Researchers at Jackson State University successfully used SERS to detect the human immunodeficiency virus (HIV). To begin the study, they first tested gold nanoparticles of varying shapes to determine which would show the greatest electromagnetic enhancement.
Spherical, cage, and popcorn-shaped gold nanoparticles were tested using Rhodamine 6G dye, a well-known Raman-active compound. The system used to make the measurements comprised an Ocean Insight QE series spectrometer, a 670 nm excitation laser and InPhotonics fiber optic Raman probe (Figure 1). The popcorn-shaped nanoparticles resulted in >50x more electromagnetic enhancement of the Raman signal than other conformations, most likely due to the sharp tips on the nanoparticle creating a “lightning rod effect” in addition to the known surface plasmon excitations.
Figure 1: Modular fiber optic Raman spectroscopy system for SERS detection.