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NANO2021-Nanoteknologi og nye materiale

On-chip Raman-spectroscopy of extracellular vesicles

Alternative title: Optisk brikke for Raman-spektroskopi av vesiklar frå celler

Awarded: NOK 12.1 mill.

Introduction and summary: Extracellular vesicles (EVs) are tiny particles released from biological cells (diameter approx. 100 nm). EVs can circulate in the body, while cells are mostly fixed in tissue. EVs are considered a mechanism for communications between cells, allowing cells to exchange proteins, lipids and genetic material. Elevated levels of EVs have been associated with several disease states such as atherosclerosis, diabetes, cancer, arterial cardiovascular diseases and venous thromboembolism. EVs thus contain information about the cells in the body. This information can be revealed by characterising the EVs in a drop of blood. New methods to characterise and analyse EVs are essential to understand the biological functions of these vesicles, and to develop new clinical methods involving their use and/or analysis. The aim of the project is to develop high throughput chemical analysis of EVs and facilitate medical research on EVs using the proposed new system. An optical chip will be developed to characterise the EVs using Raman-spectroscopy. One or a few EVs will be held by optical forces for long enough to analyse them. This will be done at several sites on the chip, using light from a single laser. The chip will be connected with a bundle of optical fibres to an optical spectrometer, that will acquire the Raman-spectra from the EVs. Based on the Raman-spectra, chemical information about the EVs can be obtained. The system will allow many EVs to be analysed at the same time, and thus make it a high throughput system. Two research groups in medical biology participate in the project and will use the system developed for research on venous thromboembolism and novel antimicrobial molecules. Status per November 2022: The project is now ready for the first, major test: The optical chip is ready with waveguides and a slit for trapping EVs, a high-power laser has just arrived, the measurement setup has been tested and the analysis method is ready. The next weeks will thus be interesting and critical. There will probably be a new round with production of the chip, with optimalisation of the current design and also a new design. Based on this, it is expected that the main hypothesis of the project will be tested in December 2022 and the start of 2023. This is somewhat delayed due to late delivery of the laser (approx. 8 months). Based on the above, the project is mostly on schedule. But one activity will be cancelled: analysis of EVs from bacteria (milestone no. 6). This is because the biologist involved has left UiT. A post-doc, Marek Vlk, starteed on the project 1st Dec. 2021. He is very important for production of the optical chip and is an expert on processes and methods for this, using NTNU Nanolab. However, he has got an MSCA Global fellowship, and will thus leave for Stanford University on 1st Feb. 2023. The aim is that Marek will do much of the fabrication-tasks before he leaves, including some 250 nm thin ‘hold your breath’ structures. It will thus be an intense period before he leaves. The rest of the funding for the position has been announced as a two-year post-doc. Unfortunately, the only qualified applicant withdrew, and the position will be announced again in Jan/Feb. 2023. The two PhD-students on the project are reasonably on schedule. Both have taken the necessary courses. Rabiul Hasan is submitting his third paper this week. A fourth, experimental paper is planned for March. Rabiul is in parallel going to write his thesis and finish by June 2023. The other PhD-student, Mathias N. Jensen, has almost finished his first article and one more is planned. He has also published two articles based on his master-degree. There might be a shortage of time for finishing in October 2023.

Extracellular vesicles (EVs) are bilayer membrane vesicles released from various cells into their surroundings. EVs include exosomes (30-100 nm in diameter) and microvesicles (100-1000 nm) and express surface antigens specific of parental cells. EVs are considered a mechanism for intercellular communications, allowing cells to exchange proteins, lipids and genetic material. Elevated plasma levels of EVs have been associated with several disease states such as atherosclerosis, diabetes, cancer, arterial cardiovascular diseases and venous thromboembolism. New methods to characterise and analyse EVs are essential to understand the physiological and pathological functions of these vesicles, and to develop new clinical methods involving their use and/or analysis. The aim of the project is to develop high throughput chemical analysis of EVs and facilitate medical research on EVs using the system developed. Dielectric optical waveguides will be tapered down to sub-micron tips. A tightly confined and standing wave between two tips will be used for optical trapping and Raman-spectroscopy of EVs. This will be done at several sites on the chip simultaneously. As a very small amount of the incident light is ‘consumed’ by each particle, the incident light can be re-used at several sites in series, without increasing the input power. This is, to the best of our knowledge, a completely new concept. By also doing this in parallel, a 2D array of trapping sites can be made, but this time by multiplying the input power. The Raman-scattered light will be collected by waveguides with high numerical aperture and directed to a 1D fibre array, which connects the chip with a multichannel spectrometer. Two research groups in medical biology participate in the project and will use the system developed for research on venous thromboembolism and novel antimicrobial molecules.

Funding scheme:

NANO2021-Nanoteknologi og nye materiale