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.
Highlights
Nanotechnology is an increasingly integral part of modern medicine, predominantly in the fields of cell labeling, gene and drug delivery, molecular imaging, and biosensors [1,2,3,4]
We present one potential application of near-field light scattering-based nanophotonic force microscopy used to evaluate changes in particle surface and size by examining the self-assembly of interpolymer complexed superparamagnetic iron oxide nanoparticles (IPC-SPIOs)
The uncoated SPIOs stuck to the waveguide and could not be analyzed further, while the light scattered from poly(ethylene glycol) (PEG)-SPIOs and interpolymer complexation (IPC)-SPIOs was imaged, as the laser pushed the trapped nanoparticles across the waveguide (Figure 4)
Summary
Nanotechnology is an increasingly integral part of modern medicine, predominantly in the fields of cell labeling, gene and drug delivery, molecular imaging, and biosensors [1,2,3,4]. We present one potential application of near-field light scattering-based nanophotonic force microscopy used to evaluate changes in particle surface and size by examining the self-assembly of interpolymer complexed superparamagnetic iron oxide nanoparticles (IPC-SPIOs).
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