Advancements towards Construction of a Novel Nanometer-resolution MeV-STEM for Imaging Thick Frozen Biological Samples

Isabella Santos^*
*Correspondence: Isabella Santos, Department of Nanotechnology, University of Melbourne, Parkville VIC 3010, Australia, Email:

Keywords

Biological samples • MeV-STEM • Electrons

Introduction

The ability to visualize biological samples at nanometer resolution is crucial for understanding their structural and functional properties. Traditional electron microscopy techniques, such as Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM), have been invaluable tools in this regard. However, imaging thick biological samples with these techniques often results in significant radiation damage and poor contrast due to electron scattering. In recent years, there has been a growing interest in the development of high-energy electron microscopy techniques, such as MeV-STEM, for imaging biological samples. These techniques offer several advantages over conventional electron microscopy, including reduced radiation damage and increased penetration depth. In this article, we discuss the advancements towards the construction of a novel MeV-STEM system specifically designed for imaging thick frozen biological samples with nanometer resolution [1].

Literature Review

MeV-STEM combines the principles of both TEM and SEM, utilizing a focused beam of high-energy electrons to scan across a sample and generate images with nanometer resolution. Unlike conventional electron microscopy, which typically operates at energies in the range of a few hundred kilo-electron Volts (keV), MeV-STEM operates at energies in the mega-electron volt (MeV) range [2]. One of the key advantages of MeV-STEM is its ability to penetrate thick samples with minimal radiation damage. High-energy electrons have a much larger penetration depth compared to low-energy electrons, allowing them to traverse through thicker specimens without significant scattering or absorption. This property makes MeV-STEM particularly well-suited for imaging thick biological samples, such as frozen tissues or cells.

Furthermore, MeV-STEM offers improved contrast and signal-to-noise ratio compared to lower energy techniques. This is due to the reduced elastic scattering of high-energy electrons, which results in clearer images with higher contrast. Additionally, the higher energy of the electrons enables the use of advanced imaging modes, such as energy-loss spectroscopy and electron tomography, further enhancing the capabilities of MeV-STEM for biological imaging [3]. While MeV-STEM holds great promise for imaging thick frozen biological samples, several challenges need to be addressed to realize its full potential. One major challenge is sample preparation, particularly the preservation of biological structures during freezing. Traditional methods of sample preparation, such as chemical fixation and dehydration, can lead to structural distortions and artifacts [4].

Discussion

To overcome these challenges, researchers have developed novel techniques for cryopreservation, such as high-pressure freezing and freeze substitution. These methods involve rapidly freezing the samples to cryogenic temperatures to preserve their native structure. By combining these cryopreservation techniques with MeV-STEM imaging, researchers can obtain high-resolution images of biological samples in their native state, free from artifacts caused by chemical fixation or dehydration [5].

Another challenge in imaging thick frozen biological samples is the development of suitable detectors capable of capturing high-resolution images with minimal noise. Traditional detectors used in electron microscopy, such as Charge-Coupled Devices (CCDs) and scintillation detectors, may not be well-suited for MeV-STEM imaging due to their limited dynamic range and sensitivity to high-energy electrons [6]. To address this challenge, researchers are exploring the use of novel detector technologies, such as direct electron detectors and hybrid pixel detectors, which offer improved sensitivity and signal-to-noise ratio at MeV energies. These detectors are capable of detecting single electrons with high efficiency, making them ideal for imaging biological samples with MeV-STEM.

Conclusion

The construction of a novel MeV-STEM system for imaging thick frozen biological samples with nanometer resolution represents a significant advancement in the field of electron microscopy. By leveraging the unique properties of high-energy electrons, such as reduced radiation damage and increased penetration depth, this system holds great promise for revolutionizing our understanding of biological structures at the nanoscale. Through the development of advanced cryopreservation techniques and novel detector technologies, researchers are overcoming the challenges associated with imaging thick frozen biological samples. As these advancements continue to progress, MeV-STEM is poised to become a powerful tool for studying biological processes at the molecular level, opening up new opportunities for biomedical research and drug discovery.

In conclusion, the ongoing advancements towards the construction of a MeV-STEM system for imaging thick frozen biological samples represent a significant step forward in the field of electron microscopy, with the potential to drive transformative discoveries in biology and medicine.

Acknowledgement

None.

Conflict of Interest

None.

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