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Cellular imaging of endosome entrapped small gold nanoparticles.

Kim CS, Li X, Jiang Y, Yan B, Tonga GY, Ray M, Solfiell DJ, Rotello VM - MethodsX (2015)

Bottom Line: Information about the amount and location of sAuNPs in cells and tissues is critical to many applications.Here we use confocal laser scanning microscopy to provide endosome-entrapped sAuNP distributions and to quantify particle uptake into cells.The quantitative capabilities of the system were confirmed by inductively coupled plasma-mass spectrometry, with an observed linear relation between scattering intensity and the initial cellular uptake of sAuNPs using 4 nm and 6 nm core particles.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003, USA.

ABSTRACT
Small gold nanoparticles (sAuNPs, <10 nm in a core diameter) have been used for drug delivery and cancer therapy due to their high payload to carrier ratio. Information about the amount and location of sAuNPs in cells and tissues is critical to many applications. However, the current detection method (i.e., transmission electron microscopy) for such sAuNPs is limited due to the extensive sample preparation and the limited field of view. Here we use confocal laser scanning microscopy to provide endosome-entrapped sAuNP distributions and to quantify particle uptake into cells. The quantitative capabilities of the system were confirmed by inductively coupled plasma-mass spectrometry, with an observed linear relation between scattering intensity and the initial cellular uptake of sAuNPs using 4 nm and 6 nm core particles. The summary of the method is: •This non-invasive imaging strategy provides a tool for label-free real-time tracking and quantification of sAuNPs using a commercially available confocal laser scanning microscope.•Scattering intensity depends on particle size.•The linear relation established between scattering intensity and uptaken gold amount enables simultaneous quantitative assessment through simple image analysis.

No MeSH data available.


CLSM images of different-sized AuNPs acquired after 3 h incubation in HeLa cells. The scattering images (a, c, and e) and corresponding merged images with bright-field images (b, d, and f) represent incubation with 2-nm (200 nM), 4-nm (100 nM), and 6-nm (30 nM) AuNPs, respectively. Scale bar is 50 μm. (For interpretation of the references to color in text, the reader is referred to the web version of this article.)
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fig0010: CLSM images of different-sized AuNPs acquired after 3 h incubation in HeLa cells. The scattering images (a, c, and e) and corresponding merged images with bright-field images (b, d, and f) represent incubation with 2-nm (200 nM), 4-nm (100 nM), and 6-nm (30 nM) AuNPs, respectively. Scale bar is 50 μm. (For interpretation of the references to color in text, the reader is referred to the web version of this article.)

Mentions: HeLa cells were prepared and incubated with the different-sized sAuNPs for 3 h and then washed three times with phosphate-buffered saline (PBS) to remove free sAuNPs from the cell medium before imaging. The images were collected by using CLSM at 514 nm. Cells without AuNPs were used as a control to adjust the detector gain and establish the baseline. As shown in Fig. 2, scattering signals were observed from 6- and 4-nm AuNPs (marked in green) after being dramatically uptaken by the cells. Whereas no signals were detected from 2-nm AuNPs even at the highest concentration of 200 nM. These images reveal that the scattering imaging intensity of sAuNPs is size dependent. Both 4- and 6-nm AuNPs were clearly visualized inside cells due to the high enrichment of the cells with both the particles. Therefore, the 4- and 6-nm AuNPs were used in the following studies. Lysotracker was used and confirmed that the uptaken AuNPs (4 and 6 nm) were partially localized in the late endosome/lysosome at this point (Fig. S3).


Cellular imaging of endosome entrapped small gold nanoparticles.

Kim CS, Li X, Jiang Y, Yan B, Tonga GY, Ray M, Solfiell DJ, Rotello VM - MethodsX (2015)

CLSM images of different-sized AuNPs acquired after 3 h incubation in HeLa cells. The scattering images (a, c, and e) and corresponding merged images with bright-field images (b, d, and f) represent incubation with 2-nm (200 nM), 4-nm (100 nM), and 6-nm (30 nM) AuNPs, respectively. Scale bar is 50 μm. (For interpretation of the references to color in text, the reader is referred to the web version of this article.)
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4487928&req=5

fig0010: CLSM images of different-sized AuNPs acquired after 3 h incubation in HeLa cells. The scattering images (a, c, and e) and corresponding merged images with bright-field images (b, d, and f) represent incubation with 2-nm (200 nM), 4-nm (100 nM), and 6-nm (30 nM) AuNPs, respectively. Scale bar is 50 μm. (For interpretation of the references to color in text, the reader is referred to the web version of this article.)
Mentions: HeLa cells were prepared and incubated with the different-sized sAuNPs for 3 h and then washed three times with phosphate-buffered saline (PBS) to remove free sAuNPs from the cell medium before imaging. The images were collected by using CLSM at 514 nm. Cells without AuNPs were used as a control to adjust the detector gain and establish the baseline. As shown in Fig. 2, scattering signals were observed from 6- and 4-nm AuNPs (marked in green) after being dramatically uptaken by the cells. Whereas no signals were detected from 2-nm AuNPs even at the highest concentration of 200 nM. These images reveal that the scattering imaging intensity of sAuNPs is size dependent. Both 4- and 6-nm AuNPs were clearly visualized inside cells due to the high enrichment of the cells with both the particles. Therefore, the 4- and 6-nm AuNPs were used in the following studies. Lysotracker was used and confirmed that the uptaken AuNPs (4 and 6 nm) were partially localized in the late endosome/lysosome at this point (Fig. S3).

Bottom Line: Information about the amount and location of sAuNPs in cells and tissues is critical to many applications.Here we use confocal laser scanning microscopy to provide endosome-entrapped sAuNP distributions and to quantify particle uptake into cells.The quantitative capabilities of the system were confirmed by inductively coupled plasma-mass spectrometry, with an observed linear relation between scattering intensity and the initial cellular uptake of sAuNPs using 4 nm and 6 nm core particles.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Massachusetts Amherst, 710 North Pleasant Street, Amherst, MA 01003, USA.

ABSTRACT
Small gold nanoparticles (sAuNPs, <10 nm in a core diameter) have been used for drug delivery and cancer therapy due to their high payload to carrier ratio. Information about the amount and location of sAuNPs in cells and tissues is critical to many applications. However, the current detection method (i.e., transmission electron microscopy) for such sAuNPs is limited due to the extensive sample preparation and the limited field of view. Here we use confocal laser scanning microscopy to provide endosome-entrapped sAuNP distributions and to quantify particle uptake into cells. The quantitative capabilities of the system were confirmed by inductively coupled plasma-mass spectrometry, with an observed linear relation between scattering intensity and the initial cellular uptake of sAuNPs using 4 nm and 6 nm core particles. The summary of the method is: •This non-invasive imaging strategy provides a tool for label-free real-time tracking and quantification of sAuNPs using a commercially available confocal laser scanning microscope.•Scattering intensity depends on particle size.•The linear relation established between scattering intensity and uptaken gold amount enables simultaneous quantitative assessment through simple image analysis.

No MeSH data available.