Nanoparticle tracking analysis

What is nanoparticle tracking analysis used for?

NTA is used to characterize particles within the particle size range of ~10 nm to ~1 µm. It is commonly used in drug-delivery studies, microbial analysis, toxicology, and viral studies, as well as industrial nanoparticle development and polymer research. 

Another application of nanoparticle tracking analysis is the detection and characterization of nanoparticles in food and water samples. It is one of the methods mentioned in the European Food Safety Authority’s (EFSA) guidelines for determining whether food materials contain nanoparticles, although electron microscopy (SEM or TEM) is used more often. 

How does nanoparticle tracking analysis work?

NTA works by illuminating the sample with a laser. The motions of the particles within the sample cause the light to be partially scattered, which is monitored using a microscope. A video of this process is recorded, which shows the Brownian motion of the particles over time. This provides a visual representation of the particles. The tracking of particles can also be used to calculate the particle size distribution within the sample. 

Sample requirements and preparation

NTA is typically carried out on samples consisting of particles within a suspension, meaning in most cases there is minimal preparation required. NTA can be carried out on suspensions with even a relatively low concentration of detectable particles, provided that the particles are bigger than ~10 nm and smaller than ~1 µm.

NTA vs DLS

Dynamic light scattering (DLS) is a similar technique that measures scattered light from a laser to determine particle sizes in solution. The key difference is that DLS takes a snapshot of the sample, meaning that all of the particles are measured at the same time. This makes it faster than NTA for characterizing a solution and determining the average particle size, making DLS more appropriate for monodisperse samples. This also makes DLS more suitable for measuring larger nanoparticles than NTA.

NTA, on the other hand, is more suitable for characterizing polydisperse samples and gathering size-distribution information. Ultimately, both methods have complementary attributes and can sometimes be used in conjunction to gather a full set of data.