The monodisperse thermo-responsive composite microgels with well-defined core–shell structure based
on gold nanorod as core and crosslinked poly(N-isopropylacrylamide) as shell were fabricated by seedprecipitation
polymerization method using butenoic acid modified AuNRs as seeds. Their core–shell
structure and thermo-responsive property were verified by electron transmission microscopy, atomic
force microscopy and dynamic light scattering technique, respectively. The ultraviolet–visible-near
infrared absorption spectra measured at various temperatures show that the longitudinal localized surface
plasmon resonance (LSPR) wavelength of the AuNR embodied inside the microgel can be reversibly
tuned from 750 to 800 nm as temperature is changed within the range from 30 to 40 ?C, indicating that
the plasmonic property of the composite microgel is temperature-tunable. When the composite microgels
are used as surface enhanced Raman scattering (SERS) substrates for detection of the analyte having
low affinity toward metal surface, their SERS activity can be modulated by temperature due to existence
of the entrapment effect during their temperature triggered volume phase transition.
