We love hearing and reading about research involving AFM & SPM at NuNano – whether that research is using our probes or not. AFM continues to break into new territories and deliver data and images back from these new frontiers with a regularity that is as fascinating as it is breathtaking.
Throughout the year we keep an eye out for publications. Some come to us directly, some via Social Media, and some through our own Google Scholar searching, often based on, ‘I wonder if anyone has ever used AFM to…’ Almost always, wherever that sentence ends, the answer is yes!
Here are our picks from 2023, a combination of community contributions and papers chosen by us. We hope you enjoy this nano window into some of the places and spaces where AFM & SPM have found themselves this year…
1) Opening this year with Daniel Wegner’s paper published in Science (Radboud University, The Netherlands) - Quantum simulator to emulate lower-dimensional molecular structure – Daniel captured our attention earlier this year at the MMC conference through his talk on the same topic. This paper used scanning tunnelling microscopy (STM) and spectroscopy to show that artificial atoms created using cesium rings, could be manipulated to mimic molecules as well as atoms. There’s a lot of thinking about chemical bonding in this one, so it’s easy to see why it ignited the interest of former chemistry undergraduate, our resident AFM Applications Engineer Jamie Goodchild.
2) Sticking with Quantum the Quantum Twisting Microscope (QTM) published in Nature earlier this year also caught our attention. By merging two scanning probe microscopy techniques (AFM & STM) together into one, they formed a tool capable of twisting ultrathin atomic layers relative to each other and measuring their electronic properties at the same time. This has offered a new angle (no pun intended) for studying the electronic properties of the very in fashion 2D materials (Van Der Waal Heterostructures). This is made possible by using a pyramidal AFM tip with a plateau on top formed by focussed ion beam (FIB) milling. A graphene layer is formed on the AFM tip which enables the probe to both act as another layer in the 2D material while simultaneously measuring electronic properties. The very cool use of an AFM probe might explain why we liked this paper so much.
3) Our first entry for a paper nominated by one of our AFM community members is on Atomically Resolved Defects on Thin Molybdenum Carbide (α-Mo2C) Crystals. The explanation they gave for their selection of this paper is given in full below:
“In this paper, the authors utilized conductive atomic force microscopy for atomic-resolution imaging to study defects at the atomic scale on a transition metal carbide. First, I am impressed with the resolution the authors were able to achieve under ambient conditions, as it enables atomic-scale investigations of surfaces without the requirement of costly vacuum setups. Additionally, the exploration of atomic-scale defects, a crucial aspect of materials science, holds significant promise for offering insights into synthesis recipes. Specifically, it may offer constructive feedback for controlling the formation and density of defects in these materials. This contribution opens a more accessible avenue for researchers to explore the intricate realm of atomic-scale surface studies, potentially influencing synthesis strategies for enhanced material properties.”
Having taken a look at the paper ourselves (thanks so much for bringing it to our attention) we quite agree it’s a corker of a paper and a brilliant addition to our end-of-year round-up.
4) At the University of Leeds they’ve been exploring Intramolecular Force Mapping at Room Temperature. Adam Sweetman and team have been measuring the force between atoms using non-contact AFM. Normally this is only possible at cryogenic temperatures but by using semiconductor materials to keep the molecules stable and to make the tip of the probe more robust, and by using atom tracking drift correction software, they’ve been able to achieve this at room temperature – aka more like real life.
Adaptive Height Δf overview AFM image of organic molecules (NTCDI) adsorbed on the Si(111)-(7 × 7) surface at room temperature. B-E show the aromatic ring structure of NTCDI. Taken from https://pubs.acs.org/doi/10.1021/acsnano.2c09463
5) The next paper is from the Scheuring Lab on the subject of A pentameric TRPV3 channel with a dilated pore. This paper documents their novel discovery in the study of transient receptor potential (TRP) channels, crucial protein ion channels for various physiological functions and drug development targets. Using high-speed atomic force microscopy (HS-AFM) and cryogenic-electron microscopy (cryo-EM) they found that TRPV3, a type of TRP channel, can exist not only in the known tetrameric form (four units) but also in a pentameric form (five units). This discovery introduces a new mechanism for structural changes in TRP channels and opens up new possibilities for research into these crucial channels.
6) In Enhanced surface nanoanalytics of transient biomolecular processes we see another new technique developed to improve longstanding issues with biomolecular sample preparation. By introducing and developing a ‘lab-on-a-chip’ spray approach to sample prep and then using multiple techniques to characterise the samples afterwards – AFM, elctron microscopy and spectroscopy – the team at Cambridge have been able to not only speed up the process of biomolecular characterisation, but to do the work at temperatures and in a way that more accurately replicates the natural conditions inside the body. The team then tested their new method on a protein linked to Parkinson’s disease (α-synuclein). They could observe the early stages of this protein's self-assembly into larger amyloid structures, which are crucial for understanding the disease's development.
Conformational properties of the early assemblies in an amyloid formation process. Taken from https://www.science.org/doi/full/10.1126/sciadv.abq3151
7) Methodologies and models for measuring viscoelastic properties of cancer cells: Towards a universal classification used four mechanical models to analyse cancer cells' elasticity and energy dissipation, finding that the Fractional Zener (FZ) and Fractional Kelvin (FK) models effectively represented their viscoelastic properties. These models may help classify cancer cells by their mechanical characteristics, though further research is needed to understand the implications of each model's parameters in relation to the cells' physical properties.
8) It’s not every day we find ourselves reading papers from the Journal of Experimental Botany but in Cell wall fucosylation in Arabidopsis influences control of leaf water loss and alters stomatal development and mechanical properties we learned this year how multifrequency AFM can be applied to plant cell walls in the Thale Cross (Arabidopsis) to measure nanomechanical properties. Properties such as the stiffness and elastic modulus can be used to understand plant development and water retention.
Multifrequency atomic force microscopy measurements show that viscoelastic properties differ in sfr8 Arabidopsis plant guard cell walls, but the time response remains the same. Taken from https://academic.oup.com/jxb/article/74/8/2680/7009203?guestAccessKey=30e90236-eda6-4dcf-b169-67ae1b0c813eT
9) We are suckers for High Speed AFM movies, especially with high resolution, and this paper Imaging single CaMKII holoenzymes at work by high-speed atomic force microscopy from the world-renowned high speed AFM lab in Kanazawa really delivers! Their study uses AFM to see what is happening when a mammalian protein (Ca2+/calmodulin-dependent protein kinase II (CaMKII)) that is crucial for the process of synaptic plasticity gets activated. AFM enabled them to see the protein’s unique structural features and reactions to certain molecular processes which might explain why neuronal functions differ between mammals and other species. This difference could be important for understanding how complex brain functions, like learning and memory, have evolved.
The CaMKIIα holoenzyme with pT286 in the Ca2+/CaM-bound state retains its extended structure and high mobility. Sequential HS-AFM images (3.3 frames/s) of Ca2+/CaM-bound rat CaMKIIα with ATP. Taken from https://www.science.org/doi/full/10.1126/sciadv.adh1069
10) In 3D Imaging and Quantitative Subsurface Dielectric Constant Measurement Using Peak Force Kelvin Probe Force Microscopy researchers identified a new means of nanoscale analysis that provides detailed images of a material's subsurface as well as it’s surface by combining different signals during the imaging process. This method makes it possible to measure a material’s mechanical properties, and assess its electrical characteristics including surface potential and dielectric properties. This new method could provide valuable insights in advanced technologies ranging from nano-biotechnology, molecular electronics, and 2D nanomaterials to semiconducting and piezo–electric devices for electronics and energy conversion applications.
11) Now the fact this one used our SCOUT 70 probes simply adds another level of joy for us in reading about this research! With Coupled dissolution-precipitation and growth processes on calcite, aragonite, and Carrara marble exposed to cadmium-rich aqueous solutions yet again our interest in AFM takes us into scientific worlds we wouldn’t necessarily be exploring otherwise, specifically in this instance chemical geology. The research uses AFM to observe how cadmium affects the way calcium carbonate dissolves and forms new minerals under different conditions with potentially interesting applications for use in environmental remediation. The process they observed could be used to remove cadmium, a harmful pollutant, from contaminated water, offering a method to clean up and protect the environment from this toxic substance, when it occurs for example in drinking water.
12) Coupled mechanical oscillator enables precise detection of nanowire flexural vibrations demonstrates a new method for improving how we detect very small movements and vibrations in nanowires (NWs), which are extremely thin wires, just a few atoms wide. Current methods for measuring how nanowires move or oscillate have drawbacks that can overheat the wire or affect the measurements. By linking the nanowire to a cantilever and then using a scanning probe microscopy to measure the cantilevers movements, the researchers were able to indirectly measure how the nanowire vibrates.
So many of these papers were a joy to read because they are taking the technique of AFM in new directions, developing the capabilities of AFM and breaking new frontiers in the process. There are undoubtedly many many more brilliant papers that we didn’t reference in this post – and we welcome you sending those ones on to us! Not only do we love reading them, we like to share the love by posting them across our social media channels. Send us your favourite papers at community@nunano.com
And with that we say goodbye to 2023 and wish you all a peaceful holiday season. We look forward to more marvellous adventures in AFM with you all in 2024!
References
Quantum Simulator to Emulate Lower-Dimensional Molecular Structure E. Sierda, X. Huang, D. I. Badrtdinov, B. Kiraly, E. J. Knol, G. C. Groenenboom, M. I. Katsnelson, M. Rösner, D. Wegner & A. A. Khajetoorians (2023) Science 380 (6649): 1048–52
The Quantum Twisting Microscope A. Inbar, J. Birkbeck, J. Xiao, T. Taniguchi, K. Watanabe, B. Yan, Y. Oreg, Ady Stern, E. Berg & S. Ilani. (2023) Nature 614 (7949): 682–87
Atomically Resolved Defects on Thin Molybdenum Carbide (α-Mo2C) Crystals S. A. Sumaiya, I. Demiroglu, O. R. Caylan, G. C. Buke, C. Sevik & M. Z. Baykara. (2023) Langmuir: The ACS Journal of Surfaces and Colloids 39 (31): 10788–94.
Intramolecular Force Mapping at Room Temperature T. Brown, P. J. Blowey, J. Henry & A. Sweetman (2023) ACS Nano 17 (2): 1298–1304
A pentameric TRPV3 channel with a dilated pore S. Lansky, J. M. Betancourt, J. Zhang, Y. Jiang, E. D. Kim, N. Paknejad, C. M. Nimigean, P. Yuan & S. Scheuring (2023) Nature 621, 206–214
Enhanced Surface Nanoanalytics of Transient Biomolecular Processes A. Miller, S. Chia, Z. Toprakcioglu, T. Hakala, R. Schmid, Y. Feng, T. Kartanas, et al. (2023) Science Advances 9 (2): eabq3151
Methodologies and Models for Measuring Viscoelastic Properties of Cancer Cells: Towards a Universal Classification L. Ovalle-Flores, M. Rodríguez-Nieto, D. Zárate-Triviño, C Rodríguez-Padilla, and J. L. Menchaca. (2023) Journal of the Mechanical Behavior of Biomedical Materials 140 (April): 105734.
Cell Wall Fucosylation in Arabidopsis Influences Control of Leaf Water Loss and Alters Stomatal Development and Mechanical Properties P. E. Panter, J. Seifert, M. Dale, A. J. Pridgeon, R. Hulme, N. Ramsay, S. Contera & H. Knight (2023) Journal of Experimental Botany 74 (8): 2680–91
Imaging Single CaMKII Holoenzymes at Work by High-Speed Atomic Force Microscopy S. Tsujioka, A. Sumino, Y. Nagasawa, T. Sumikama, H. Flechsig, L. Puppulin, T. Tomita, et al. (2023) Science Advances 9 (26): eadh1069
3D Imaging and Quantitative Subsurface Dielectric Constant Measurement Using Peak Force Kelvin Probe Force Microscopy K. Khaled, A. Assoum, P. De Wolf, F. Piquemal, A. Nehmee, A. Naja, T. Beyrouthy & M. Jouiad (2023) Advanced Materials Interfaces, 2300503 https://doi.org/10.1002/admi.202300503
Coupled Dissolution-Precipitation and Growth Processes on Calcite, Aragonite, and Carrara Marble Exposed to Cadmium-Rich Aqueous Solutions J. Maude, C. V. Putnis, H. E. King & F. Renard (2023) Chemical Geology 621 (March): 121364
Coupled mechanical oscillator enables precise detection of nanowire flexural vibrations M. Sharma, A. S. Prasad, N. H. Freitag, B. Büchner & T. Mühl (2023) Communications Physics 6 352