Applications of Surface Enhanced Raman Scattering toward the Detection of the Bioactive Lipid 20-HETE

The detection and analysis of lipids in biological matrices for clinical applications poses many challenges, but rapid and reliable detection will prove invaluable for clinical diagnosis. Herein, we report the application of drop-cast triangular Ag nanoplatelets as surface enhanced Raman scattering (SERS) substrates for qualitative detection of 20-hydroxyeicosatetraenoic acid (20-HETE), which is a potential biomarker for diagnosis of hypertensive disorders. The substrates were modified to increase SERS signal enhancement of 20-HETE, both by itself and in combination with structurally similar lipids that are known to exist in significantly high concentrations in human blood, simulating an ethanol extract of plasma, and analyzed with a Raman system employing a 532 nm laser excitation source. Biomarker peaks of 20-HETE can be reliably detected and differentiated from those of the structurally similar lipids (arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid) commonly found in human blood, even at 1 pM concentrations. Additionally, one study mixed 20-HETE with three structurally similar lipids at concentrations several orders of magnitude greater than the target lipid and 20-HETE could still be detected under these conditions. These experiments demonstrate the viability of SERS for the rapid and reliable detection of endogenous bioactive lipids, which has significant clinical impact in enabling point of care disease diagnostics and treatment monitoring for hypertensive disorders.