Potential of Raman Spectroscopy for Blood-Based Biopsy

Blood is a rich source of potential biomarkers for disease screening, risk assessment, detection, and prognosis. It is comprised of free-floating erythrocytes, leukocytes, platelets, and a nutrient-rich fluid of plasma. Blood samples are readily accessible in a minimally invasive manner compared to solid tissue biopsies; this enables repeated monitoring of the health status of a patient. Components of blood that can alter based on disease include metabolites such as glucose and lactic acid, immune markers such as cytokines and antibodies, and ions such as calcium and phosphate. Changes in levels of these components can be indicative of tumor growth, infection, and/or organ malfunction [1]. It is hardly surprising, therefore, that liquid biopsy based on blood is rapidly emerging as a complementary diagnostic approach to standard imaging and solid tissue biopsy for disease detection [2]. Current blood diagnostic assays, however, typically detect single biomarkers (e.g., pH [3], prostate specific antigen (PSA) in prostate cancer, cancer antigen 125 (CA125) in ovarian cancer). This can be very limiting since the heterogeneous nature of most diseases may require measurements of multiple biomarkers to ensure high specificity of detection.