Preparation of SERS active Ag nanoparticles encapsulated by phospholipids

Abstract

A cost-effective way of fabricating lipid-coated surface-enhanced Raman spectroscopy (SERS) substrate having reproducible high SERS activity was proposed. Ag nanoparticle embedded in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) membranes was produced by direct deposition of a 5-nm-thick layer of Ag onto the solid-supported phospholipid membrane, and subsequent dissolution of the Ag nanoparticle-embedded membrane in iso-octane allowed easy one-pot fabrication of DOPC- or DOTAP-coated Ag nanoparticles. In particular, DOTAP produced nearly monodisperse lipid-encapsulated Ag nanoparticles (9nm in diameter) exhibiting reproducible high SERS activity (detecting up to 10nM of rhodamine 6G and 0.5M of glutathione). In addition, the process was modified to incorporate variety of Raman active molecules (rhodamine 6G, malachite green, 4-aminothiopheonol, 4-mercaptopyridine) into the particle-encapsulating lipid bilayer. The DOTAP/Raman dye-coated Ag nanoparticles also generated high SERS activity to enable potential application of the DOTAP/Raman dye-coated Ag nanoparticles feasible in different areas. Copyright (C) 2014 John Wiley & Sons, Ltd.