Buffer optimisation for an improved cell separation using Acoustophoresis with Polystyrene particles, Jurkat, MCF-7 and DU-145 cell lines

Abstract (Swedish)

Akustophores är rörelse av partiklar/celler under inverkan av ljud. Partikel- och cell separation är en applikation som kan utföras av akustophores. Detta är en viktig teknik eftersom den kan avslöja viktig information om sjukdomar och celler och därigenom förbättra valet av behandling inom sjukvården. Genom att utnyttja ljud, så kan celler och partiklar i en lösning separeras efter deras specifika egenskaper; storlek, densitet och kompressibilitet. De två sistnämnda återfinns båda i den akustiska kontrast faktorn. Tecknet på den akustiska kontrast faktorn bestämmer riktningen på rörelsen, och är således en viktig faktor i separationen. Denna avhandling syftar till att förbättra separationen mellan celler med hjälp av Polystyrene partiklar som referens. Detta görs genom att justera egenskaperna som påverkar den akustiska kontrast faktorn, i detta fall egenskaperna hos bufferten. Genom att mäta mobiliteten hos celler och partiklar, vilket är baserad på deras banor i akustophoreschippet, kan buffertegenskaperna analyseras på ett effektivt sätt. Denna avhandling inkluderar tester med Polystyrene partiklar i olika storlekar och ett antal olika cell liner, (DU-145 (prostatacancer celler), MCF-7 (bröstcancer celler) and Jurkat (T-lymfocyt celler)). Under testerna, så blev det klart att MCF-7 cellerna erhåller en ändring i kontrastfaktorn när de är i en buffert med 10% och 20% Iodixanol, vilket möjliggör en full separation från 7.79μm Polystyrene partiklarna. Det blev också klart att egenskaperna av bufferten hade en inverkan eftersom en buffert med högre densitet påverkade separationen för samtliga cell linjer.

Abstract

Acoustophoresis is the migration of particles/cells under the influence of sound. Particle and cell separation is an application that can be performed by acoustophoresis. This is an important technique since it can reveal important information about diseases and cells and thereby possibly improve the choice of treatment in healthcare. By utilizing sound, cells and particles in a suspension can be separated due to their distinct properties such as size, compressibility and density. The last two are parameters found in the acoustic contrast factor. The sign of the contrast factor determines the direction of the migration, which is an important factor in the separation. This thesis aims to improve the the separation between cells, using Polystyrene particles as reference. This is done by adjusting properties affecting the acoustic contrast factor, in this case the buffer conditions. By measuring the mobility ratio of cells and particles, which is based on their trajectories in the acoustophoresis chip, the buffer conditions can be analysed in an efficient way. This thesis includes tests of Polystyrene particles with different sizes and three different cell lines (DU-145 (prostate cancer cells), MCF-7 (breast cancer cells) and Jurkat (T lymphocyte cells)). During the experiments, it was found out that the MCF-7 cells exerts a change in contrast factor when suspended in a buffer with 10% and 20% Iodixanol, enabling a fully separation from the 7.79μm Polystyrene particles. It was also clear that the buffer condition had an impact of the separation since a higher density medium improved the separation for all cell lines.

Popular Abstract

Buffer optimisation for an improved cell separation using Acoustophoresis

Acoustophoresis is a technique in microscale systems where sound is utilized to move particles and cells. When the channel width of the microchip is dimensioned to half a wavelength, a pressure node in the middle of the chip is created. This enables separation between particles and cells when suspended in a buffer medium. The separation is dependent on inherent properties of the particle/cell such as density and compressibility; factors contributing to the acoustic contrast factor. A positive sign of the contrast factor will create movement to the pressure node (middle) and a negative contrast factor creates movement to the pressure anti-nodes (sides) of the chip. The size is also of great importance since larger particles are affected by a greater acoustic radiation force, creating a faster movement towards the pressure node compared to smaller ones. By using different outlets in the acoustophoresis channel, cells and particles can efficiently be separated from each other based on their acoustic properties. A successful separation is desirable since it can reveal important information about diseases and different cell types, such as cancer cells and different breast cancer cell lines. This could lead to more personalized treatment in healthcare since a better understanding of how the different cell types work and behave is gained.

Further, it is shown that the buffer medium has an influence on the cell separation. This, since the buffer medium has an impact on the acoustic contrast factor, which affects the movement of the particles/cells in the chip. By measuring the mobility ratio, the trajectories of particles and cells in the chip can be predicted. Therefore, measuring the mobility ratio is an important tool when investigating how the buffer conditions affect the separation. A higher mobility ratio indicates a better separation between the different particles/cell types. For this thesis, the goal was to find a buffer media that could increase cell separation. This was done by investigating different buffer mediums and eventually calculating the mobility ratio using MATLAB. The cell lines that were studied during this thesis were MCF-7 (breast cancer cells), DU-145 (prostate cancer cells) and Jurkat (T-Lymphocyte cells). These were tested together with Polystyrene particles of different sizes and colors. The buffer medium was changed by adding different concentration of a dense medium.

The most important finding was that the buffer medium indeed had a great impact on the separation. A general trend that could be seen was that the higher density of the buffer, the better separation. Regarding the MCF-7 cells, it was observed a change in the acoustic contrast factor when using a buffer medium with both 10-and 20% Iodixanol. This indicates that there is a possibility to separate them from other cell lines, such as the DU-145 and Jurkat cells where no switch in acoustic contrast factor could be seen. From the experiments it could also be concluded that the Polystyrene particles seem to have different material properties even though they share the same composition. This would be good to further investigate since they are used a lot in research as reference.

The work in this thesis will hopefully come to use in further experiments and research. This, since more advanced knowledge about the behavior and properties for both the Polystyrene particles and the different cell lines is gained.

• author: Silversand, Lovisa
• supervisor: Thierry Baasch; Andreas Lenshof
• organization: Department of Biomedical Engineering
• course: BMEM01 20232
• year: 2023
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• language: English
• additional info: 2023-17
• id: 9141454
• date added to LUP: 2023-12-01 14:26:47
• date last changed: 2023-12-01 14:26:47