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Spontaneous confocal Raman microscopy--a tool to study the uptake of nanoparticles and carbon nanotubes into cells.

Romero G, Rojas E, Estrela-Lopis I, Donath E, Moya SE - Nanoscale Res Lett (2011)

Bottom Line: Confocal Raman microscopy as a label-free technique was applied to study the uptake and internalization of poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) and carbon nanotubes (CNTs) into hepatocarcinoma human HepG2 cells.Spontaneous confocal Raman spectra was recorded from the cells exposed to oxidized CNTs and to PLGA NPs.For PLGA NPs, it was found that they preferentially co-localized with lipid bodies, while the oxidized CNTs are located in the cytoplasm.

View Article: PubMed Central - HTML - PubMed

Affiliation: CIC biomaGUNE, Paseo Miramón 182 C, 20009 San Sebastian, Spain. smoya@cicbiomagune.es.

ABSTRACT
Confocal Raman microscopy as a label-free technique was applied to study the uptake and internalization of poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) and carbon nanotubes (CNTs) into hepatocarcinoma human HepG2 cells. Spontaneous confocal Raman spectra was recorded from the cells exposed to oxidized CNTs and to PLGA NPs. The Raman spectra showed bands arising from the cellular environment: lipids, proteins, nucleic acids, as well as bands characteristic for either PLGA NPs or CNTs. The simultaneous generation of Raman bands from the cell and nanomaterials from the same spot proves internalization, and also indicates the cellular region, where the nanomaterial is located. For PLGA NPs, it was found that they preferentially co-localized with lipid bodies, while the oxidized CNTs are located in the cytoplasm.

No MeSH data available.


Related in: MedlinePlus

Raman spectra of CNTs and Raman imaging of cells exposed to CNTs. (a) Spectra of oxidized CNTs (green), free cell in the region of the LB (pink) and cell exposed to CNTs at the same region (blue). (b) Raman spectra taken in one spot at different planes at a HepG2 cell treated with oxidized CNTs. The insets correspond to the image of the cell under study.
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Figure 3: Raman spectra of CNTs and Raman imaging of cells exposed to CNTs. (a) Spectra of oxidized CNTs (green), free cell in the region of the LB (pink) and cell exposed to CNTs at the same region (blue). (b) Raman spectra taken in one spot at different planes at a HepG2 cell treated with oxidized CNTs. The insets correspond to the image of the cell under study.

Mentions: Similar uptake experiments were performed with oxidized CNTs. The CNTs were oxidized to provide them with charges to ensure their stabilization in aqueous solution. In Figure 3a, we can observe the Raman spectrum of oxidized CNTs and HepG2 cells exposed to the CNTs. CNTs show characteristic bands at 1350 cm-1 (D-band) and 1585 cm-1 (G-band) [10,11]. The D-band is an indicator for disorder in the graphene sheet and is called ''disorder-induced" band. The G-band is a tangential mode originating from tangential oscillations of the carbon atoms in the CNTs. These bands can be clearly observed in the cellular spectra. Scans were performed at different planes within the cells as shown in Figure 3b. The plane denoted by 0 μm corresponds to the situation, where the signals of the D and G bands from the CNTs were the strongest. Then, spectra were recorded at higher and lower planes, respectively. In all cases, the CNTs spectral signature was parallelled by CH3-stretching modes, typical for proteins. The CH2 stretching, which is indicative for LB, can be barely seen. The intensity of the CNTs bands varied considerably over the different scan planes. From these findings, we draw the conclusion that the CNTs are not homogeneously distributed in the cytoplasm, nor they are closely associated with LB. Furthermore, the z-scanning provides an unambiguous proof of internalization of the NPs, since we move in distances of micrometers inside the cell, where the detection of CNTs attached to the cell membrane from the outside is very unlikely.


Spontaneous confocal Raman microscopy--a tool to study the uptake of nanoparticles and carbon nanotubes into cells.

Romero G, Rojas E, Estrela-Lopis I, Donath E, Moya SE - Nanoscale Res Lett (2011)

Raman spectra of CNTs and Raman imaging of cells exposed to CNTs. (a) Spectra of oxidized CNTs (green), free cell in the region of the LB (pink) and cell exposed to CNTs at the same region (blue). (b) Raman spectra taken in one spot at different planes at a HepG2 cell treated with oxidized CNTs. The insets correspond to the image of the cell under study.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC3211846&req=5

Figure 3: Raman spectra of CNTs and Raman imaging of cells exposed to CNTs. (a) Spectra of oxidized CNTs (green), free cell in the region of the LB (pink) and cell exposed to CNTs at the same region (blue). (b) Raman spectra taken in one spot at different planes at a HepG2 cell treated with oxidized CNTs. The insets correspond to the image of the cell under study.
Mentions: Similar uptake experiments were performed with oxidized CNTs. The CNTs were oxidized to provide them with charges to ensure their stabilization in aqueous solution. In Figure 3a, we can observe the Raman spectrum of oxidized CNTs and HepG2 cells exposed to the CNTs. CNTs show characteristic bands at 1350 cm-1 (D-band) and 1585 cm-1 (G-band) [10,11]. The D-band is an indicator for disorder in the graphene sheet and is called ''disorder-induced" band. The G-band is a tangential mode originating from tangential oscillations of the carbon atoms in the CNTs. These bands can be clearly observed in the cellular spectra. Scans were performed at different planes within the cells as shown in Figure 3b. The plane denoted by 0 μm corresponds to the situation, where the signals of the D and G bands from the CNTs were the strongest. Then, spectra were recorded at higher and lower planes, respectively. In all cases, the CNTs spectral signature was parallelled by CH3-stretching modes, typical for proteins. The CH2 stretching, which is indicative for LB, can be barely seen. The intensity of the CNTs bands varied considerably over the different scan planes. From these findings, we draw the conclusion that the CNTs are not homogeneously distributed in the cytoplasm, nor they are closely associated with LB. Furthermore, the z-scanning provides an unambiguous proof of internalization of the NPs, since we move in distances of micrometers inside the cell, where the detection of CNTs attached to the cell membrane from the outside is very unlikely.

Bottom Line: Confocal Raman microscopy as a label-free technique was applied to study the uptake and internalization of poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) and carbon nanotubes (CNTs) into hepatocarcinoma human HepG2 cells.Spontaneous confocal Raman spectra was recorded from the cells exposed to oxidized CNTs and to PLGA NPs.For PLGA NPs, it was found that they preferentially co-localized with lipid bodies, while the oxidized CNTs are located in the cytoplasm.

View Article: PubMed Central - HTML - PubMed

Affiliation: CIC biomaGUNE, Paseo Miramón 182 C, 20009 San Sebastian, Spain. smoya@cicbiomagune.es.

ABSTRACT
Confocal Raman microscopy as a label-free technique was applied to study the uptake and internalization of poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) and carbon nanotubes (CNTs) into hepatocarcinoma human HepG2 cells. Spontaneous confocal Raman spectra was recorded from the cells exposed to oxidized CNTs and to PLGA NPs. The Raman spectra showed bands arising from the cellular environment: lipids, proteins, nucleic acids, as well as bands characteristic for either PLGA NPs or CNTs. The simultaneous generation of Raman bands from the cell and nanomaterials from the same spot proves internalization, and also indicates the cellular region, where the nanomaterial is located. For PLGA NPs, it was found that they preferentially co-localized with lipid bodies, while the oxidized CNTs are located in the cytoplasm.

No MeSH data available.


Related in: MedlinePlus