Wide range temperature detection with hybrid nanoparticles traced by surface-enhanced Raman scattering

We report on the fabrication of a class of surface-enhanced Raman scattering (SERS) active thermometers, which consists of 60 nm gold nanoparticles, encoded with Raman-active dyes, and a layer of thermoresponsive poly( N -isopropylacrylamide) (PNIPAM) brush with different chain lengths. These SERS-active nanoparticles can be optimized to maintain spectrally silent when staying as single particles in dispersion. Increasing temperature in a wide range from 25 °C to 55 °C can reversibly induce the interparticle self-aggregation and turn on the SERS fingerprint signals with up to 58-fold of enhancement by taking advantage of the interparticle plasmonic coupling generated in the process of thermo-induced nanoparticles self-aggregation. Moreover, the most significative point is that these SERS probes could maintain their response to temperature and present all fingerprint signals in the presence of a colored complex. However, the UV-vis spectra can distinguish the differences faintly and the solution color shows little change in such complex mixture. This proof-of-concept and Raman technique applied here allow for dynamic SERS platform for onsite temperature detection in a wide temperature range and offer unique advantages over other detection schemes.