Surface characterization of nanoparticles using near-field light scattering

Abstract

The effect of nanoparticle surface coating characteristics on colloidal stability in solution is a critical parameter in understanding the potential applications of nanoparticles, especially in biomedicine. Here we explored the modification of the surface of poly(ethylene glycol)-coated superparamagnetic iron oxide nanoparticles (PEG-SPIOs) with the synthetic pseudotannin polygallol via interpolymer complexation (IPC). Changes in particle size and zeta potential were indirectly assessed via differences between PEG-SPIOs and IPC-SPIOs in particle velocity and scattering intensity using near-field light scattering. The local scattering intensity is correlated with the distance between the particle and waveguide, which is affected by the size of the particle (coating thickness) as well as the interactions between the particle and waveguide (related to the zeta potential of the coating). Therefore, we report here the use of near-field light scattering using nanophotonic force microscopy (using a NanoTweezerTM instrument, Halo Labs) to determine the changes that occurred in hydrated particle characteristics, which is accompanied by an analytical model. Furthermore, we found that altering the salt concentration of the suspension solution affected the velocity of particles due to the change of dielectric constant and viscosity of the solution. These findings suggest that this technique is suitable for studying particle surface changes and perhaps can be used to dynamically study reaction kinetics at the particle surface.

Improvement of N-Acetylcysteine Loaded in PLGA Nanoparticles by Nanoprecipitation Method

“…ese results differ from values obtained by DLS (235.5 ± 11.4 nm). It could be explained by the fact that TEM samples were dried as a preparation for TEM imaging, while DLS reported the hydrodynamic diameter that includes core plus any molecule attached on surface; this kind of difference between these techniques had been reported by other researchers [49,50]. e nanoparticle zeta potential was −3.42 ± 0.5 mV, the entrapment efficiency was 0.4 ± 0.04%, and the specific load was 3.14 ± 0.33%.…”

Activatable superparamagnetic iron oxide nanoparticles scavenge reactive oxygen species in macrophages and endothelial cells

“…Briey, uncoated SPIOs were synthesized via the coprecipitation method under N 2 atmosphere and vigorous magnetic stirring from a mixture of FeCl 2 (Sigma) and FeCl 3 (Sigma) in DI water. 43,44 The mixture was heated to 80 C, and ammonium hydroxide (NH 4 OH) (BDH; Poole, Dorset, UK) was added dropwise and allowed to stir for 5 hours to complete the reaction. Uncoated SPIOs were puried and collected via magnetic decantation and centrifugation.…”

“…The synthesis and characterization of IPC-SPIOs was published previously and is summarized here. 43,44 Briey, transmission electron microscope (TEM) scans of uncoated SPIOs showed spherically shaped particles, and PEG SPIOs had gray halo around the much darker SPIO nanoparticles, demonstrating the polymer coating was present. The presence of iron and oxygen was validated using energy dispersive X-ray spectroscopy (EDS).…”

“…Nanoparticles had an external spherical morphology with an average diameter slightly larger than TEM scans. 43,44 IPC-SPIOs are not suitable for TEM or SEM imaging as polymer coatings continued to degrade under the electron beam. Here, we characterized the hydrodynamic size, zeta potential, and polydispersity index of all nanoparticle formulations with DLS before use.…”

Development and characterization of phytosterol nanoemulsions and self-microemulsifying drug delivery systems

“…The particle size, polydispersity index (PDI) and Zeta potential of the microemulsion were measured. All samples were balanced for 120s at 25 °C before measurement and each sample was measured three times in parallel with Zetasizer Nano S90 High Sensitivity Nano Particle Size Analyzer (UK Malvern Instruments Co., Ltd.) [22]. SM 25.00 mg in 10 ml volume bottle was shaken with methanol until calibration,ultrasound was performed for 10 minutes, concentration was determined by HPLC and recorded as W1 [23] .100.00 mg SM in 5 ml volume bottle was shaken with distilled water to scale.…”