Detection of Saturated Fatty Acids Associated with a Self-Healing Synthetic Biological Membrane Using Fiber-Enhanced Surface Enhanced Raman Scattering

The Synthetic Biological Membrane (SBM) project at NASA Ames developed a portable, self-repairing wastewater purification system. The self-repair process relies upon secreted fatty acids from a genetically engineered organism. However, solubilized fatty acids are difficult to detect using conventional methods. Surface-enhanced Raman scattering (SERS) was used to successfully detect solubilized fatty acids with the following limits of detection: 10–9, 10–8, 10–9, and 10–6 M for decanoic acid, myristic acid, palmitic acid, and stearic acid, respectively. Additionally, hollow core photonic crystal fiber (HCPCF) was applied as the sampling device together with SERS to develop in situ surveillance of the production of fatty acids. Using SERS + HCPCF yielded an 18-fold enhancement in SERS signal for the CH2 twist peak at 1295 cm–1 as compared to SERS alone. The results will help the SBM project to integrate a self-healing wastewater purification membrane into future water recycling systems.