Monodisperse Thermo-responsive Composite Microgels with Core-shell Structure based on Au@Ag Bimetallic Nanorod as Core: Fabrication and Application in SERS Substrate

X. Dong, L.S. Zha
Donghua University, CN

Keywords: smart composite microgels, core-shell structure, Au@Ag bimetallic nanorods, thermo-responsiveness, surface enhanced Raman spectroscopy

Summary:

In summary, monodisperse Au@Ag bimetallic nanorod is encapsulated by crosslinked poly(N-isopropylacrylamide) (PNIPAM) to produce thermo-responsive composite microgel with well-defined core-shell structure (Au@AgNR@PNIPAM microgel) by seed-precipitation polymerization method using butenoic acid modified Au@AgNRs as seeds. Their core-shell structure and thermo-responsive property were identified using TEM and DLLS respectively. As the temperature is raised from 20 to 50℃, their particle size decreases sharply, particularly within the temperature range of 30 to 40℃. The longitudinal localized surface plasmon resonance wavelength of the composite microgels measured by UV-vis spectroscopy is red-shifted from 677 to 704 nm within the same temperature range, indicating they have notable temperature-tunable plasmonic property. When the composite microgels are used as SERS substrates for detection of 210-5 M 1-naphthol in aqueous solution, their SERS activity can be tuned by temperature due to existence of entrapment effect during their temperature triggered volume phase transition.