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A micro-fluidic study of whole blood behaviour on PMMA topographical nanostructures.

Minelli C, Kikuta A, Tsud N, Ball MD, Yamamoto A - J Nanobiotechnology (2008)

Bottom Line: Although nano-topography has been found to influence cell behaviour, no established method exists to understand and evaluate the effects of nano-topography on polymer-blood interaction.Surface feature size varied from 40 nm to 400 nm and feature height from 5 nm to 50 nm.Whole blood flow rate through the micro-fluidic channels was found to decrease with increasing average surface feature size.

View Article: PubMed Central - HTML - PubMed

Affiliation: International Centre for Young Scientists, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan. c.minelli@imperial.ac.uk.

ABSTRACT

Background: Polymers are attractive materials for both biomedical engineering and cardiovascular applications. Although nano-topography has been found to influence cell behaviour, no established method exists to understand and evaluate the effects of nano-topography on polymer-blood interaction.

Results: We optimized a micro-fluidic set-up to study the interaction of whole blood with nano-structured polymer surfaces under flow conditions. Micro-fluidic chips were coated with polymethylmethacrylate films and structured by polymer demixing. Surface feature size varied from 40 nm to 400 nm and feature height from 5 nm to 50 nm. Whole blood flow rate through the micro-fluidic channels, platelet adhesion and von Willebrand factor and fibrinogen adsorption onto the structured polymer films were investigated. Whole blood flow rate through the micro-fluidic channels was found to decrease with increasing average surface feature size. Adhesion and spreading of platelets from whole blood and von Willebrand factor adsorption from platelet poor plasma were enhanced on the structured surfaces with larger feature, while fibrinogen adsorption followed the opposite trend.

Conclusion: We investigated whole blood behaviour and plasma protein adsorption on nano-structured polymer materials under flow conditions using a micro-fluidic set-up. We speculate that surface nano-topography of polymer films influences primarily plasma protein adsorption, which results in the control of platelet adhesion and thrombus formation.

No MeSH data available.


Related in: MedlinePlus

Characterization of the structured PMMA films. (A) AFM topographical image of PMMA3 surface, structured using the polymer demixing technique. (B) XPS C1s spectrum of a surface of pure PMMA. The spectrum is the result of the convolution of four peaks, indicated in numbers on the PMMA molecules. (C) XPS C1s spectrum of a pure PS surface. (D) XPS C1s spectrum of a surface similar to PMMA3 (black line). For comparison the spectrum relative to pure PMMA is shown (dashed line), together with the difference between the two spectra (in gray), computed overlapping the ester peaks at 289.1 eV of the two spectra, that contain the contribution of the solely PMMA.
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Figure 2: Characterization of the structured PMMA films. (A) AFM topographical image of PMMA3 surface, structured using the polymer demixing technique. (B) XPS C1s spectrum of a surface of pure PMMA. The spectrum is the result of the convolution of four peaks, indicated in numbers on the PMMA molecules. (C) XPS C1s spectrum of a pure PS surface. (D) XPS C1s spectrum of a surface similar to PMMA3 (black line). For comparison the spectrum relative to pure PMMA is shown (dashed line), together with the difference between the two spectra (in gray), computed overlapping the ester peaks at 289.1 eV of the two spectra, that contain the contribution of the solely PMMA.

Mentions: Polymer demixing is a well known technique to study the response of cells to nano-topography [20] and was used in this work to create a set of nano-structured polymer surfaces having typical feature sizes between 40 nm and 400 nm. Briefly, polymer films are spin coated from a blend of polystyrene (PS) and PMMA. Due to their immiscibility, the two polymers form separate phases during solvent evaporation. The PS phase is subsequently removed by selective solvent treatment, leaving a structured PMMA film. The geometry of the PMMA surface structures is controlled varying the experimental parameters such as polymer concentration in solution and spin velocity. This technique is fast, inexpensive and particularly suitable for the fabrication of nano-structured films onto surfaces having complex geometries [23] such as the micro-fluidic chips used in this work (Fig. 1B, C and 1D). A typical Atomic Force Microscopy (AFM) topographical image of a PMMA film surface structured by polymer demixing is shown in Figure 2A. The average feature size and height were estimated from both AFM topographical and section images of the film surfaces, and their values represent the distance between the centre of a feature and the centre of a valley between two features. The film thickness was measured from AFM section profiles after having scratched the film with Teflon tweezers. The AFM measurements were performed on different areas of the same film and on similar films; the average measured values are shown in Table 1. Film thickness varied from 10 nm to 50 nm.


A micro-fluidic study of whole blood behaviour on PMMA topographical nanostructures.

Minelli C, Kikuta A, Tsud N, Ball MD, Yamamoto A - J Nanobiotechnology (2008)

Characterization of the structured PMMA films. (A) AFM topographical image of PMMA3 surface, structured using the polymer demixing technique. (B) XPS C1s spectrum of a surface of pure PMMA. The spectrum is the result of the convolution of four peaks, indicated in numbers on the PMMA molecules. (C) XPS C1s spectrum of a pure PS surface. (D) XPS C1s spectrum of a surface similar to PMMA3 (black line). For comparison the spectrum relative to pure PMMA is shown (dashed line), together with the difference between the two spectra (in gray), computed overlapping the ester peaks at 289.1 eV of the two spectra, that contain the contribution of the solely PMMA.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2279145&req=5

Figure 2: Characterization of the structured PMMA films. (A) AFM topographical image of PMMA3 surface, structured using the polymer demixing technique. (B) XPS C1s spectrum of a surface of pure PMMA. The spectrum is the result of the convolution of four peaks, indicated in numbers on the PMMA molecules. (C) XPS C1s spectrum of a pure PS surface. (D) XPS C1s spectrum of a surface similar to PMMA3 (black line). For comparison the spectrum relative to pure PMMA is shown (dashed line), together with the difference between the two spectra (in gray), computed overlapping the ester peaks at 289.1 eV of the two spectra, that contain the contribution of the solely PMMA.
Mentions: Polymer demixing is a well known technique to study the response of cells to nano-topography [20] and was used in this work to create a set of nano-structured polymer surfaces having typical feature sizes between 40 nm and 400 nm. Briefly, polymer films are spin coated from a blend of polystyrene (PS) and PMMA. Due to their immiscibility, the two polymers form separate phases during solvent evaporation. The PS phase is subsequently removed by selective solvent treatment, leaving a structured PMMA film. The geometry of the PMMA surface structures is controlled varying the experimental parameters such as polymer concentration in solution and spin velocity. This technique is fast, inexpensive and particularly suitable for the fabrication of nano-structured films onto surfaces having complex geometries [23] such as the micro-fluidic chips used in this work (Fig. 1B, C and 1D). A typical Atomic Force Microscopy (AFM) topographical image of a PMMA film surface structured by polymer demixing is shown in Figure 2A. The average feature size and height were estimated from both AFM topographical and section images of the film surfaces, and their values represent the distance between the centre of a feature and the centre of a valley between two features. The film thickness was measured from AFM section profiles after having scratched the film with Teflon tweezers. The AFM measurements were performed on different areas of the same film and on similar films; the average measured values are shown in Table 1. Film thickness varied from 10 nm to 50 nm.

Bottom Line: Although nano-topography has been found to influence cell behaviour, no established method exists to understand and evaluate the effects of nano-topography on polymer-blood interaction.Surface feature size varied from 40 nm to 400 nm and feature height from 5 nm to 50 nm.Whole blood flow rate through the micro-fluidic channels was found to decrease with increasing average surface feature size.

View Article: PubMed Central - HTML - PubMed

Affiliation: International Centre for Young Scientists, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan. c.minelli@imperial.ac.uk.

ABSTRACT

Background: Polymers are attractive materials for both biomedical engineering and cardiovascular applications. Although nano-topography has been found to influence cell behaviour, no established method exists to understand and evaluate the effects of nano-topography on polymer-blood interaction.

Results: We optimized a micro-fluidic set-up to study the interaction of whole blood with nano-structured polymer surfaces under flow conditions. Micro-fluidic chips were coated with polymethylmethacrylate films and structured by polymer demixing. Surface feature size varied from 40 nm to 400 nm and feature height from 5 nm to 50 nm. Whole blood flow rate through the micro-fluidic channels, platelet adhesion and von Willebrand factor and fibrinogen adsorption onto the structured polymer films were investigated. Whole blood flow rate through the micro-fluidic channels was found to decrease with increasing average surface feature size. Adhesion and spreading of platelets from whole blood and von Willebrand factor adsorption from platelet poor plasma were enhanced on the structured surfaces with larger feature, while fibrinogen adsorption followed the opposite trend.

Conclusion: We investigated whole blood behaviour and plasma protein adsorption on nano-structured polymer materials under flow conditions using a micro-fluidic set-up. We speculate that surface nano-topography of polymer films influences primarily plasma protein adsorption, which results in the control of platelet adhesion and thrombus formation.

No MeSH data available.


Related in: MedlinePlus