Plasmonic tweezers have become an important tool for the capture, manipulation, and characterization of nanoparticles (NPs), biomolecules, and viruses. However, the physical environment in the microscale strongly affects the trapping performance of plasmonic nanostructures. We demonstrated the trapping of gamma-aminobutyric acid (GABA) functionalized gold NPs at different solution temperatures and viscosities. Experimental results show that the trapping stiffness decreases from 0.3 to 0.1 fN/nm as the temperature increases from 25°C to 37°C. For solutions with higher viscosity, the trapping stiffness increases but the trapping efficiency would be reduced due to hindered movement of particles.