Characterization of Nanoparticles in Diverse Mixtures Using Localized Surface Plasmon Resonance and Nanoparticle Tracking by Dark-Field Microscopy with Redox Magnetohydrodynamics Microfluidics.

by Sikes, Jazlynn C.; Wonner, Kevin; Nicholson, Aaron; Cignoni, Paolo; Fritsch, Ingrid; Tschulik, Kristina

Redox MHDs (RMHD) microfluidics is coupled with dark-field microscopy (DFM) to offer high-throughput single-nanoparticle (NP) differentiation in situ and operando in a flowing mixt. by localized surface plasmon resonance (LSPR) and tracking of NPs. The color of the scattered light allows visualization of the NPs below the diffraction limit. Their Brownian motion in 1-D superimposed on and perpendicular to the RMHD trajectory yields their diffusion coeffs. LSPR and diffusion coeffs. provide two orthogonal modalities for characterization where each depends on a particle's material compn., shape, size, and interactions with the surrounding medium. RMHD coupled with DFM was demonstrated on a mixt. of 82 ± 9 nm silver and 140 ± 10 nm gold-coated silica nanospheres. The two populations of NPs in the mixt. were identified by blue/green and orange/red LSPR and their scattering intensity, resp., and their sizes were further evaluated based on their diffusion coeffs. RMHD microfluidics facilitates high-throughput anal. by moving the sample soln. across the wide field of view absent of phys. vibrations within the exptl. cell. The well-controlled pumping allows for a continuous, reversible, and uniform flow for precise and simultaneous NP tracking of the Brownian motion. Addnl., the amts. of nanomaterials required for the anal. are minimized due to the elimination of an inlet and outlet. Several hundred individual NPs were differentiated from each other in the mixt. flowing in forward and reverse directions. The ability to immediately reverse the flow direction also facilitates re-anal. of the NPs, enabling more precise sizing.

ACS Physical Chemistry Au
Start Page