Cell-Free Fluorescent Riboswitch Biosensor to Detect CA-125 in Blood

Abstract

Endometriosis is a debilitating chronic illness characterized by the appearance of uterine tissue outside of the uterus, primarily within pelvic regions such as the ovaries or fallopian tubes, which can cause severe pain, pregnancy complications, and infertility in severe stages. Diagnosing endometriosis is only certain with laparoscopic surgery, an invasive procedure that is often inaccessibly expensive for patients, which can leave those with the condition undiagnosed and suffering for years. Due to necessity of minimally-invasive, cheaper diagnostics for endometriosis, it has been hypothesized that a biosensor targeting CA-125—a protein biomarker that correlates with the presence of endometriosis and ovarian cancer—could be used as a screening tool for endometriosis. In this study, we constructed and assembled a riboswitch-based biosensor with a fluorescent protein intended for use within a cell-free expression system (CFES) to detect for heightened levels of CA-125 in whole blood samples; tested in a CFES, fluorescence was inconsistent across samples with and without CA-125: a sample with the riboswitch & 41 nM CA-125 exhibited negligible difference compared to a sample with only the riboswitch, while a sample with the riboswitch & 410 nM CA-125 exhibited the lowest fluorescence.