Abstract
Functional coatings based on the assembly of submicrometric or nanoparticles are found in many applications in the biomedical field. However, these nanoparticle-based coatings are particularly fragile since they could be exposed to cells that are able to internalize nanoparticles. Here, we studied the efficiency of RAW 264.7 murine macrophages to internalize physisorbed silica nanoparticles as a function of time and particle size. This cell internalization efficiency was evaluated from the damages induced by the cells in the nanoparticle-based monolayer on the basis of scanning electron microscopy and confocal laser scanning microscopy observations. The internalization efficiency in terms of the percentage of nanoparticles cleared from the substrate is characterized by two size-dependent regimes. Additionally, we highlighted that a delay before internalization occurs, which increases with decreasing adsorbed nanoparticle size. This internalization is characterized by a minimal threshold that corresponds to 35 nm nanoparticles that are not internalized during the 12-h incubation considered in this work.
Highlights
Functional coatings based on the assembly of submicrometric or nanometric particles (NPs) are found in many applications in biomedical field
We prepared model surfaces consisting of monolayers of fluorescent silica nanoparticles (NPs) adsorbed on silicon wafers
Based on scanning electron microscopy observations (SEM) observations, particle internalization by cells from the monolayers was analyzed at short incubation times (1 h, 3 h, 6 h, 9 h and 12 h) and for six different particle sizes (450 nm, 300 nm, 200 nm, 100 nm, 50 nm and 35 nm)
Summary
Functional coatings based on the assembly of submicrometric or nanometric particles (NPs) are found in many applications in biomedical field. NPs-based coatings are fragile and often need to be reinforced before use, for example, by hydrothermal treatments [7,8] or atomic layer deposition [9] In this context, it is important to quantify their mechanical properties, especially their resistance to friction. As central actors of the early immune response, macrophages are likely to be recruited on site soon after implementation During their migration, these cells might develop interactions with the biomaterial surface and try to internalize the NPs. During their migration, these cells might develop interactions with the biomaterial surface and try to internalize the NPs These interaction forces, which can be as high as a few micronewtons [11,12,13], can damage the coatings by removing or internalizing physisorbed NPs, leading to inflammation or dispersion of NPs in the body.
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