Nanoparticle Characterization by Tracking

Particles present in samples were analysed by nanoparticle tracking, using the NanoSight LM10 system (NanoSight Ltd, Amesbury, UK), configured with a 405 nm laser and a high-sensitivity sCMOS camera (OrcaFlash2.8, Hamamatsu C11440, NanoSight Ltd). Videos were collected and analysed using the NTA software (version 2.3, build 0025), with the minimal expected particle size, minimum track length and blur setting, all set to automatic. Ambient temperature was recorded manually and did not exceed 25°C. Each sample was diluted in particle-free PBS and had a final volume of 0.4 ml. Samples were analysed within 15 min of the initial dilution with a delay of 10 seconds between sample introduction and the start of the measurement (16 ). Approximately 20–40 particles were in the field of view and the typical concentration was approximately 2×10⁸–10×10⁸ particles/ml for each measurement to keep within the linear range (14 (link)). For each sample, multiple videos of 60 seconds duration were recorded generating replicate histograms that were averaged. The typical number of completed and tracked events per measurements typically exceeded 2000, and 5 measurements taken per sample.