Characterization, detection, and counting of metal nanoparticles using flow cytometry

Abstract

There is a need to accurately detect, characterize, and quantify nanoparticles in suspensions. This study helps to understand the complex interactions between similar types of nanoparticles. Before initiating a study of metal nanoparticles, five submicron PS beads with sizes between 200 nm and 1 mm were used to derive a reference scale that was useful in evaluating the flow cytometer for functionality, sensitivity, resolution, and reproducibility. Side scatter intensity (SSC) from metal nanoparticles was obtained simultaneously from 405 nm and 488 nm lasers. The 405 nm laser generally yielded histogram distributions with smaller CVs, less side scatter intensity, better separation indices between beads and decreased scatter differences between different sized particles compared with the 488 nm laser. Submicron particles must be diluted to 10 6 and 10 7 particles/mL before flow cytometer analysis to avoid coincidence counting artifacts. When particles were too concentrated the following occurred: swarm, electronic overload, coincidence counting, activation of doublet discrimination and rejection circuitry, increase of mean SSC histogram distributions, alterations of SSC and pulse width histogram shape, decrease and fluctuations in counting rate and decrease or elimination of particulate water noise and 1 mm reference bead. To insure that the concentrations were in the proper counting range, the nanoparticle samples were mixed with a known concentration of 1mm counting beads. Sequential dilutions of metal nanoparticles in a 1 mm counting bead suspension helped determine the diluted concentration needed for flow cytometer analysis. It was found that the original concentrated nanoparticle samples had to be diluted, between 1:10,000 and 1:100,000, before characterization by flow cytometry. The concentration of silver or gold nanoparticles in the undiluted sample were determined by comparing them with a known concentration (1.9 3 10 6 beads/mL) of 1 mm polystyrene reference beads. Published 2015 Wiley Periodicals Inc., on behalf of ISAC

Nanobubble Mediated Gene Delivery in Conjunction With a Hand-Held Ultrasound Scanner

“…nanoscale particles). In order to relate Violet-SS to a particle size, we calibrated the flow cytometer with beads of known size (Wisgrill et al, 2016;Zucker et al, 2016). The polystyrene standard beads (200, 350, and 800 nm; qNano Calibration Particles; Izon Science, Christchurch, New Zealand, 500 and 1000 nm; Archimedes Standard polystyrene beads; Malvern Instruments, Worcestershire, UK) was suspended in ultrapure water and measured beforehand with the flow cytometer.…”

Unique Calibrators Derived from Fluorescence‐Activated Nanoparticle Sorting for Flow Cytometric Size Estimation of Artificial Vesicles: Possibilities and Limitations

“…A few studies have employed flow cytometry to study nanoparticles made of polystyrene, silica, titanium dioxide, gold, or silver (1)(2)(3). A few studies have employed flow cytometry to study nanoparticles made of polystyrene, silica, titanium dioxide, gold, or silver (1)(2)(3).…”

“…Only recently has the ability of flow cytometry been explored and exploited to also include the characterization of nanoparticles. A few studies have employed flow cytometry to study nanoparticles made of polystyrene, silica, titanium dioxide, gold, or silver (1)(2)(3). Artificial vesicles (liposomes) have also been studied (4)(5)(6)(7)(8), but the focus has largely been on assessing the enumeration, surface antigens, and size distributions of biological nano-sized vesicles known as extracellular vesicles (EVs) (8)(9)(10)(11)(12)(13)(14)(15).…”

Characterization and function of medium and large extracellular vesicles from plasma and urine by surface antigens and Annexin V

“…A previous report suggested that flow cytometry side-scatter values were suitable for observation of EVs less than 1000 nm in diameter, and in our study m/lEV size was measured by comparison with polystyrene beads [23,24]. Based on the results of NTA analysis, small materials ≤100 nm in diameter are included in fractions isolated by centrifugation.…”