Investigators: Zahid Yaqoob, Peter T.C. So, and Conor L. Evans

The Laser Biomedical Research Center (LBRC) has been one of the leaders in interferometric microscopy, including wide-field quantitative phase microscopy (QPM), tomographic phase microscopy (TPM), and depth-resolved reflection phase microscopy with applications in label-free quantification of cellular morphology (including height, footprint, surface area, and volume), cell biomechanics, cell dry mass, and cell growth and division. During the current cycle, the LBRC aims at pushing interferometric imaging technology forward in the following three directions:

1. 3D-resolved biomechanical assays

Cell mechanics plays an important role in a number of complex biological processes including but not limited to metabolism, cell signaling, growth, and wound healing. The most common approaches to assess cellular rheology including atomic force microscopy (AFM), optical and magnetic tweezers, pipette aspiration, and electric field deformation are invasive and thus are not suitable especially for nuclear biomechanical studies in intact cells. To this end, interferometric microscopy is an appealing approach to quantify cell biomechanics by measuring nanometer scale axial motions of the cell membrane. The LBRC has successfully used transmission-type interferometric microscopy techniques to study biomechanical properties of RBCs in different pathophysiological conditions. To extend this approach to complex eukaryotic cells, LBRC aims to develop a next-generation interferometric biomechanical assay based on 3D-resolved measurement of sub-nanometer-scale membrane motions to quantify plasma/nuclear membrane mechanics. read more>>

2. High-throughput 3D cytometry

Cytometry provides statistical analysis of a large population of cells. While flow cytometry enables characterizing gene and protein expression with throughput up to 100,000 cell/sec, it lacks morphological information. Image flow cytometry addresses this need by providing 3D structural information of the cell population, and has found numerous applications in biology and pharmacology. The LBRC has also been at the forefront in developing 3D-resolved image cytometry for cells and biological tissues. Today, most image cytometers are based on fluorescent contrast; however, developing label-free approaches has several advantages. For instance, interferometric microscopy based cytometers are virtually free from photodamage and allow for long-term, time-lapse imaging. Furthermore, without exogenous labels, sample preparation is easy and has minimal cytotoxicity. Finally, many biotechnology applications such as mesenchymal stem cell sorting or embryo selection for in vitro fertilization are not compatible with exogenous labels. read more>>

3. Interferometric imaging with molecular specificity

Interferometric imaging typically measures optical path length changes to provide label-free contrast for structural and functional imaging. Since molecular specific imaging remains the bedrock of modern biological research and medical diagnostics, LBRC also aims to extend the scope of interferometric measurements to additionally providing molecule-specific information of biological cells. Spectroscopic interferometric imaging frameworks based on both linear absorption, transient absorption, and photothermal signal will be developed. Successful development of these technologies will have considerable impact on studies aimed at quantifying absolute oxy- and deoxy-hemoglobin concentrations in sickle RBCs during hypoxia and high throughput detection of eumelanin vs pheomelanin distribution in skin cells. read more>>