Nanorods of Well-Defined Length and Monodisperse Cross-Section Obtained from Electrostatic Complexation of Nanoparticles with a Semiflexible Biopolymer

We show by combining small-angle X-ray scattering (SAXS) and cryo-transmission electron microscopy (cryo-TEM) that anionic silica nanoparticles (SiNPs) assemble into well-defined 1D cluster when mixed with a dilute solution of semiflexible chitosan polycation. The nanorods are stable in excess of SiNPs and composed of 10 SiNPs well-ordered into straight single strands with length Lrod approx 184.0 nm and radius Rrod = 9.2 nm = RSiNPs. We point out that the ratio between the chitosan persistence length and the SiNP radius, which is here equal to 1, can be the determining condition to obtain such original objects.