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Biological Atomic Force Microscopy for Imaging Gold-Labeled Liposomes on Human Coronary Artery Endothelial Cells.

Zaske AM, Danila D, Queen MC, Golunski E, Conyers JL - J Pharm (Cairo) (2013)

Bottom Line: Dynasore monohydrate, an inhibitor of endocytosis, obstructed the internalization of the gold-liposomes.This study showed the versatility of the AFM technique, combined with fluorescent microscopy, for investigating liposome uptake by endothelial cells.The 90 nm colloidal gold nanoparticles proved to be a noninvasive contrast agent that efficiently improves AFM imaging during the investigation of biological nanoprocesses.

View Article: PubMed Central - PubMed

Affiliation: Division of Cardiology, Department of Internal Medicine, The University of Texas Health Science Center at Houston, 1881 East Road, Houston, TX 77054, USA.

ABSTRACT
Although atomic force microscopy (AFM) has been used extensively to characterize cell membrane structure and cellular processes such as endocytosis and exocytosis, the corrugated surface of the cell membrane hinders the visualization of extracellular entities, such as liposomes, that may interact with the cell. To overcome this barrier, we used 90 nm nanogold particles to label FITC liposomes and monitor their endocytosis on human coronary artery endothelial cells (HCAECs) in vitro. We were able to study the internalization process of gold-coupled liposomes on endothelial cells, by using AFM. We found that the gold-liposomes attached to the HCAEC cell membrane during the first 15-30 min of incubation, liposome cell internalization occurred from 30 to 60 min, and most of the gold-labeled liposomes had invaginated after 2 hr of incubation. Liposomal uptake took place most commonly at the periphery of the nuclear zone. Dynasore monohydrate, an inhibitor of endocytosis, obstructed the internalization of the gold-liposomes. This study showed the versatility of the AFM technique, combined with fluorescent microscopy, for investigating liposome uptake by endothelial cells. The 90 nm colloidal gold nanoparticles proved to be a noninvasive contrast agent that efficiently improves AFM imaging during the investigation of biological nanoprocesses.

No MeSH data available.


Related in: MedlinePlus

AFM images of FITC-labeled liposomes coupled to 90 nm gold particles and scanned on fresh cleaved mica. (a) Height image with section analysis measuring the diameter of three particles (95, 86, and 80 nm, resp.) that made up a typical gold-liposome cluster. (b) Additional digital zoom to 1 μm2 taken from the original scan at 2.5 μm (x-y). The DLS analysis showed that the gold-liposome complexes had a diameter of 285 ± 5.3 nm. Tapping mode in air using RTESP cantilevers (fo = 262–325 kHz, k = 20–80 N/m).
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fig3: AFM images of FITC-labeled liposomes coupled to 90 nm gold particles and scanned on fresh cleaved mica. (a) Height image with section analysis measuring the diameter of three particles (95, 86, and 80 nm, resp.) that made up a typical gold-liposome cluster. (b) Additional digital zoom to 1 μm2 taken from the original scan at 2.5 μm (x-y). The DLS analysis showed that the gold-liposome complexes had a diameter of 285 ± 5.3 nm. Tapping mode in air using RTESP cantilevers (fo = 262–325 kHz, k = 20–80 N/m).

Mentions: To enhance AFM imaging, nanogold particles were covalently linked to FITC liposomes. We choose 90 nm gold particles to facilitate visualization within the cell membrane taking into consideration that ~120 nm gold nanoparticles are normally used for thermal ablation. Figure 3 shows AFM imaging of the geometric structure of a typical gold-liposome cluster (303 nm in size) consisting of three distinctive particles with individual diameters of 95, 86, and 80 nm.


Biological Atomic Force Microscopy for Imaging Gold-Labeled Liposomes on Human Coronary Artery Endothelial Cells.

Zaske AM, Danila D, Queen MC, Golunski E, Conyers JL - J Pharm (Cairo) (2013)

AFM images of FITC-labeled liposomes coupled to 90 nm gold particles and scanned on fresh cleaved mica. (a) Height image with section analysis measuring the diameter of three particles (95, 86, and 80 nm, resp.) that made up a typical gold-liposome cluster. (b) Additional digital zoom to 1 μm2 taken from the original scan at 2.5 μm (x-y). The DLS analysis showed that the gold-liposome complexes had a diameter of 285 ± 5.3 nm. Tapping mode in air using RTESP cantilevers (fo = 262–325 kHz, k = 20–80 N/m).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4590807&req=5

fig3: AFM images of FITC-labeled liposomes coupled to 90 nm gold particles and scanned on fresh cleaved mica. (a) Height image with section analysis measuring the diameter of three particles (95, 86, and 80 nm, resp.) that made up a typical gold-liposome cluster. (b) Additional digital zoom to 1 μm2 taken from the original scan at 2.5 μm (x-y). The DLS analysis showed that the gold-liposome complexes had a diameter of 285 ± 5.3 nm. Tapping mode in air using RTESP cantilevers (fo = 262–325 kHz, k = 20–80 N/m).
Mentions: To enhance AFM imaging, nanogold particles were covalently linked to FITC liposomes. We choose 90 nm gold particles to facilitate visualization within the cell membrane taking into consideration that ~120 nm gold nanoparticles are normally used for thermal ablation. Figure 3 shows AFM imaging of the geometric structure of a typical gold-liposome cluster (303 nm in size) consisting of three distinctive particles with individual diameters of 95, 86, and 80 nm.

Bottom Line: Dynasore monohydrate, an inhibitor of endocytosis, obstructed the internalization of the gold-liposomes.This study showed the versatility of the AFM technique, combined with fluorescent microscopy, for investigating liposome uptake by endothelial cells.The 90 nm colloidal gold nanoparticles proved to be a noninvasive contrast agent that efficiently improves AFM imaging during the investigation of biological nanoprocesses.

View Article: PubMed Central - PubMed

Affiliation: Division of Cardiology, Department of Internal Medicine, The University of Texas Health Science Center at Houston, 1881 East Road, Houston, TX 77054, USA.

ABSTRACT
Although atomic force microscopy (AFM) has been used extensively to characterize cell membrane structure and cellular processes such as endocytosis and exocytosis, the corrugated surface of the cell membrane hinders the visualization of extracellular entities, such as liposomes, that may interact with the cell. To overcome this barrier, we used 90 nm nanogold particles to label FITC liposomes and monitor their endocytosis on human coronary artery endothelial cells (HCAECs) in vitro. We were able to study the internalization process of gold-coupled liposomes on endothelial cells, by using AFM. We found that the gold-liposomes attached to the HCAEC cell membrane during the first 15-30 min of incubation, liposome cell internalization occurred from 30 to 60 min, and most of the gold-labeled liposomes had invaginated after 2 hr of incubation. Liposomal uptake took place most commonly at the periphery of the nuclear zone. Dynasore monohydrate, an inhibitor of endocytosis, obstructed the internalization of the gold-liposomes. This study showed the versatility of the AFM technique, combined with fluorescent microscopy, for investigating liposome uptake by endothelial cells. The 90 nm colloidal gold nanoparticles proved to be a noninvasive contrast agent that efficiently improves AFM imaging during the investigation of biological nanoprocesses.

No MeSH data available.


Related in: MedlinePlus