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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, Cukrovarnick√° 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 the tip radius on AFM topography and phase. AFM topography (a, b) of FBS layer on H-terminated MCD obtained in solution using cantilevers with different tip radius. Estimated tip radius ra ~ 30 nm, rb ~ 50 nm. Lxa = 12 nm, Lxb = 21 nm. Corresponding AFM phase images (c, d) show the difference in Lx values for phase (Lxc = 8 nm and Lxd = 22 nm). (e) The model illustrates the effect of tip shape on the broadening of features in the phase images.
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Figure 4: Influence of the tip radius on AFM topography and phase. AFM topography (a, b) of FBS layer on H-terminated MCD obtained in solution using cantilevers with different tip radius. Estimated tip radius ra ~ 30 nm, rb ~ 50 nm. Lxa = 12 nm, Lxb = 21 nm. Corresponding AFM phase images (c, d) show the difference in Lx values for phase (Lxc = 8 nm and Lxd = 22 nm). (e) The model illustrates the effect of tip shape on the broadening of features in the phase images.

Mentions: Both morphology and phase images can be influenced also by the tip shape. In Figure 4 one can see the morphology and phase images of FBS layer on H-terminated MCD obtained in TM using the medium k cantilevers (k = 3 N/m) with a nominal tip radius of r ~ 10 nm. Dark features (dots) observed in both phase images correspond to protein cores exposed on H-terminated diamond surface [8]. The observed feature size in both topography and phase is different for different cantilevers. The actual tip radius estimated using deconvolution procedure is ra ~ 30 nm for the image (a) and rb ~ 50 nm for the image (b). The sharper tip resolves smaller objects on the surface, Lxa < Lxb in the topography and Lxc < Lxd in the phase image. The number of the smaller objects is also higher. RMS values of height and phase signals are more or less the same on both surfaces.


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

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

Influence of the tip radius on AFM topography and phase. AFM topography (a, b) of FBS layer on H-terminated MCD obtained in solution using cantilevers with different tip radius. Estimated tip radius ra ~ 30 nm, rb ~ 50 nm. Lxa = 12 nm, Lxb = 21 nm. Corresponding AFM phase images (c, d) show the difference in Lx values for phase (Lxc = 8 nm and Lxd = 22 nm). (e) The model illustrates the effect of tip shape on the broadening of features in the phase images.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Influence of the tip radius on AFM topography and phase. AFM topography (a, b) of FBS layer on H-terminated MCD obtained in solution using cantilevers with different tip radius. Estimated tip radius ra ~ 30 nm, rb ~ 50 nm. Lxa = 12 nm, Lxb = 21 nm. Corresponding AFM phase images (c, d) show the difference in Lx values for phase (Lxc = 8 nm and Lxd = 22 nm). (e) The model illustrates the effect of tip shape on the broadening of features in the phase images.
Mentions: Both morphology and phase images can be influenced also by the tip shape. In Figure 4 one can see the morphology and phase images of FBS layer on H-terminated MCD obtained in TM using the medium k cantilevers (k = 3 N/m) with a nominal tip radius of r ~ 10 nm. Dark features (dots) observed in both phase images correspond to protein cores exposed on H-terminated diamond surface [8]. The observed feature size in both topography and phase is different for different cantilevers. The actual tip radius estimated using deconvolution procedure is ra ~ 30 nm for the image (a) and rb ~ 50 nm for the image (b). The sharper tip resolves smaller objects on the surface, Lxa < Lxb in the topography and Lxc < Lxd in the phase image. The number of the smaller objects is also higher. RMS values of height and phase signals are more or less the same on both surfaces.

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, Cukrovarnick√° 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