All posts by NANOSENSORS

NANOSENSORS heads the world market with its innovative high quality scanning probes for SPM (Scanning Probe Microscopy) and AFM (Atomic Force Microscopy). NANOSENSORS' AFM probes, AFM tips and Cantilevers contribute to many scientific breakthroughs in Nanotechnology.

Observing single magnetite nanoparticles with a diameter of 10nm by using NANOSENSORS SSS-MFMR AFM probes

In their publication “Understanding electrostatic and magnetic forces in magnetic force microscopy: towards single supermagnetic nanoparticle resolution” Alexander Krivcov, Tanja Junkers and Hildegard Möbius describe methods to suppress capacitive coupling effects in MFM hiding the magnetic signal of magnetic nanoparticles.

During MFM measurements performed in an interleave mode moving the tip at a certain distance to the sample surface the tip is exposed not only to magnetic forces but to electrostatic forces between tip and substrates. In case of analyzing nanoparticles laying on a flat substrate, the electrostatic forces changes noticeably with increasing tip to substrate distance whenever the tip is retracted over a nanoparticle. This capacitive signal may overwhelm the magnetic signal that should be detected instead.

The authors propose several approaches to reduce these capacitive signals. The change in electrostatic forces could be minimized by avoiding retraction of tip over the nanoparticle. Therefore, it is proposed to use interleave linear mode following a linear approximation of the sample surface instead of the interleave lift mode following the sample surface as measured. By that, changes in distance between sample substrate and tip at the nanoparticles are avoided. Moreover, they propose using a substrate with a work function comparable to that of the tip in order to reduce electrostatic forces, in general. By applying an appropriate tip bias remaining electrostatic forces could compensated and further suppressed. Finally, the authors suggest using a tip that is as sharp as possible for decreasing the area of the capacitor and NANOSENSORS SSS-MFMR probes are the best choice for this.

The impact of the above mentioned optimizations have been validated experimentally by the authors. Finally, it turned out that if using super sharp magnetic tips further methods suppressing capacitive effects were not necessary. The authors were able to detect superparamagnetic nanoparticles at the single particle level on copper substrate with a NANOSENSORS SSS-MFMR probe without using additional parameters as e. g. tip bias or external magnetic field.Figure 12 from: A. Krivcov et. al, Understanding electrostatic and magnetic forces in magnetic force microscopy: towards single supermagnetic nanoparticle resolution: Figure 12. (a) topography of copper substrate with single magnetite nanoparticle; (b) phase image in 11 nm lift height with an attraction at the place of the nanoparticle; (c) Cross section of a single magnetite nanoparticle (dotted line in (a)) with 10 nm diameter taken on copper substrate with NANOSENSORS SSS-MFMR AFM probe

Figure 12  from: A. Krivcov et. al, Understanding electrostatic and magnetic forces in magnetic force microscopy: towards single supermagnetic nanoparticle resolution: Figure 12. (a) topography of copper substrate with single magnetite nanoparticle; (b) phase image in 11 nm lift height with an attraction at the place of the nanoparticle; (c) Cross section of a single magnetite nanoparticle (dotted line in (a)) with 10 nm diameter taken on copper substrate with SSS-MFMR tip

A. Krivcov, T. Junkers, and H. Möbius
Understanding electrostatic and magnetic forces in magnetic force microscopy: towards single superparamagnetic nanoparticle resolution
J. Phys. Commun., vol. 2, no. 7, p. 075019, 2018
DOI: https://doi.org/10.1088/2399-6528/aad3a4

The article “Understanding electrostatic and magnetic forces in magnetic force microscopy: towards single superparamagnetic nanoparticle resolution” by A. Krivcov, T. Junkers, and H. Möbius is licensed under the Creative Commons Attribution 3.0 License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0.

A fibrin biofilm covers blood clots and protects from microbial invasion

New interesting publication by Macrea et. al mentioning the use of NANOSENSORS uniqprobe qp-BioAC:

“Hemostasis requires conversion of fibrinogen to fibrin fibers that generate a characteristic network, interact with blood cells, and initiate tissue repair. The fibrin network is porous and highly permeable, but the spatial arrangement of the external clot face is unknown. Here we show that fibrin transitioned to the blood-air interface through Langmuir film formation, producing a protective film confining clots in human and mouse models. We demonstrated that only fibrin is required for formation of the film, and that it occurred in vitro and in vivo. The fibrin film connected to the underlying clot network through tethering fibers. It was digested by plasmin, and formation of the film was prevented with surfactants. Functionally, the film retained blood cells and protected against penetration by bacterial pathogens in a murine model of dermal infection. Our data show a remarkable aspect of blood clotting in which fibrin forms a protective film covering the external surface of the clot, defending the organism against microbial invasion.”*

The AFM imaging and force measurements mentioned in this article were performed using CB3 of the NANOSENSORS™ uniqprobe qp-BioAC.

Supplemental Figure. 6. From Macrea et. al “A fibrin biofilm covers blood clots and protects from microbial invasion” Mechanisms and roles of fibrin film. A, Sneddon model used to calculate Young’s Modulus, where F is the force from the force curve, E is Young’s modulus, ν is Poisson’s ratio (0.5), α is the half angle for the indenter (15 degrees for our tips), and δ is the indentation. Note that this equation is only accurate with a half angle of 15 degrees for the first 200nm of indentation. B, Strength of the fibrin film in clots produced with plasma and thrombin with or without T101 (FXIII inhibitor ) investigated using atomic force microscopy (AFM). Fibrin fibres were visible under the film surface and these areas presented with stiffer Young’s modulus than fibrin film suspended between fibres. Grey lines in the zoomed-in images represent Young’s modulus scan area represented in the line force graphs. Scale bar - 2μm. C, Young’s Modulus was calculated for the suspended film and the film supported by fibers with and without T101 by fitting a Sneddon model to all AFM force curves found over the entire area that was imaged. 20 measurements were taken for each condition. **** P<0.0001. D, Clots produced from plasma with thrombin, under a layer of oil or enclosed in a ball of petroleum jelly, to eliminate the air - liquid interface, imaged by LSCM. Solid and dotted yellow lines indicate location of air liquid interface, n=3 experiments. Scale bars - 50μm. NANOSENSORS qp-BioAC AFM probes (CB3 ) were used for the AFM imaging and force measurements.
Supplemental Figure. 6. From Macrea et. al “A fibrin biofilm covers blood clots and protects from microbial invasion Mechanisms and roles of fibrin film. A, Sneddon model used to calculate Young’s Modulus, where F is the force from the force curve, E is Young’s modulus, ν is Poisson’s ratio (0.5), α is the half angle for the indenter (15 degrees for our tips), and δ is the indentation. Note that this equation is only accurate with a half angle of 15 degrees for the first 200nm of indentation. B, Strength of the fibrin film in clots produced with plasma and thrombin with or without T101 (FXIII inhibitor ) investigated using atomic force microscopy (AFM). Fibrin fibres were visible under the film surface and these areas presented with stiffer Young’s modulus than fibrin film suspended between fibres. Grey lines in the zoomed-in images represent Young’s modulus scan area represented in the line force graphs. Scale bar – 2μm. C, Young’s Modulus was calculated for the suspended film and the film supported by fibers with and without T101 by fitting a Sneddon model to all AFM force curves found over the entire area that was imaged. 20 measurements were taken for each condition. **** P<0.0001. D, Clots produced from plasma with thrombin, under a layer of oil or enclosed in a ball of petroleum jelly, to eliminate the air – liquid interface, imaged by LSCM. Solid and dotted yellow lines indicate location of air liquid interface, n=3 experiments. Scale bars – 50μm.

*Fraser L. Macrae, Cédric Duval, Praveen Papareddy, Stephen R. Baker, Nadira Yuldasheva, Katherine J. Kearney, Helen R. McPherson, Nathan Asquith, Joke Konings, Alessandro Casini, Jay L. Degen, Simon D. Connell,  Helen Philippou, Alisa S. Wolberg, Heiko Herwald, Robert A.S. Ariëns
A fibrin biofilm covers blood clots and protects from microbial invasion
Journal of  Clinical Investigation. 2018;128(8):3356-3368
DOI: https://doi.org/10.1172/JCI98734

Please follow this external link for the full article: https://www.jci.org/articles/view/98734#sd

The article “A fibrin biofilm covers blood clots and protects from microbial invasion” by Fraser L. Macrae et. al is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/ licenses/by/4.0/.

See you at AVS in Long Beach CA today

Meet our CEO this week at AVS 65th International Symposium and Exhibition in Long Beach CA.

Manfred Detterbeck at AVS 65th International Symposium and Exhibition.
Manfred Detterbeck at AVS 65th International Symposium and Exhibition. Great AVS T-Shirt!

 

Long Beach Convention Center venue of AVS 65th International Symposium and Exhibition
Another beautiful day outside Long Beach Convention Center – venue of this year’s AVS International Symposium and Exhibition.