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Characterization of M1 and M2 polarization phenotypes in peritoneal macrophages after treatment with graphene oxide nanosheets
摘要： Macrophages play a key role in nanoparticle removal and are primarily responsible for their uptake and trafficking in vivo. Due to their functional plasticity, macrophages display a spectrum of phenotypes between two extremes identified as pro-inflammatory M1 and reparative M2 macrophages, characterized by the expression of specific cell surface markers and the secretion of different cytokines. The influence of graphene oxide (GO) nanosheets functionalized with poly(ethylene glycol-amine) and labelled with fluorescein isothiocyanate (FITC-PEG-GO) on polarization of murine peritoneal macrophages towards M1 and M2 phenotypes was evaluated in basal and stimulated conditions by flow cytometry and confocal microscopy through the expression of different cell markers: CD80 and iNOS as M1 markers, and CD206 and CD163 as M2 markers. Although FITC-PEG-GO did not induce M1 or M2 macrophage polarization after 24 and 48 h in basal conditions, this nanomaterial decreased the percentage of M2 reparative macrophages. We have also compared control macrophages with macrophages that have or have not taken up FITC-PEG-GO after treatment with these nanosheets (GO+ and GO- cells, respectively). The CD80 expression diminished in GO+ macrophages after 48 h of GO treatment but the CD206 expression in GO+ population showed higher values than in both GO- population and control macrophages. In the presence of pro-inflammatory stimuli (LPS and IFN-γ), a significant decrease of CD80+ cells was observed after treatment with GO. This nanomaterial also induced significant decreases of CD206+ and CD163+ cells in the presence of reparative stimulus (IL-4). The CD80, iNOS and CD206 expression was lower in both GO- and GO+ cells than in control macrophages. However, higher CD163 expression was obtained in both GO- and GO+ cells in comparison with control macrophages. All these facts suggest that FITC-PEG-GO uptake did not induce the macrophage polarization towards the M1 pro-inflammatory phenotype, promoting the control of the M1/M2 balance with a slight shift towards M2 reparative phenotype involved in tissue repair, ensuring an appropriate immune response to these nanosheets.
关键词： Graphene oxide nanosheets,Macrophage polarization,Peritoneal macrophages,Cytokine profiling
更新于2025-09-23 15:23:52
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Synthesis of Graphene Oxide Nanosheets via Modified Hummers’ Method and Its Physicochemical Properties
摘要： The efficient synthesis of exfoliated graphene oxide nanosheets (GO) via modified Hummers’ method was successfully carried out. The physicochemical properties of GO were determined by Fourier transform infrared spectroscopy (FTIR), UV-visible spectrophotometry (UV-vis), x-ray diffraction analysis (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The graphite was fully oxidized by strong oxidizing agent caused the oxygen-containing functional groups such as C-O-C, C=O, and COOH were introduced into the graphite layers as analyzed by Raman and FTIR. XRD pattern of GO showed 2θ of 12.0o with interlayer spacing ~ 7.37A which describe non uniform crystal structure with the addition of oxygen containing functional groups. UV-vis spectrum of GO exhibit maximum absorption peak at ~ 234 nm corresponding to the aromatic C=C bond with π-π* transition. The morphology of GO was observed to have flake-like shape and less transparent layers by TEM. The properties of synthesized GO suggest high potential in producing the high quality of graphene which is can be applied as the electrocatalyst support for direct methanol fuel cell application.
关键词： Graphene oxide nanosheets,characterization,Hummers’ method,graphite,chemical oxidation
更新于2025-09-23 15:22:29
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Manipulated interparticle gaps of silver nanoparticles by dendron-exfoliated reduced graphene oxide nanohybrids for SERS detection
摘要： We have successfully prepared a floating-typed surface-enhanced Raman scattering (SERS) substrate by the uniform nanoparticle arrays of silver nanoparticles (AgNPs) immobilized on the dendron-exfoliated reduced graphene oxide (rGO) nanosheets. These poly(urea/malonamide) dendrons were precisely synthesized, and then grafted on the dendron-exfoliated rGO nanosheets based on an efficient building block of dual functional 4-isocyanato-4′-(3,3-dimethyl-2,4-dioxo-azetidino)-diphenylmethane (IDD). By using dendron-rGO nanosheets as templates for hosting AgNPs, the particle size (D) and interparticle gap (W) of AgNPs could be manipulated by the incorporation of dendrons of various generations (0.5, 1.5, and 2.5 generations), evaluated by transmission electron microscopy. The results indicate that the nanohybrids with 1.5 generation-dendron exhibited stable, enormous, and linear-quantitative Raman enhancement in malachite green detection (1–100 ppm), due to the lowest W/D ratio (0.85 ± 0.60) and interparticle gap (7.60 ± 5.29 nm). The limit of detection (LOD) of malachite green is lower than 2.7 × 10?11 M (0.01 ppb). AgNPs@rGO-dendritic derivative nanohybrids as floating and flexible SERS substrates provide ultrasensitive and stable SERS detection in the solutions, which offers great potential for practical applications in detecting environmental pollutants.
关键词： Silver nanoparticles,Reduced graphene oxide nanosheets,Surface-enhanced Raman scattering detection,Dendritic polymers
更新于2025-09-11 14:15:04