As selected by the NuNano team and the AFM Community…

Over the past few weeks at NuNano HQ we’ve been chatting about AFM papers that have caught our attention this year. As ever the breadth and depth of the research happening around the world using AFM is pretty breath-taking. In our selection below we’re really only scratching at the surface of what’s been happening - but what a surface! In no particular order here are 8 interesting AFM papers from around the globe that made our Nice List this year…

1) First up is research by Dr Marcos Penedo et al. and the team at the Nano Life Science Institute (WPI-NanoLSI), Kanazawa University, in Japan. Their paper ‘Visualizing intracellular nanostructures of living cells by nanoendoscopy-AFM’ - (2021) Science Advances Vol 7 (52) caught the eye of NuNano Applications Engineer Jamie Goodchild who voted it one of the best papers of the year. You might notice it was actually published in December 2021 but right at the end and so missed out on being included in our list last year.

What grabbed Jamie’s attention about this research was their performance of ‘nano-endoscopy’ on a living cell. Not only did they put an AFM tip through a living cell to image the inner side of the cell membrane, they managed to do this while keeping the cell viable (i.e. alive!). To quote Jamie ‘really cool stuff’.

2) Moving our attention to Spain and the work of Dr Jaime Carracedo-Cosme et al. from the Condensed Matter Physics Center (IFIMAC), Autonomous University of Madrid, we found their paper ‘QUAM-AFM: A Free Database for Molecular Identification by Atomic Force Microscopy’ (2022) Journal of Chemical Information and Modeling, 62 (5), interesting because we love a free AFM based resource that can help the wider community of researchers in the work they are doing.

Specifically the database comprises the largest data set of simulated atomic force microscopy (AFM) images generated from a selection of 685,513 molecules that span the most relevant bonding structures and chemical species in organic chemistry.

Comparison of static AFM force images. Taken from https://pubs.acs.org/doi/full/10.1021/acs.jcim.1c01323

The database contains 165 million images with a resolution of 256 × 256 pixels. The 3D stacks are especially appropriate to tackle the goal of the chemical identification within AFM experiments by using deep learning techniques. The data provided for each molecule include, besides a set of AFM images, ball-and-stick depictions, IUPAC names, chemical formulas, atomic coordinates, and map of atomic heights.

3) Our third paper is by Dr Brisa Pena and the team at the Cardiovascular Institute & Adult Medical Genetics, University of Colorado, USA, who have published their research using AFM on Cardiomycocyte Cells: Cellular Biomechanic Impairment in Cardiomyocytes Carrying the Progeria Mutation: An Atomic Force Microscopy Investigation - (2022) Langmuir, 38, (48).

The focus of the research is on using AFM to understand a rare genetic heart disorder that prematurely ages the vascular system which can lead to heart failure. We loved the multidisciplinary approach the authors took with this work, including the valuable contribution that AFM continues to make in the world of cell research.

It also reminded NuNano Ops Manager Dr Joanna Evangelides of her work using AFM during her own PhD!

4) Camila Leiva-Sabadini et al. at the School of Dentistry, The Pontifical Catholic University of Chile, Chile gave us something to get our teeth into (groan, well, it is the season of bad cracker jokes…) in their paper on the ‘Ultrastructural characterisation of young and aged dental enamel by atomic force microscopy’, (2022) Journal of Microscopy, 288.

Whilst AFM has been used already to characterise tooth enamel, with great results, this is the first paper to document the use of high-resolution AFM to explore the changes in tooth enamel structure that occur due to ageing with nanoscale resolution.

Ultrastructure of superficial dental human enamel using AFM. Taken from https://onlinelibrary.wiley.com/doi/full/10.1111/jmi.13126

Whilst the research was conducted on a small sample set, initial results look promising for further research in this area. That the work was undertaken using NuNano SCOUT 350 RAu probes only adds to our pleasure in reading the paper!

5) Whilst AFM is perhaps most accurately described as the best supporting actor rather than the main focus in our next paper by Dr Riccardo Fusi et al. at the School of Biosciences, University of Nottingham, UK, it was for that very reason we felt it was important to include it in our list. AFM underpins so much research and we would be the last people to let that go by unheralded.

The paper ‘Root angle is controlled by EGT1 in cereal crops employing an antigravitropic mechanism’ (2022) PNAS, Vol 119 (31) looks at the genetic identifier that impacts the root angle of cereal crops, with the notion that crops with steeper root angles achieve better access to nutrients and water from the soil and has interesting ramifications for food security.

You can see results from the AFM work in Figure 4G and in the appendix. The associated AFM work was conducted by Dr Jacob Pattem from the School of Biosciences.

6) Understanding the impact of proteins in neurodegenerative disorders like Alzheimer’s disease have been in the news a lot lately and our next paper highlights the way in which AFM has been used to further this work.

Dr Olena Synhaivska et al. at the Transport at Nanoscale Interfaces Laboratory, Swiss Federal Laboratories for Materials Science and Technology, Switzerland published their paper ‘Single-Particle Resolution of Copper-Associated Annular α-Synuclein Oligomers Reveals Potential Therapeutic Targets of Neurodegeneration’, (2022) ACS Chemical Neuroscience, 13 (9), in April this year.

Their findings emphasised the importance of targeting particular amyloid proteins not only for therapeutic intervention but also as potential biomarkers for early detection. We’re proud as punch that our Scout 70 HAR RAu probes were used in the course of this research.

7) Sticking with the medical theme, our seventh choice is actually a chapter from a book rather than a paper - Antibiotic resistance - Chapter 23 - Atomic force microscopy as multifunctional microbial imaging and characterization platform – by Dr Marta Woźniak-Budych at the NanoBioMedical Centre, Adam Mickiewicz University, Poland, made it to our list because antibiotic resistance is a vitally important issue, and AFM can play its part.

Various techniques used for microbial identification and bioimaging. Taken from https://www.sciencedirect.com/science/article/pii/B9780128234266000036#f0035

Here, they describe how AFM can be used for single molecule and single cell imaging, looking at bacteria and antibiotic resistance. As the chapter states, AFM demonstrates great potential to provide detailed biological characterization with nanoscale resolution, in the field of bacteriology, virology, mycology, and cell biology. Developments and modifications of AFM in the past three decades have enabled routine imaging of single molecules such as nucleic acids and proteins. Further developments, including novel AFM imaging modes and AFM in combination with other techniques (e.g. IR and Raman), allow more advanced studies capable of obtaining structural, mechanical and chemical information on bacteria at the nanoscale.

8) Our final paper brought a veritable ‘sparkle’ to the office (groan, look it’s nearly over!) when we came across this in early December. In ‘Pinaceae Fir Resins as Natural Dielectrics for Low Voltage Operating, Hysteresis-Free Organic Field Effect Transistors’ (2022) Advanced Sustainable Systems, Vol 6 (10), Dr Jelena Ivić et al. at Johannes Kepler University Linz, Austria used NuNano’s Spark 350 Pt probe in the analysis of two natural resins, silver fir and Rocky mountain fir, which demonstrate robust dielectric properties.

We were particularly taken by the innovative work going into finding sustainable alternatives for the development of electronics and sensors. The paper is beautifully written and an engaging read. And…well, what could be more Christmassy than an AFM paper that uses NuNano Spark 350 Pt probes in the analysis of Christmas tree resin?!

There have been heaps of AFM papers this year on an amazing variety of topics. If you’ve got a particular favourite you’d like to share with us, do get in touch via community@nunano.com and we will share it via social media and in our ‘AFM Papers’ section of our AFM Community News section of our January newsletter.

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