How Can Nanotechnology Help Microscopy?

The science, engineering, and technology that is conducted at the nanoscale, which ranges from 1 to 100 nm, is commonly referred to as nanotechnology1. Materials at the nanoscale level exhibit various desirable physicochemical properties, some of which can include increased strength, lighter weight, greater control of light spectrum, as well as higher chemical reactivity as compared to their bulk counterparts.

The heightened research conducted on nanotechnology over the past several years has supported the development of a myriad of potential applications in almost every area of science.

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Applications of Microscopy

Although microscopic techniques have been used for hundreds of years, modern-day technology has allowed this area to expand significantly in both the types of microscopy that have been developed, as well as the potential applications that can incorporate these advanced microscopic techniques. The applications of microscopy can be found in a wide range of industries, many of which include biological and material sciences purposes. In particular, microscopic techniques have become indispensable tools in several areas of modern medicine including diagnostic and pathology.

Nanoscale Microscope with Near-SEM Resolution

As the field of nanotechnology continues to grow, scientists have begun exploring the various ways in which they can exploit and apply this advancing field to the improvement of microscopy. For example, researchers from the University of Missouri have recently published in Nanoscale their work in developing a novel nanoscale microscope that is expected to be significantly cheaper and more accessible than existing electron microscopes2,3. This work was largely inspired by the limitations associated with traditional optical microscopes. To this end, since an optical microscope uses visible light from a light source and a series of lenses to magnify the specimens, its resolution is often determined by the wavelength of visible light. As a result, researchers are unable to obtain resolutions higher than 200 nm with optical microscopes3.

As a result of this limitation, scientists have traditionally looked to electron microscopy (EM) techniques that are based on the principle of using a beam of electrons generated by an electron gun to create the image of the specimens. As a result of the wavelength of electrons being 100,000 times shorter than the wavelength of the visible light, higher magnification images can be acquired while simultaneously maintaining an extraordinary resolving power. While the advantages of EM techniques are evident, there is often a considerable amount of time-consuming sample preparation and expensive processing that is required when using EM.

In an effort to resolve these issues, Dr. Gangopadhyay’s team at the University of Missouri were able to achieve resolutions down to 65 nm through the use of surface plasmon resonance (SPR). SPR involves visible light that is focused onto a specialized surface consisting of a repeating metallic grating. Through this interface, the resonance that occurs between certain incident photons and the oscillating surface electrons releases a plasmon wave that can absorb the resonant frequency of light2,3. This absorption pattern can be measured through the use of a detector.

In their design, the University of Missouri team utilized this technology, which can is a relatively inexpensive tool that is often used during the manufacturing of HDDVD and BlueRay discs, to create plasmonic grating on microscopic slides. Through this integration, the researchers successfully developed a novel nanoscale microscopy technique that is significantly more affordable than electron microscopy2,3. To create localized SPR and allow for the simultaneous imaging of larger areas, Dr. Gangopadhyay’s team used glancing angle deposition (GLAD) to create nanoprotrusions and nanogaps in combination with the gratings. This inexpensive nanoscale microscopy technique has the potential to be used in a wide variety of applications including diagnostics and material sciences, especially in developing countries2,3.

Spider Silk to Create Microscope Superlens

Researchers at Bangor University, in collaboration with the University of Oxford, have used nanotechnology to create a microscope superlens that can extend the resolution obtained with traditional light micrscopes4. By applying dragline silk, which is a naturally occurring material secreted by the golden web spider, to the surface of the sample, the researchers found that magnification capabilities increased by an additional 2-3 times4. The team demonstrated this effect by viewing the details of a microchip and blue-ray disk, which was previously invisible when analyzed by optical microscopes. This Bangor team believes that the naturally cylindrical spider silk will offer robust and economic advantages in a wide variety of applications in the near future.

References

“What is Nanotechnology?” – Nano.gov

“Engineers Use Spider Silk to Create a Microscope Superlens” – Engineering.com

Chen, B., Wood, A., Pathak, A., Mathai, J., Bok, S., Zheng, H., et al. (2016). Plasmonic gratings with nano-protrusions made by glancing angle deposition for single-molecule super-resolution imaging. Nanoscale 24(8); 12189-12201. DOI: 10.1039/C5NR09165A.

Monks, J. N., Yan, B., Hawkins, N., Vollrath, F., & Wang, Z. (2016). Spider Silk: Mother Nature’s Bio-Superlens. Nano Letters 16(9); 5842-5485. DOI: 10.1021/acs.nanolett.6b02641.

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Written by Benedette Cuffari After completing her Bachelor of Science in Toxicology with two minors in Spanish and Chemistry in 2016, Benedette continued her studies to complete her Master of Science in Toxicology in May of 2018. During graduate school, Benedette investigated the dermatotoxicity of mechlorethamine and bendamustine, which are two nitrogen mustard alkylating agents that are currently used in anticancer therapy.