Limits...
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

Tip shape measured after approach to the surface. (a) Approach curve in TM at Ntegra AFM (NT-MDT) in solution shows that during the first contact amplitude of oscillation A became zero. After few seconds the piezotube oscillations cause generations of the amplitude. (b) The Multi75Al tip shape, measured using TGT1 grating. (c) The model illustrates that the measured tip shape is convolution of a real tip shape and grating profile.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211425&req=5

Figure 6: Tip shape measured after approach to the surface. (a) Approach curve in TM at Ntegra AFM (NT-MDT) in solution shows that during the first contact amplitude of oscillation A became zero. After few seconds the piezotube oscillations cause generations of the amplitude. (b) The Multi75Al tip shape, measured using TGT1 grating. (c) The model illustrates that the measured tip shape is convolution of a real tip shape and grating profile.

Mentions: The tip condition can be changed already during the initial approach to the surface. Such effect is demonstrated by Figure 6. Figure 6a shows that during cantilever approach in TM the amplitude of its oscillations approached zero. This effect is not affected by cantilever or sample. In addition, there are amplitude oscillations after the approach. Possible reasons of the oscillations are closed-loop system of the scanner and high mass of fluid cell loaded on the scanner. Thus even standard scanner feedback gain can cause oscillations. During these oscillations the amplitude also approaches zero. Several out-of-the-box tips with nominal tip radius of 10 nm were approached to the surface of the TGT1 grating and their shapes were measured by AFM, as shown in Figure 6b. The measured radius r was ranging from 50 to 200 nm. The sharpest cantilevers had r ~ 25 nm. This number actually corresponds well to the nominal tip radius, because the measured tip radius is inherently convolution of the tip and grating profiles, as illustrated by Figure 6c.


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

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

Tip shape measured after approach to the surface. (a) Approach curve in TM at Ntegra AFM (NT-MDT) in solution shows that during the first contact amplitude of oscillation A became zero. After few seconds the piezotube oscillations cause generations of the amplitude. (b) The Multi75Al tip shape, measured using TGT1 grating. (c) The model illustrates that the measured tip shape is convolution of a real tip shape and grating profile.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: Tip shape measured after approach to the surface. (a) Approach curve in TM at Ntegra AFM (NT-MDT) in solution shows that during the first contact amplitude of oscillation A became zero. After few seconds the piezotube oscillations cause generations of the amplitude. (b) The Multi75Al tip shape, measured using TGT1 grating. (c) The model illustrates that the measured tip shape is convolution of a real tip shape and grating profile.
Mentions: The tip condition can be changed already during the initial approach to the surface. Such effect is demonstrated by Figure 6. Figure 6a shows that during cantilever approach in TM the amplitude of its oscillations approached zero. This effect is not affected by cantilever or sample. In addition, there are amplitude oscillations after the approach. Possible reasons of the oscillations are closed-loop system of the scanner and high mass of fluid cell loaded on the scanner. Thus even standard scanner feedback gain can cause oscillations. During these oscillations the amplitude also approaches zero. Several out-of-the-box tips with nominal tip radius of 10 nm were approached to the surface of the TGT1 grating and their shapes were measured by AFM, as shown in Figure 6b. The measured radius r was ranging from 50 to 200 nm. The sharpest cantilevers had r ~ 25 nm. This number actually corresponds well to the nominal tip radius, because the measured tip radius is inherently convolution of the tip and grating profiles, as illustrated by Figure 6c.

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