from said individual extracellular vesicle, the method comprises comparing said surface enhanced Raman spectroscopy signal with a library of surface enhanced Raman spectroscopy signals for identifying the individual extracellular vesicle.
13. A method according to claim 1 , wherein functionalizing the extracellular vesicles with plasmonic material comprises binding gold nanoparticles to the surface of the extracellular vesicle and providing a plasmonic metal coating on the gold nanoparticles.
14. A method according to claim 13 , wherein the gold nanoparticles are coated with a Ag metal layer the Ag metal coating having a thickness in the range 0.5-100 nm.
15. A microfluidic chip for characterization of extracellular vesicles, the microfluidic chip comprising
an inlet for obtaining a sample comprising said extracellular vesicles to be characterized,
plasmonic material contactable with said sample for forming a shell of plasmonic material around and/or for or applying at least one of plasmonic nanoparticles to the membrane, in a phospholipid layer or in the lumen of the extracellular vesicles,
a microfluidic channel for guiding the functionalized extracellular vesicles to an irradiation position in the microfluidic chip, and
the microfluidic chip being adapted for allowing laser radiation in the microfluidic chip at said irradiation position.