Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 150257

150257 - Photoacoustic-Brillouin Microscopy for Multimodal Mechanical Imaging of Tumor Growth 

Tumor tissues are usually harder than surrounding healthy tissues, leading to a different microenvironment for cancer cells inside. Since the behaviors and functions of cells are regulated by physical cues from their microenvironment, emerging research has suggested that the altered mechanics of tumor tissue plays a crucial role in the progression of metastatic cancers. To understand the relationship between the properties of the microenvironment and tumor growth, it is essential to quantify these mechanical properties with high spatial resolution in three dimensions. However, existing mechanical testing tools are mostly contact-based and invasive, making such measurement highly challenging. This Faculty Early Career Development (CAREER) project aims to address the current technical challenge by developing an optical technology named photoacoustic-Brillouin microscopy (PABM), which can measure the mechanical properties of cancer cells and their microenvironment in a non-contact, non-invasive, and high-resolution manner. In concert with the research goal, this project will develop educational modules to promote the dissemination of the innovative Brillouin technology and to stimulate a lasting interest in biophotonics for high school, undergraduate, and graduate students.

Current mechanical testing toos such as atomic force microscopy and micropipette aspiration are contact based: during experiment, the sample needs to be physically contacted and deformed. This makes the measurments invasive and often limit to cells in 2D culture condition. Optical confocal Brillouin microscopy has been recently demonstrated as a promising non-contact mechanical testing tool. Brillouin microscopy utilizes a laser beam to probe the mechanical properties of biological materials, making it non-contact, non-invasive, and label free. However, due to the lack of knowledge on refractive index and density of the sample under test, existing Brillouin microscopy is mostly used to estimate the relative mechanical change, rather than to provide an absolute measurement of mechanical modulus, making it inapplicable for heterogeneous tumor microenvironment, benchmarking, and comparison across studies. In this project, a novel optical technique named PABM will be developed based on the colocalized excitation of scattered Brillouin light and time-resolved photoacoustic signals. In addition to directly quantifying mechanical modulus, the PABM can provide complementary contrast mechanisms, including stiffness, optical absorption, and acoustic speed. This capability will enable a comprehensive understanding of heterogeneous processes in tumor growth. Taken together, the PABM addresses a significant gap in current cancer research methodologies. The new data and insights gained from this technology holds a unique potential to advance a wide range of research in both biophotonics and cancer diseases.

Presenting Author: Jitao Zhang Wayne State University

Presenting Author Biography: Dr. Jitao Zhang is an assistant professor in the Department of Biomedical Engineering at Wayne State University. Before joining Wayne State, he spent six years in Fischell Department of Bioengineering at the University of Maryland, College Park, first as postdoc and then as assistant research professor. Prior to Maryland, he briefly worked at the University of Arizona as a postdoc, where he developed optical spectrometer and devices. He obtained his Ph.D. in optical engineering from Tsinghua University, Beijing, China. Jitao has been a recipient of several awards, including the Doctoral Dissertation Excellence Award, the Excellent Youth of China Instrument Society scholarship, the Marcy Speer Award for postdoc, the NIH Mentored Quantitative Research Career Development Award (K25), and the NSF CAREER Award. He has been granted 3 patents on Brillouin technique. He serves on the editorial board of the journal Scientific Reports and is a member of the program committee for the SPIE Photonics West Conference. He is also a guest editor for the Journal of Physics: Photonics.

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