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Leaky waveguide analysis for real time analysis of cellular chemotaxis and secretome

Primary Supervisor: Dr Ruchi Gupta, School of Chemistry

Secondary supervisor: Dr Melissa Grant

PhD project title: Leaky waveguide analysis for real time analysis of cellular chemotaxis and secretome

University of Registration: University of Birmingham

Project outline:

Background: Cellular chemotaxis and secretome is fundamental to health. For example, in the immune response neutrophils are the most abundant cell in circulation in humans and are the first line of defence against invading micro-organisms, arriving first at the site of an injury. Neutrophils follow a chemoattractant gradient, produced by either host or microbes, to move to the area where they are needed. Once neutrophils arrive at the site of injury, they secrete a range of proteins. Extensive research has demonstrated that the migration and secretome of neutrophils change with age, disease, time, and type of stimulation (e.g., from our group [1-4]).

We have utilised video microscopy in the past and Boyden chambers to explore chemotactic response of neutrophils. However, these methods are either very laborious with limited throughput or have high throughput but provide limited information on how the neutrophils move. Furthermore, no information is obtained on the secretome of neutrophils.

The aim of this project is to develop a platform technology based on leaky waveguides (LWs) for real time imaging of movement of cells (more specifically, neutrophils) while simultaneously measuring their secretome.

Methodology:

Neutrophil cells will be isolated to generate biological samples for developing LWs [4] in the following ways:

  • Study migration of cells: LWs comprise of a few micron thick hydrogel film deposited on a glass substrate. As shown in Figure 1 (a), we will use the evanescent field of light propagating in these hydrogel films to illuminate cells present on top of hydrogel films. As cells present on top of the hydrogel films will scatter light, they will appear as bright spots in the images captured by a camera placed underneath a trapezoidal prism [5]. The images will be captured in real-time to study migration of cells. Suitable proteins such as serum albumin may be adsorbed/chemically attached to hydrogel films to allow cells to move freely. A microfluidic gradient generator flow cell will be mounted on top of the hydrogel film to study the migration of cells in response to different types of signalling molecules and their concentrations [6].
  • Quantify secretome components of cells: As shown in Figure 1 (b), in this project, we will immobilise antibodies towards secretome components of cells in hydrogel films. The binding of secretome components to antibodies will cause the resonance angles of LWs to change. The resonance angles will be monitored to determine the concentration of the secretome components of cells [7]. Cells may be cultured in-situ in the microfluidic flow cell mounted on top of LWs so that spatial and temporal profiles of secretome components produced by cells can be studied.

Figure 1: LWs for (a) studying migration and (b) quantifying secretome of cells

References:

  1. M. Roberts et. al., Impaired Neutrophil Directional Chemotactic Accuracy in Chronic Periodontitis Patients, Journal of Clinical Periodontology, (2015), 1.
  2. M. Roberts et. al., Characterization of Neutrophil Function in Papillon-Lefèvre Syndrome, Journal of Leukocyte Biology, (2016), 433.
  3. M. Roberts et. al., Impact of Bariatric Surgical Intervention on Peripheral Blood Neutrophil (PBN) Function in Obesity, Obesity Surgery, (2018), 1611.
  4. Gupta et. al., Leaky Waveguides (LWs) for Chemical and Biological Sensing − A Review and Future Perspective, Sensors and Actuators B, (2020), 128628.
  5. Zourob et. al., Bacteria detection Using Disposable Optical Leaky Waveguide Sensors, Biosensors and Bioelectronics, (2005), 293.
  6. Ishida et. al., Investigation of the Influence of Glucose Concentration on Cancer Cells by Using a Microfluidic Gradient Generator without the Induction of Large Shear Stress, Micromachines, (2016), 155.
  7. R. Andrew et. al., Label-free Leaky Waveguide for VEGF Detection, MicroTAS, (2018), 940.

BBSRC Strategic Research Priority: Understanding the Rules of Life: Immunology

      Techniques that will be undertaken during the project:

      The student will work both in Drs Gupta and Grant labs.

      The student will gain experience in primary cell isolation and functional neutrophil assays. Equally, the student will receive basic training in material and synthetic chemistry, bioconjugation, and fabrication and characterisation of LWs. The characterisation of LWs will provide exposure to optical instrumentation, and the student will build skills in image processing and data analysis.

      Contact: Dr Ruchi Gupta, University of Birmingham