Bipolar Corona Discharge-Based Charge Equilibration for Nano Electrospray Gas-Phase Electrophoretic Mobility Molecular Analysis of Bio- and Polymer Nanoparticles

• Published in: Analytical chemistry (Washington) 2020-07, Vol.92 (13), p.8665-8669
• Main Authors: Weiss, Victor U, Frank, Johannes, Piplits, Kurt, Szymanski, Wladyslaw W, Allmaier, Günter
• Format: Article
• Language: English
• Subjects: Adapters; Balancing; Chemistry; Drying; Electric corona; Electric fields; Electrophoresis; Electrophoretic mobility; Electrospraying; Emitters; Laminar flow; Letter; Mobility; Nanoparticles; Polonium; Polymers; Proteins; Radioactive materials; Sheaths; Virus-like particles; Viruses; Waste disposal
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.0c01904

Separation of polydisperse, single-charged analytes in the nanometer size range in a high laminar sheath flow of particle-free ambient air and a tunable electric field based on the respective particle electrophoretic mobility diameter (EMD) can be achieved via gas-phase electrophoresis. In order to transfer analytes from a volatile electrolyte solution to the gas-phase as a single-charged species, a nano electrospray (nES) process followed by drying of nanodroplets and charge conditioning reaching Boltzmann charge equilibrium is a necessary prerequisite. In the case of a so-called nES gas-phase electrophoretic mobility molecular analyzer (nES GEMMA, also known as nES differential mobility analyzer, nES DMA), charge equilibration is based on bionanoparticle interaction with a bipolar atmosphere induced, e.g., by a radioactive α-particle emitter like 210Po. It was the aim of our investigation to examine whether such a radioactive source can be easily replaced in the same nES housing by a nonradioactive one, i.e., by an AC corona discharge unit. The latter would be significantly easier to handle when compared to radioactive material in laboratory day-to-day business, waste disposal, as well as regulatory confinements. Indeed, we were able to combine a standard nES unit of our nES GEMMA instrument with a commercially available AC corona discharge device in a novel setup via an adapter. Our results show that this replacement yields very good results for a number of chemically different nanoparticles, an exemplary protein, a noncovalent protein complex, a virus-like particle, a polymer, and a liposome sample, when compared to a 210Po based bipolar charge equilibration device.