HKUST-Shenzhen Research Institute 1 article published in JoVE Bioengineering Optical Trapping of Plasmonic Nanoparticles for In Situ Surface-Enhanced Raman Spectroscopy Characterizations Xin Dai1,2, Wenting Qiu1,2, Jinqing Huang1,2 1HKUST-Shenzhen Research Institute, 2Department of Chemistry, The Hong Kong University of Science and Technology The present protocol describes a convenient approach to integrating optical trapping and surface-enhanced Raman spectroscopy (SERS) to manipulate plasmonic nanoparticles for sensitive molecular detection. Without aggregating agents, the trapping laser assembles plasmonic nanoparticles to enhance the SERS signals of target analytes for in situ spectroscopic measurements.