Sensing changes in triglyceride concentration in blood solution using diffuse optical spectroscopy

Triglyceride (TG) is a fundamental lipid component in the bloodstream. While TG is fundamental in the body, elevated TG levels, exceeding 150 mg/dL, pose a heightened risk for multiple diseases, notably cardiovascular disease. Monitoring TG concentration is imperative to assess the efficacy of interventions aimed at lowering the TG concentration and diagnosing hypertriglyceridemia (HTG, TG concentration ≥ 200 mg/dL). Although various techniques exist for TG concentration monitoring, conventional techniques often require sample collection and/or sample preprocessing or lack portability. Recognizing the importance of TG concentration monitoring, this work endeavors to explore the viability of diffuse optical monitoring of TG concentration variations in blood. To validate the feasibility, a series of Monte Carlo simulations was performed. Then, samples containing flowing mixtures of varying TG concentrations and hemoglobin solution (for phantom experiments) or sheep blood (for ex vivo experiments) were measured using continuous-wave diffuse optical spectroscopy (CW-DOS) to experimentally demonstrate the capability of diffuse optical monitoring of TG concentration variations. Our results showed a linear decrease in CW-DOS amplitude at 885 nm with increasing TG concentration up to 800 mg/dL. In addition, in vivo mouse studies were conducted, including a control group receiving saline (n = 5) and a test group administered triton WR-1339 (n = 5), to further demonstrate the applicability of the technique. Our results suggest that CW-DOS holds promise as a noninvasive and longitudinal tool for monitoring TG concentration, facilitating the diagnosis of HTG and the assessment of the efficacy of interventions aimed at reducing TG levels in individuals.