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bOptimizing atomic force microscopy for characterization of diamond-protein interfaces.

Rezek B, Ukraintsev E, Kromka A - Nanoscale Res Lett (2011)

Bottom Line: We show that both diamond and proteins can be mechanically modified by Si AFM cantilever.We propose how to choose suitable cantilever type, optimize scanning parameters, recognize and minimize various artifacts, and obtain reliable AFM data both in solution and in air to reveal microscopic characteristics of protein-diamond interfaces.We also suggest that monocrystalline diamond is well defined substrate that can be applicable for fundamental studies of molecules on surfaces in general.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 16253 Prague 6, Czech Republic. ukraints@fzu.cz.

ABSTRACT
Atomic force microscopy (AFM) in contact mode and tapping mode is employed for high resolution studies of soft organic molecules (fetal bovine serum proteins) on hard inorganic diamond substrates in solution and air. Various effects in morphology and phase measurements related to the cantilever spring constant, amplitude of tip oscillations, surface approach, tip shape and condition are demonstrated and discussed based on the proposed schematic models. We show that both diamond and proteins can be mechanically modified by Si AFM cantilever. We propose how to choose suitable cantilever type, optimize scanning parameters, recognize and minimize various artifacts, and obtain reliable AFM data both in solution and in air to reveal microscopic characteristics of protein-diamond interfaces. We also suggest that monocrystalline diamond is well defined substrate that can be applicable for fundamental studies of molecules on surfaces in general.

No MeSH data available.


Related in: MedlinePlus

Influence of tip changes on AFM topography and phase. AFM image of FBS layer on MCD surface in air observed by Multi75Al (Budget Sensors) cantilever: (a) topography, (b) phase image. (c) The raw phase data showing that contrast between FBS and diamond changed sign during the measurement. (d) The model represents AFM cantilever and protein layer with square opening on diamond surface after the tip has captured a protein from FBS layer. The slow scan direction was from bottom to top of the images.
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Figure 5: Influence of tip changes on AFM topography and phase. AFM image of FBS layer on MCD surface in air observed by Multi75Al (Budget Sensors) cantilever: (a) topography, (b) phase image. (c) The raw phase data showing that contrast between FBS and diamond changed sign during the measurement. (d) The model represents AFM cantilever and protein layer with square opening on diamond surface after the tip has captured a protein from FBS layer. The slow scan direction was from bottom to top of the images.

Mentions: The tip condition can change during scanning. Figure 5 shows the topography and phase of the FBS layer on MCD, where the central region of 4 × 4 μm2 was nanoshaved using CM and TM. The phase image in Figure 5b and the phase profiles in Figure 5c show that the phase contrast between FBS and diamond changes abruptly both the sign and amplitude during scanning. The topography image looks as if something is dragged on the surface before the phase contrast changed. The image is more "noisy" in that part, but otherwise there are no quantitative changes. After the change of phase the topography image becomes less noisy for some time. Before the scan is finished, it abruptly becomes noisy again. Same effect can be observed in the phase image and profile. Hence the tip has obviously reversibly changed, most likely by releasing and re-capturing some proteins. This process is schematically shown in Figure 5d.


bOptimizing atomic force microscopy for characterization of diamond-protein interfaces.

Rezek B, Ukraintsev E, Kromka A - Nanoscale Res Lett (2011)

Influence of tip changes on AFM topography and phase. AFM image of FBS layer on MCD surface in air observed by Multi75Al (Budget Sensors) cantilever: (a) topography, (b) phase image. (c) The raw phase data showing that contrast between FBS and diamond changed sign during the measurement. (d) The model represents AFM cantilever and protein layer with square opening on diamond surface after the tip has captured a protein from FBS layer. The slow scan direction was from bottom to top of the images.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211425&req=5

Figure 5: Influence of tip changes on AFM topography and phase. AFM image of FBS layer on MCD surface in air observed by Multi75Al (Budget Sensors) cantilever: (a) topography, (b) phase image. (c) The raw phase data showing that contrast between FBS and diamond changed sign during the measurement. (d) The model represents AFM cantilever and protein layer with square opening on diamond surface after the tip has captured a protein from FBS layer. The slow scan direction was from bottom to top of the images.
Mentions: The tip condition can change during scanning. Figure 5 shows the topography and phase of the FBS layer on MCD, where the central region of 4 × 4 μm2 was nanoshaved using CM and TM. The phase image in Figure 5b and the phase profiles in Figure 5c show that the phase contrast between FBS and diamond changes abruptly both the sign and amplitude during scanning. The topography image looks as if something is dragged on the surface before the phase contrast changed. The image is more "noisy" in that part, but otherwise there are no quantitative changes. After the change of phase the topography image becomes less noisy for some time. Before the scan is finished, it abruptly becomes noisy again. Same effect can be observed in the phase image and profile. Hence the tip has obviously reversibly changed, most likely by releasing and re-capturing some proteins. This process is schematically shown in Figure 5d.

Bottom Line: We show that both diamond and proteins can be mechanically modified by Si AFM cantilever.We propose how to choose suitable cantilever type, optimize scanning parameters, recognize and minimize various artifacts, and obtain reliable AFM data both in solution and in air to reveal microscopic characteristics of protein-diamond interfaces.We also suggest that monocrystalline diamond is well defined substrate that can be applicable for fundamental studies of molecules on surfaces in general.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 16253 Prague 6, Czech Republic. ukraints@fzu.cz.

ABSTRACT
Atomic force microscopy (AFM) in contact mode and tapping mode is employed for high resolution studies of soft organic molecules (fetal bovine serum proteins) on hard inorganic diamond substrates in solution and air. Various effects in morphology and phase measurements related to the cantilever spring constant, amplitude of tip oscillations, surface approach, tip shape and condition are demonstrated and discussed based on the proposed schematic models. We show that both diamond and proteins can be mechanically modified by Si AFM cantilever. We propose how to choose suitable cantilever type, optimize scanning parameters, recognize and minimize various artifacts, and obtain reliable AFM data both in solution and in air to reveal microscopic characteristics of protein-diamond interfaces. We also suggest that monocrystalline diamond is well defined substrate that can be applicable for fundamental studies of molecules on surfaces in general.

No MeSH data available.


Related in: MedlinePlus