Screening colorectal tumor-associated fibroblasts using dual-channel THz biosensor

In clinical oncology, label-free identification of colorectal tumor-associated fibroblast (CAF) subtypes is challenging. In this work, a terahertz (THz) metasurface exhibiting dual channels of probation, quasi-bound states in the continuum (q-BICs) and electromagnetically induced transparency (EIT), is used to screen CAF subtypes in colorectal tumors. When impinging light is polarized along x axis, the pro-tumorigenic myofibroblasts (myCAFs) cause frequency red-shift of q-BIC resonances compared to intestinal epithelial cells, while anti-tumorigenic antigen-presenting CAFs (apCAFs) result in blueshift. Similarly, for EIT modes, when light is polarized along the orthogonal polarization, myCAFs result in a frequency red-shift while apCAFs result in blueshift. These frequency shifts are attributed to the dielectric environment variation due to the surface hall-marks of CAFs. To validate our results, we conducted flow cytometry and gene expression analyses that confirmed distinct hallmarks of myCAFs and apCAFs, consistent with the resonance frequency shifts observed in THz metasurface measurements. Our findings demonstrate a label-free and cost-effective method for screening CAF subtypes using two-parameters-q-BICs and EIT-which can help speed up cancer diagnosis.