Abstract
The development of reliable protocols suitable for the characterisation of the physical properties of nanoparticles in suspension is becoming crucial to assess the potential biological as well as toxicological impact of nanoparticles. Amongst sizing techniques, asymmetric flow field flow fractionation (AF4) coupled to online size detectors represents one of the most robust and flexible options to quantify the particle size distribution in suspension. However, size measurement uncertainties have been reported for on-line dynamic light scattering (DLS) detectors when coupled to AF4 systems. In this work we investigated the influence of the initial concentration of nanoparticles in suspension on the sizing capability of the asymmetric flow field-flow fractionation technique coupled with an on-line dynamic light scattering detector and a UV–Visible spectrophotometer (UV) detector. Experiments were performed with suspensions of gold nanoparticles with a nominal diameter of 40 nm and 60 nm at a range of particle concentrations. The results obtained demonstrate that at low concentration of nanoparticles, the AF4-DLS combined technique fails to evaluate the real size of nanoparticles in suspension, detecting an apparent and progressive size increase as a function of the elution time and of the concentration of nanoparticles in suspension.
Highlights
Asymmetric flow field flow fractionation (AF4) is a liquidbased fractionation technique which is commonly used in the separation and characterization of particle, polymer and protein suspensions
We investigated the influence of the initial concentration of nanoparticles in suspension on the sizing ability of an AF4-dynamic light scattering (DLS)-UV–Visible spectrophotometer (UV) system, by testing suspensions of gold nanoparticles with a known nominal diameter of 40 nm and 60 nm
At the higher initial concentration of 1 011 particles mL−1, the AF4-DLS-UV system provides an accurate sizing of the nanoparticles in suspension returning an average diameter close to the nominal one with low coefficients of variation throughout all the zones identified in the absorbance distribution curves
Summary
Asymmetric flow field flow fractionation (AF4) is a liquidbased fractionation technique which is commonly used in the separation and characterization of particle, polymer and protein suspensions. Some studies in the literature suggest that the apparent progressive size increase detected by the DLS at low concentrations of particles (at the beginning and at the end of the absorbance distribution curve) can be related to the presence of larger aggregates in suspension.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
