Characterization of i-colloid Nanoparticles by Dynamic Light Scattering (DLS) 

Dynamic Light Scattering (DLS) is not an accurate size measurement method for i-colloid nanoparticles but is a useful tool for assessing the outcome of conjugation reactions. IMRA performs DLS measurements using a Malvern Zeta-sizer Nano ZS-90 instrument equipped with 632.8 nm HeNe laser and 90 degree scattering detector.

Bare 20 nm and 40 nm (sized by disc centrifugation) i-colloid gold nanoparticles have slightly elliptical shapes, which are detected as both smaller and larger apparent sizes during rotational movement and result in a DLS intensity size distribution plot with two peaks. The smaller peak is < 10 nm, while the larger peak is greater than the size determined by disc centrifugation. Typical DLS profiles for i-colloid 20 nm and 40 nm gold are shown below.