Sizing Nanomatter in Biological Fluids by Fluorescence Single Particle Tracking

Abstract

Accurate sizing of nanoparticles in biological media is important for drug delivery and biomedical imaging applications since size directly influences the nanoparticle processing and nanotoxicity in vivo. Using fluorescence single particle tracking we have succeeded for the first time in following the aggregation of drug delivery nanoparticles in real time in undiluted whole blood. We demonstrate that, by using a suitable surface functionalization, nanoparticle aggregation in the blood circulation is prevented to a large extent.

On-chip light sheet illumination enables diagnostic size and concentration measurements of membrane vesicles in biofluids

“…This leads to a distribution of diffusion coefficients when many particles are analysed. A maximum entropy deconvolution step can subsequently be applied to this distribution to reduce sampling noise and improve its precision 11 . The distribution of diffusion coefficients can be converted to a size distribution via the Stokes-Einstein relation.…”

“…Specifically, due to a lack of standardized isolation and purification protocols and in order to avoid manipulation artefacts, techniques capable of performing MV characterization directly in body fluids are urgently needed 2,9,10 . Fluorescence Single Particle Tracking (fSPT) was recently shown to be the first technique capable of accurately measuring the size distribution and number concentration of fluorescently labelled nanoparticles in undiluted biofluids, such as whole blood 11,12 . However, being based on epi-fluorescence microscopy, a limitation of the technique is limited contrast due to fluorescence coming from out-of-focus particles or unbound fluorescent dye, as illustrated in Figure 1a.…”

Hybrid pulmonary surfactant-coated nanogels mediate efficient in vivo delivery of siRNA to murine alveolar macrophages

“…Nanoparticle concentration determined by fluorescence single particle tracking Fluorescence single particle tracking (fSPT) is a technique that monitors the diffusional movement of individual fluorescently labeled nanoparticles using a highly sensitive fluorescence microscope setup as described in [25]. Besides the size of nanoparticles, this technique also allows to accurately measure the absolute number concentrations of nanoparticles dispersed in complex biological fluids [26].…”

“…A fast and sensitive EMCCD camera (Ixon Ultra 897; Andor Technology, South Windsor, USA) recorded high-speed movies of the individual particles diffusing in the dispersion. Particle trajectories were subsequently calculated using inhouse developed software [25]. In this work, the technique was used to simultaneously determine the concentration of fluorescently-labeled siNGs and empty pulmonary surfactant present in the surfactant-coated siNG dispersion, before and after purification.…”

“…As described earlier, this technique allows accurate quantification of absolute number concentrations of fluorescently labeled nanoparticles in complex mixtures [25,26]. To distinguish both particle types, Curosurf ® was fluorescently labeled by insertion of the green fluorescent lipid-like dye DiO, while NGs were loaded with red fluorescent siRNA (siCy5).…”