Measuring Nanoparticle Polarizability Using Fluorescence Microscopy

• DOI: 10.1021/acs.nanolett.9b02402
• Publication Date: 2019-07-16T10:03:32Z
• Authors: Wenhan Cao; Margaret Chern; Allison M. Dennis; Keith A. Brown
• Keywords: Electricity; Microscopy, Fluorescence; Quantum Dots; Static Electricity; Electric Conductivity; Particle Size; 01 natural sciences; 0104 chemical sciences

Using a novel method developed to quantify the polarizability of photoluminescent nanoparticles in water, we present experimental observations extraordinary exhibited by commensurate size with Debye screening length, confirming previously reported theory. Semiconductor quantum dots (QDs) are ideal model demonstrate this assay, due their tunable and bright photoluminescence. This assay is based upon microfluidic chambers microelectrodes that generate trapping potentials weaker than thermal energy. By comparing local electric field strength variations QD concentration, was computed found agree estimates hydrodynamic diameter using light scattering. Strikingly, increased 30-fold low salt conditions compared high thickness layer relative particle radius. In addition providing evidence corroborates theoretical work studying direct solutions Poisson-Nernst-Planck equations, these provide an explanation for observed conductivity dependence biomolecule polarizability. As importance electrically directed assembly particles, as well interactions other materials complex environments, anticipate results will be highly relevant ongoing efforts design nanomedicine.