Silver nanoparticles loading pH responsive hybrid microgels: pH tunable plasmonic coupling demonstrated by surface enhanced Raman scattering
writer：劉曉云，張晨，查劉生等
keywords：microgels, plasmonic coupling , pH responsiveness, SERS
source：期刊
specific source：RSC Adv., 2013, 3, 3384–3390
Issue time：2013年
The pH responsive hybrid microgels containing homogeneously distributed silver nanoparticles (Ag NPs)
were created by in situ reduction of Ag+ ions coordinated into the microgels with semi-interpenetrating
polymer network structure composed of linear poly(acrylic acid) and crosslinked
poly(N-isopropylacrylamide). When the pH value of the aqueous medium lowers from 6.0 to 4.0, the
localized surface plasmon resonance (LSPR) band of the entrapped Ag NPs is pronouncedly red-shifted
because of the decreased spatial distances between them as a result of shrinkage of the microgels, leading
to their plasmonic coupling. The pH tunable plasmonic coupling is demonstrated by pH dependence of the
surface enhanced Raman scattering (SERS) signal of 4-mercapto benzoic acid anchored on the Ag NPs
surfaces. Differing from static plasmonic coupling modes from nanostructured assembly or array system of
noble metals, the here reported plasmonic coupling can be dynamically controlled by environmental pH
value. Therefore, the pH responsive hybrid microgels have potential applications in mobile LSPR or SERS
microsensors for probing pH values of living tissues or cells.