Exosomes are extracellular vesicles (EVs) released by cells, which are present in biological fluids and in cell culture conditioned media. Their quantification and characterization are important steps with general international rules (see MISEV 2018 guidelines) recommending measurements from at least two of the following three parameters: particle number, protein, or lipid amount.
How do you characterize exosomes?
Exosomes isolated from a biological sample will have to be characterized; a large range of different techniques are available. Among them, nanoparticle tracking analysis (NTA) technology is a routine light scattering method to characterize EV sub-populations contributing to consistency and less variability in the published data from different laboratories.
For characterization of exosome samples, we recommend analysis of the number and size distribution as a fundamental step. In addition, combining this readout with the protein content of the sample can also provide a measure of sample purity.
What is nanoparticle tracking analysis (NTA) principle?
NTA is a technique used for the simultaneous measurement and analysis of the size and concentration of single nanoparticles with high precision, accuracy, and reproducibility.
A laser is directed at the sample solution which generates light scattering by the particles in the sample. The NTA software captures the Brownian motion of each individual particle in a recorded frame-by-frame video. Large and small particles have different diffusion movements in solution which allows for the measurement of the hydrodynamic diameter of each particle using the Stokes-Einstein equation.
Cell Guidance Systems service uses ZetaView®, a second-generation instrument from Particle Metrix GmbH, which performs rapid in vitro measurement of physical parameters, including size, surface charge, and concentration of particles.
The ZetaView® instrument has been designed to do an automated scanning NTA. For a more representative analysis, the software measures 11 distinct positions in each sample which provides further information than single-point assessments, thus contributing to repeatable and reproducible results. Furthermore, automated parameters for auto-alignment and autofocus ensure that the video quality is kept constant while the particle movement is recorded.
This technology is well suited for use in exosome characterization, as it allows for easy and quick measurements, and is compatible with low concentrated and polydisperse samples.
NTA size profiling service
The NTA service is performed in our laboratories by a team of highly qualified scientists within a very short timeframe, guaranteeing the researcher quick access to the EV characterization data. The service is performed with total transparency and all data and selected parameters are provided with the final report.
The selected NTA instrument allows for higher throughput and greater economy than other available instruments, enabling us to deliver a highly cost-effective service, so you will get all the results without the need to invest in your own instrument.
Whatever the sample and the exosome purification method used, an NTA profiling report can be generated!