Removing Material Using Atomic Force Microscopy with Single‐ and Multiple‐Tip Sources

Tseng, Ampere A.

doi:10.1002/smll.201100486

Cited by 65 publications

(45 citation statements)

References 109 publications

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“…All of the images obtained had dimensions of 1 by 1 m 2 . When the protein layer was very dense, we used a nanolithography technique to determine the actual thickness of the adsorbed layer (42,43). For that, we increased the image size to 3 by 3 m 2 , switched the microscope to the contact mode, and scratched a protein layer patch with dimensions of 0.7 by 0.7 m 2 off using a cantilever with a nominal spring constant of 0.12 N/m and a tip radius of approximately 10 nm (Bruker).…”

Section: Purification Of M1 Proteinmentioning

confidence: 99%

“…To test this prediction, 3:7 DOPS-DOPC LUVs were loaded with the highly fluorescent Tb 3ϩ -DPA complex with EDTA in the outer buffer. EDTA chelates Tb 3ϩ so that leakage of liposomes would result in a decrease in total fluorescence (42). As we are interested in the disintegrating effect of M1 only, we needed to subtract from the observed total leakage any possible component of leakage due to vesicle fusion, which is expected to take place at an acidic pH.…”

Section: M1 Adsorption At Neutral Phmentioning

confidence: 99%

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pH-Dependent Formation and Disintegration of the Influenza A Virus Protein Scaffold To Provide Tension for Membrane Fusion

Batishchev

Shilova

Kachala

et al. 2016

J Virol

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Influenza virus is taken up from a pH-neutral extracellular milieu into an endosome, whose contents then acidify, causing changes in the viral matrix protein (M1) that coats the inner monolayer of the viral lipid envelope. At a pH of ϳ6, M1 interacts with the viral ribonucleoprotein (RNP) in a putative priming stage; at this stage, the interactions of the M1 scaffold coating the lipid envelope are intact. The M1 coat disintegrates as acidification continues to a pH of ϳ5 to clear a physical path for the viral genome to transit from the viral interior to the cytoplasm. Here we investigated the physicochemical mechanism of M1's pHdependent disintegration. In neutral media, the adsorption of M1 protein on the lipid bilayer was electrostatic in nature and reversible. The energy of the interaction of M1 molecules with each other in M1 dimers was about 10 times as weak as that of the interaction of M1 molecules with the lipid bilayer. Acidification drives conformational changes in M1 molecules due to changes in the M1 charge, leading to alterations in their electrostatic interactions. Dropping the pH from 7.1 to 6.0 did not disturb the M1 layer; dropping it lower partially desorbed M1 because of increased repulsion between M1 monomers still stuck to the membrane. Lipid vesicles coated with M1 demonstrated pH-dependent rupture of the vesicle membrane, presumably because of the tension generated by this repulsive force. Thus, the disruption of the vesicles coincident with M1 protein scaffold disintegration at pH 5 likely stretches the lipid membrane to the point of rupture, promoting fusion pore widening for RNP release. IMPORTANCEInfluenza remains a top killer of human beings throughout the world, in part because of the influenza virus's rapid binding to cells and its uptake into compartments hidden from the immune system. To attack the influenza virus during this time of hiding, we need to understand the physical forces that allow the internalized virus to infect the cell. In particular, we need to know how the protective coat of protein inside the viral surface reacts to the changes in acid that come soon after internalization. We found that acid makes the molecules of the protein coat push each other while they are still stuck to the virus, so that they would like to rip the membrane apart. This ripping force is known to promote membrane fusion, the process by which infection actually occurs. While it is becoming clearer that multiple processes unite to form a pathway for the entry of the influenza virus after its uptake into endosomes, it is not yet clear how and to what extent the pH-driven changes in the viral matrix contribute to that pathway. Influenza virus is an enveloped negative-strand RNA virus of the Orthomyxoviridae family (1). Its outer envelope consists of a host cell-derived bilayer lipid membrane (BLM) with the incorporated glycoproteins hemagglutinin (HA) and neuraminidase along with proton channel M2. The inner envelope of the virion is a membrane-associated scaffold of matrix protein M1, w...

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Section: Purification Of M1 Proteinmentioning

confidence: 99%

Section: M1 Adsorption At Neutral Phmentioning

confidence: 99%

pH-Dependent Formation and Disintegration of the Influenza A Virus Protein Scaffold To Provide Tension for Membrane Fusion

Batishchev

Shilova

Kachala

et al. 2016

J Virol

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“…Just like the electrochemical reaction during local anode oxidation, tribochemical reaction provides additional energy loading pathway for the material removal17. However, the contact pressures P c during anodic oxidation by Pt-coated AFM tip was estimated to be 1 ~ 2 GPa when the tip radius was about 50 nm38, which was still higher than the contact pressure during the tribochemistry-assisted nanofabrication in this study.…”

Section: Resultsmentioning

confidence: 58%

“…It is well-known that grooves could be formed on a surface when the yield of material occurred1718. When a diamond tip was used, the lowest limit of the contact pressure for the fabrication of grooves on GaAs surface was about 4.9 GPa, under which the contact area of GaAs yielded (Supplementary Section 1).…”

Section: Resultsmentioning

confidence: 99%

Nondestructive tribochemistry-assisted nanofabrication on GaAs surface

Song

Dong

et al. 2015

Sci Rep

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A tribochemistry-assisted method has been developed for nondestructive surface nanofabrication on GaAs. Without any applied electric field and post etching, hollow nanostructures can be directly fabricated on GaAs surfaces by sliding a SiO2 microsphere under an ultralow contact pressure in humid air. TEM observation on the cross-section of the fabricated area shows that there is no appreciable plastic deformation under a 4 nm groove, confirming that GaAs can be removed without destruction. Further analysis suggests that the fabrication relies on the tribochemistry with the participation of vapor in humid air. It is proposed that the formation and breakage of GaAs-O-Si bonding bridges are responsible for the removal of GaAs material during the sliding process. As a nondestructive and conductivity-independent method, it will open up new opportunities to fabricate defect-free and well-ordered nucleation positions for quantum dots on GaAs surfaces.

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“…With the rise in interest in both novel and biological materials, AFM nanomachining on graphene [20] and cell walls [21] have also been studied. However, direct AFM nanomachining is limited in fabrication speed and performance [22]. At the same time, the large normal force leads to considerable tip wear.…”

mentioning

confidence: 99%

Subnanomachining by Ultrasonic-Vibration-Assisted Atomic Force Microscopy

Shi

Liu

Zhou

et al. 2015

IEEE Trans. Nanotechnology

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Abstract-The ultrasonic vibration (UV)-assisted method, as an innovative nanomachining process, has competitive advantages compared to traditional atomic force microscopy (AFM) nanomachining methods. However, the mechanism of nanomachining by ultrasonic-assisted AFM is still unclear. Furthermore, the mathematical control model for the nanomachining process is still lacking. Therefore, the UV-assisted nanomachining process is difficult to control on the nanometer-thick film, and no additional work has been reported at this time. In this paper, the mechanisms of ultrasonic-assisted AFM subnanomachining have been analyzed by using a point-mass model for the dynamic AFM cantilever, and a mathematical model of ultrasonic subnanomachining has been established on the basis of these mechanisms. The subnanomachining experiments were carried out on a 5-nm-thick polystyrene thin film using AFM under sample UV conditions. The experimental results have shown that the amplitude of sample UV can regulate the subnanomachining depth. Finally, the simulation results from the mathematical model and the experimental results have been compared in this study.Index Terms-Atomic force microscopy (AFM), dynamic cantilever model, subnanomachining, ultrasonic-assisted machining.

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Removing Material Using Atomic Force Microscopy with Single‐ and Multiple‐Tip Sources

Cited by 65 publications

References 109 publications

pH-Dependent Formation and Disintegration of the Influenza A Virus Protein Scaffold To Provide Tension for Membrane Fusion

pH-Dependent Formation and Disintegration of the Influenza A Virus Protein Scaffold To Provide Tension for Membrane Fusion

Nondestructive tribochemistry-assisted nanofabrication on GaAs surface

Subnanomachining by Ultrasonic-Vibration-Assisted Atomic Force Microscopy

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