AFM Applications in Nanoparticle Analysis
Updated: Jul 22
Dimensional measurements of nanoparticles are critical for their applicability in a variety of disciplines. Because the unique features of nanoparticles are heavily dependent on their size, it is critical to be able to describe and manipulate nanoparticle sizes. A very minor change in the diameter of a quantum dot nanoparticle, for example, will result in radically altered photoluminescence properties. The size of metallic nanoparticles affects light absorption and scattering characteristics, which are critical for various applications, including illness detection and therapy. Many additional features, like as magnetic and mechanical capabilities, interactions with cells and tissues, and so on, are affected by nanoparticle size. The form of nanoparticles has a significant impact on these characteristics as well.
Thus, in nanoscience, it is critical to have a tool that can simply characterize the size and form of nanoparticles with sub-nanometer precision, regardless of the substance of which they are comprised. The image below depicts AFM imaging of several nanoparticle kinds.
AFM images of silica nanospheres, organometallic nanorods, and gold nanotriangles are shown above (L-R). Figure 7.11 from Eaton and West's Atomic Force Microscopy.
AFM meets these criteria; z-axis (height) measurements in AFM can be precise to 0.1 nm. AFM provides numerous additional advantages for characterizing nanoparticles:
Other than basic topography, AFM can characterize magnetic and mechanical characteristics.
AFM can scan organic and inorganic components, such as the interaction of nanoparticles and biomolecules
Unlike light scattering methods, AFM (like other microscopic techniques) may be used to characterize nanoparticle mixes (see example below). For approaches like DLS, mixed samples will only yield average findings; frequently, only the bigger component will be recognized.
The picture above displays an AFM image of a mixed population of nanoparticles, with (inset) histograms of the nanoparticle sizes measured from the images.
Another benefit over light scattering methods is the ability to characterize both form and size.
AFM provides good contrast on any material, but electron microscopy frequently provides weak contrast on organic materials.
Finally, atomic force microscopy, or AFM, is an excellent technique for characterizing the size and form of a wide range of nanoparticles.
This article was based in part on Eaton and West's Atomic Force Microscopy.
1. Baptista et al., Nanoparticles in Molecular Diagnostics, Progr. Mol. Biol. Trans. Sci. 104, 427-488 (2011)
2. Eaton and West, Oxford University Press, 2010. ISBN: 978-0199570454
3. Eaton et al, Imaging Gold Nanoparticles for DNA Sequence Recognition in Biomedical Applications, IEEE Trans. NanoBioScience 6(4), 282 - 288 (2007)