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Investigation of size-dependent cell adhesion on nanostructured interfaces.

Kuo CW, Chueh DY, Chen P - J Nanobiotechnology (2014)

Bottom Line: It was observed that when cells were cultured on the nanopillars, the apoptosis rate slightly increased as the size of the nanopillar decreased.From this study, we conclude that cells can survive on nanostructures with a slight increase in apoptosis rate and that cells interact very strongly with smaller nanostructures.Our results indicate that in addition to substrate rigidity, nanostructure dimensions are additional important physical parameters that can be used to regulate behaviour of cells.

View Article: PubMed Central - PubMed

Affiliation: Research Center for Applied Sciences, Academia Sinica, 128, Section 2, Academia Road, Nankang, Taipei, 11529, Taiwan. kuo55@gate.sinica.edu.tw.

ABSTRACT

Background: Cells explore the surfaces of materials through membrane-bound receptors, such as the integrins, and use them to interact with extracellular matrix molecules adsorbed on the substrate surfaces, resulting in the formation of focal adhesions. With recent advances in nanotechnology, biosensors and bioelectronics are being fabricated with ever decreasing feature sizes. The performances of these devices depend on how cells interact with nanostructures on the device surfaces. However, the behavior of cells on nanostructures is not yet fully understood. Here we present a systematic study of cell-nanostructure interaction using polymeric nanopillars with various diameters.

Results: We first checked the viability of cells grown on nanopillars with diameters ranging from 200 nm to 700 nm. It was observed that when cells were cultured on the nanopillars, the apoptosis rate slightly increased as the size of the nanopillar decreased. We then calculated the average size of the focal adhesions and the cell-spreading area for focal adhesions using confocal microscopy. The size of focal adhesions formed on the nanopillars was found to decrease as the size of the nanopillars decreased, resembling the formations of nascent focal complexes. However, when the size of nanopillars decreased to 200 nm, the size of the focal adhesions increased. Further study revealed that cells interacted very strongly with the nanopillars with a diameter of 200 nm and exerted sufficient forces to bend the nanopillars together, resulting in the formation of larger focal adhesions.

Conclusions: We have developed a simple approach to systematically study cell-substrate interactions on physically well-defined substrates using size-tunable polymeric nanopillars. From this study, we conclude that cells can survive on nanostructures with a slight increase in apoptosis rate and that cells interact very strongly with smaller nanostructures. In contrast to previous observations on flat substrates that cells interacted weakly with softer substrates, we observed strong cell-substrate interactions on the softer nanopillars with smaller diameters. Our results indicate that in addition to substrate rigidity, nanostructure dimensions are additional important physical parameters that can be used to regulate behaviour of cells.

No MeSH data available.


Related in: MedlinePlus

Scanning electron micrographs of polymeric nanopillar arrays made of UV-curable adhesive. The diameters of the nanopillars are (a) 214 ± 13 nm, (b) 322 ± 16 nm, (c) 425 ± 17 nm, (d) 500 ± 19 nm, and (e) 684 ± 17 nm. Scale bars are 1 μm.
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Fig2: Scanning electron micrographs of polymeric nanopillar arrays made of UV-curable adhesive. The diameters of the nanopillars are (a) 214 ± 13 nm, (b) 322 ± 16 nm, (c) 425 ± 17 nm, (d) 500 ± 19 nm, and (e) 684 ± 17 nm. Scale bars are 1 μm.

Mentions: In recent years, nanosphere lithography has been utilized to fabricate well-ordered periodic nanostructures over large areas [33,34]. In this experiment, nanosphere lithography was employed to fabricate nanohole arrays to be used as replication masters, which were then used to produce nanopillars with various dimensions, as shown in Figure 1. Several curable polymers, such as PDMS, h-PDMS, PMMA, Teflon and SU-8 photo-resist, have been used to replicate the nanostructure of the silicon nanohole arrays. In this experiment, we selected a UV-curable adhesive (NOA 61, Norland) to produce the nanopillars due to the simplicity of its use in fabrication. Figure 2 presents SEM images of size-tunable polymeric nanopillar arrays made of UV-curable adhesive. The diameters of the nanopillars ranged from 200 nm to 700 nm, and their heights ranged from 700 nm to 1000 nm. The measured diameters and heights of the fabricated nanopillars are listed in Table 1, as well as the calculated rigidity, which decreased from 94 nN/nm for the nanopillars 680 nm in diameter and 660 nm in height to 0.26 nN/nm for the nanopillars 200 nm in diameter and 800 nm in height. The biocompatibility of the polymeric nanopillars could be improved by coating their surfaces with a layer of ECM molecules, such as fibronectin.Figure 1


Investigation of size-dependent cell adhesion on nanostructured interfaces.

Kuo CW, Chueh DY, Chen P - J Nanobiotechnology (2014)

Scanning electron micrographs of polymeric nanopillar arrays made of UV-curable adhesive. The diameters of the nanopillars are (a) 214 ± 13 nm, (b) 322 ± 16 nm, (c) 425 ± 17 nm, (d) 500 ± 19 nm, and (e) 684 ± 17 nm. Scale bars are 1 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4265325&req=5

Fig2: Scanning electron micrographs of polymeric nanopillar arrays made of UV-curable adhesive. The diameters of the nanopillars are (a) 214 ± 13 nm, (b) 322 ± 16 nm, (c) 425 ± 17 nm, (d) 500 ± 19 nm, and (e) 684 ± 17 nm. Scale bars are 1 μm.
Mentions: In recent years, nanosphere lithography has been utilized to fabricate well-ordered periodic nanostructures over large areas [33,34]. In this experiment, nanosphere lithography was employed to fabricate nanohole arrays to be used as replication masters, which were then used to produce nanopillars with various dimensions, as shown in Figure 1. Several curable polymers, such as PDMS, h-PDMS, PMMA, Teflon and SU-8 photo-resist, have been used to replicate the nanostructure of the silicon nanohole arrays. In this experiment, we selected a UV-curable adhesive (NOA 61, Norland) to produce the nanopillars due to the simplicity of its use in fabrication. Figure 2 presents SEM images of size-tunable polymeric nanopillar arrays made of UV-curable adhesive. The diameters of the nanopillars ranged from 200 nm to 700 nm, and their heights ranged from 700 nm to 1000 nm. The measured diameters and heights of the fabricated nanopillars are listed in Table 1, as well as the calculated rigidity, which decreased from 94 nN/nm for the nanopillars 680 nm in diameter and 660 nm in height to 0.26 nN/nm for the nanopillars 200 nm in diameter and 800 nm in height. The biocompatibility of the polymeric nanopillars could be improved by coating their surfaces with a layer of ECM molecules, such as fibronectin.Figure 1

Bottom Line: It was observed that when cells were cultured on the nanopillars, the apoptosis rate slightly increased as the size of the nanopillar decreased.From this study, we conclude that cells can survive on nanostructures with a slight increase in apoptosis rate and that cells interact very strongly with smaller nanostructures.Our results indicate that in addition to substrate rigidity, nanostructure dimensions are additional important physical parameters that can be used to regulate behaviour of cells.

View Article: PubMed Central - PubMed

Affiliation: Research Center for Applied Sciences, Academia Sinica, 128, Section 2, Academia Road, Nankang, Taipei, 11529, Taiwan. kuo55@gate.sinica.edu.tw.

ABSTRACT

Background: Cells explore the surfaces of materials through membrane-bound receptors, such as the integrins, and use them to interact with extracellular matrix molecules adsorbed on the substrate surfaces, resulting in the formation of focal adhesions. With recent advances in nanotechnology, biosensors and bioelectronics are being fabricated with ever decreasing feature sizes. The performances of these devices depend on how cells interact with nanostructures on the device surfaces. However, the behavior of cells on nanostructures is not yet fully understood. Here we present a systematic study of cell-nanostructure interaction using polymeric nanopillars with various diameters.

Results: We first checked the viability of cells grown on nanopillars with diameters ranging from 200 nm to 700 nm. It was observed that when cells were cultured on the nanopillars, the apoptosis rate slightly increased as the size of the nanopillar decreased. We then calculated the average size of the focal adhesions and the cell-spreading area for focal adhesions using confocal microscopy. The size of focal adhesions formed on the nanopillars was found to decrease as the size of the nanopillars decreased, resembling the formations of nascent focal complexes. However, when the size of nanopillars decreased to 200 nm, the size of the focal adhesions increased. Further study revealed that cells interacted very strongly with the nanopillars with a diameter of 200 nm and exerted sufficient forces to bend the nanopillars together, resulting in the formation of larger focal adhesions.

Conclusions: We have developed a simple approach to systematically study cell-substrate interactions on physically well-defined substrates using size-tunable polymeric nanopillars. From this study, we conclude that cells can survive on nanostructures with a slight increase in apoptosis rate and that cells interact very strongly with smaller nanostructures. In contrast to previous observations on flat substrates that cells interacted weakly with softer substrates, we observed strong cell-substrate interactions on the softer nanopillars with smaller diameters. Our results indicate that in addition to substrate rigidity, nanostructure dimensions are additional important physical parameters that can be used to regulate behaviour of cells.

No MeSH data available.


Related in: MedlinePlus