Kanazawa NanoLSI Research Podcast: Small but mighty: Identifying nanosized molecules using atomic force microscopy

Kanazawa NanoLSI Research Podcast 

26 May 2022 

Small but mighty: Identifying nanosized molecules using atomic force microscopy 

In a recent study Mikihiro Shibata and Leonardo Puppulin at the WPI Nano Life Science Institute Kanazawa University (NanoLSI) used advanced atomic force microscopy to accurately recognize tiny cellular biomolecules. 

Learn more about their research here: WPI Kanazawa Nano Life Science Institute

https://nanolsi.kanazawa-u.ac.jp/en/research/researchers/

Original article:  https://pubs.acs.org/doi/10.1021/acsami.1c17708

Transcript of this podcast

Hello and welcome to the NanoLSI podcast. Thank you for joining us today. In this episode we will feature the latest research published by Mikihiro Shibata and Leonardo Puppulin. They are both members of the nanometrology group at the Kanazawa University NanoLSI.

The research described in this podcast was published in the American Chemical Society, Applied Materials  Interfaces, in November 2021.  

Small but mighty: Identifying nanosized molecules using atomic force microscopy

In a study recently published in the journal Applied Materials and Interfaces researchers from Kanazawa University use advanced atomic force microscopy to accurately recognize tiny cellular biomolecules. 

Biologists rely on a wide range of microscopy techniques to visualize biomolecules within biological cells. High-speed atomic force microscopy (HS-AFM) is one such example in which a sharp tip attached to a sensor is used for visualizing cells. Specifically, as the AFM tip scans the surface of a molecule, the pattern of signals it generates enables researchers to visualize the molecule’s topography. However, recognizing individual biomolecules using HS-AFM is still in its infancy. Now, researchers at Kanazawa University report on an innovative method to facilitate this by tweaking the structures of AFM tips.

The research team, led by Mikihiro Shibata and Leonardo Puppulin at the WPI Nano Life Science Institute Kanazawa University (NanoLSI), characterized a protein found on human cells known as the hepatocyte growth factor receptor (hMET).

 The researchers first attached aMD4, a synthetic molecule that latches onto hMET, to the HS-AFM tip using different sized linkers. Patterns of connections between this modified tip and single molecules of hMET were subsequently investigated. 

When hMET on a mica surface (a material typically used in HS-AFM studies) was exposed to the tip, interactions between aMD4 and the external surface of hMET were indeed observed. 

However, when multiple molecules of aMD4 and hMET were used, it was found that shorter and more flexible linkers enabled aMD4 to interact with two adjacent hMET molecules bringing them closer together. 

This observation posits practical applications in the laboratory—biologists can potentially mimic the binding of two cell surface proteins together which often leads to the induction of cellular processes. 

Next, the specificity of this tip for molecule recognition was examined. hMET and its mouse form are very similar in structure. However, the mouse form does not bind to aMD4. Thus, when the aMD4-loaded tips were exposed to both forms of the protein, activity was observed only with the human form. 

This technique could therefore be useful in the selection of specific biomolecules from a heterogenous mix as is typically seen on the cell surface.

 Lastly, the modified HS-AFM technique was applied when hMET was bound to a lipid surface mimicking the structural composition of cell membranes (its natural home). Similar interactions wer

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