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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

Wear of protein layers in tapping mode AFM. AFM image of FBS layer on monocrystalline diamond (MCD) in McCoy medium using NSG01 tip (NT-MDT): (a) The protein layer was removed from 2 × 2 μm2 area in CM (F ~ 600 nN). (b) The protein layer was partially removed from 4 × 4 μm2 area using 5 scans in TM (A0 ~ 60 nm, E ~ 10-15 J). (c) The protein layer was measured by TM, scan 10 × 10 μm2 (A0 ~ 60 nm). (d) FBS layer on MCD was studied in CM and TM in air using NSG01 tip. FBS layer was removed after just 2 scans with the highest amplitude (A0 ~ 700 nm, E ~ 10-12 J). (e) The scheme illustrates the TM nanoshaving experiment as shown in (a-c). (f) Wear rate dependence on free amplitude and oscillation energy for TM nanoshaving of FBS layer adsorbed on MCD using medium k (NSG01) cantilevers, rSP = 0.5.
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Figure 2: Wear of protein layers in tapping mode AFM. AFM image of FBS layer on monocrystalline diamond (MCD) in McCoy medium using NSG01 tip (NT-MDT): (a) The protein layer was removed from 2 × 2 μm2 area in CM (F ~ 600 nN). (b) The protein layer was partially removed from 4 × 4 μm2 area using 5 scans in TM (A0 ~ 60 nm, E ~ 10-15 J). (c) The protein layer was measured by TM, scan 10 × 10 μm2 (A0 ~ 60 nm). (d) FBS layer on MCD was studied in CM and TM in air using NSG01 tip. FBS layer was removed after just 2 scans with the highest amplitude (A0 ~ 700 nm, E ~ 10-12 J). (e) The scheme illustrates the TM nanoshaving experiment as shown in (a-c). (f) Wear rate dependence on free amplitude and oscillation energy for TM nanoshaving of FBS layer adsorbed on MCD using medium k (NSG01) cantilevers, rSP = 0.5.

Mentions: Figure 2 shows that FBS layer can be removed from MCD in TM in McCoy's solution even when using the medium frequency cantilevers. We applied subsequent scanning as illustrated by the scheme in Figure 2e. First, one 2 × 2 μm2 CM scan with the applied force of F ~ 600 nN completely removed the FBS layer from the MCD, as shown in Figure 2a. Afterwards, five 4 × 4 μm2 scans in TM with standard amplitude (A0 ~ 60 nm) were made. An image obtained by these scans is shown in Figure 2b. It confirms removal of the FBS layer during the previous CM scan. An overall scan 10 × 10 μm2 with the same amplitude (A0 ~ 60 nm) in Figure 2c reveals that the five previous TM measurements lead to partial removal of FBS film, too. We denote this effect as TM nanoshaving [9]. This effect is more pronounced when stiffer cantilever is used, as demonstrated already in the Figure 1c.


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

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

Wear of protein layers in tapping mode AFM. AFM image of FBS layer on monocrystalline diamond (MCD) in McCoy medium using NSG01 tip (NT-MDT): (a) The protein layer was removed from 2 × 2 μm2 area in CM (F ~ 600 nN). (b) The protein layer was partially removed from 4 × 4 μm2 area using 5 scans in TM (A0 ~ 60 nm, E ~ 10-15 J). (c) The protein layer was measured by TM, scan 10 × 10 μm2 (A0 ~ 60 nm). (d) FBS layer on MCD was studied in CM and TM in air using NSG01 tip. FBS layer was removed after just 2 scans with the highest amplitude (A0 ~ 700 nm, E ~ 10-12 J). (e) The scheme illustrates the TM nanoshaving experiment as shown in (a-c). (f) Wear rate dependence on free amplitude and oscillation energy for TM nanoshaving of FBS layer adsorbed on MCD using medium k (NSG01) cantilevers, rSP = 0.5.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Wear of protein layers in tapping mode AFM. AFM image of FBS layer on monocrystalline diamond (MCD) in McCoy medium using NSG01 tip (NT-MDT): (a) The protein layer was removed from 2 × 2 μm2 area in CM (F ~ 600 nN). (b) The protein layer was partially removed from 4 × 4 μm2 area using 5 scans in TM (A0 ~ 60 nm, E ~ 10-15 J). (c) The protein layer was measured by TM, scan 10 × 10 μm2 (A0 ~ 60 nm). (d) FBS layer on MCD was studied in CM and TM in air using NSG01 tip. FBS layer was removed after just 2 scans with the highest amplitude (A0 ~ 700 nm, E ~ 10-12 J). (e) The scheme illustrates the TM nanoshaving experiment as shown in (a-c). (f) Wear rate dependence on free amplitude and oscillation energy for TM nanoshaving of FBS layer adsorbed on MCD using medium k (NSG01) cantilevers, rSP = 0.5.
Mentions: Figure 2 shows that FBS layer can be removed from MCD in TM in McCoy's solution even when using the medium frequency cantilevers. We applied subsequent scanning as illustrated by the scheme in Figure 2e. First, one 2 × 2 μm2 CM scan with the applied force of F ~ 600 nN completely removed the FBS layer from the MCD, as shown in Figure 2a. Afterwards, five 4 × 4 μm2 scans in TM with standard amplitude (A0 ~ 60 nm) were made. An image obtained by these scans is shown in Figure 2b. It confirms removal of the FBS layer during the previous CM scan. An overall scan 10 × 10 μm2 with the same amplitude (A0 ~ 60 nm) in Figure 2c reveals that the five previous TM measurements lead to partial removal of FBS film, too. We denote this effect as TM nanoshaving [9]. This effect is more pronounced when stiffer cantilever is used, as demonstrated already in the Figure 1c.

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