Abstract
Atomic force microscopy (AFM) can characterize nanomaterial elasticity. However, some one-dimensional nanomaterials, such as DNA, are too small to locate with an AFM tip because of thermal drift and the nonlinearity of piezoelectric actuators. In this study, we propose a novel approach to address the shortcomings of AFM and obtain the radial Young’s modulus of a DNA duplex. The elastic properties are evaluated by combining physical calculations and measured experimental results. The initial elasticity of the DNA is first assumed; based on tapping-mode scanning images and tip–sample interaction force simulations, the calculated elastic modulus is extracted. By minimizing the error between the assumed and experimental values, the extracted elasticity is assigned as the actual modulus for the material. Furthermore, tapping-mode image scanning avoids the necessity of locating the probe exactly on the target sample. In addition to elasticity measurements, the deformation caused by the tapping force from the AFM tip is compensated and the original height of the DNA is calculated. The results show that the radial compressive Young’s modulus of DNA is 125–150 MPa under a tapping force of 0.5–1.3 nN; its original height is 1.9 nm. This approach can be applied to the measurement of other nanomaterials.
Highlights
After the DNA origami technique was developed [1], DNA and assembled structures [2,3,4,5] have been suggested as connections for other nanostructures to construct high-order devices and systems [6,7] because they offer high yield and strong attachment to metals [8], semiconductors [9], and biomaterials [10,11]
The stiffness of the DNA duplex obtained with our method was higher than that measured by other researardcihaIlenerltsahsi[ts3ic1sitt]yu,dawnyd,haoincrihgAiinFsaMlahbteaoipguphittno5gf–-Dm3N0odAMedsPucpaanleinxnienstght-hberaofsuoegdrhcmea ecrtoahmnodbgienwaoatisfonp≈roo6fp0tho–es1eo6dre0ttiopcamNl ce.aalTscuuhrlieastitodhneiscrepancy is likely fraonmd extwpeorimpernimtalamreyasrueraesmoennsts
Multi-harmonic atomic force microscopy is a good choice for obtaining the mechanical properties at the pico-newton scale [32,33,34]
Summary
After the DNA origami technique was developed [1], DNA and assembled structures [2,3,4,5] have been suggested as connections for other nanostructures to construct high-order devices and systems [6,7] because they offer high yield and strong attachment to metals [8], semiconductors [9], and biomaterials [10,11] To stabilize such systems and devices, understanding the elastic properties of DNA duplexes is necessary. Some physical phenomena, such as thermal distortion and plastic deformation, consume some energy, inducing errors This method is not applicable for nanowires of unknown original heights. The original height of a DNA duplex was calculated by compensating for the indentation caused by the tapping force from the AFM probe tip
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