Novel Liposome-Based Surface-Enhanced Raman Spectroscopy\n(SERS) Substrate

Abstract

Although\ngreat strides have been made in recent years toward making\nhighly enhancing surface-enhanced Raman spectroscopy (SERS) substrates,\nthe biological compatibility of such substrates remains a crucial\nproblem. To address this issue, liposome-based SERS substrates have\nbeen constructed in which the biological probe molecule is encapsulated\ninside the aqueous liposome compartment, and metallic elements are\nassembled using the liposome as a scaffold. Therefore, the probe molecule\nis not in contact with the metallic surfaces. Herein we report our\ninitial characterization of these novel nanoparticle-on-mirror substrates,\nboth experimentally and theoretically, using finite-difference time-domain\ncalculations. The substrates are shown to be structurally stable to\nlaser irradiation, the liposome compartment does not rise above 45\n°C, and they exhibit an analytical enhancement factor of 8 ×\n10⁶ for crystal violet encapsulated in 38 liposomes sandwiched\nbetween a 40 nm planar gold mirror and 80 nm gold colloid.