Nanoporous Gold Disks Functionalized with Stabilized G-Quadruplex Moieties for Sensing Small Molecules.
We report label-free small molecule sensing on nanoporous gold disks functionalized with stabilized Guanine-quadruplex (G4) moieties using surface-enhanced Raman spectroscopy (SERS). By utilizing the unique G4 topological structure, target molecules can be selectively captured onto nanoporous gold (NPG) disk surfaces via π-π stacking and electrostatic attractions. Together with high-density plasmonic "hot spots" of NPG disks, the captured molecules produce a remarkable SERS signal. Our strategy represents the first example of the detection of foreign molecules conjugated to nondouble helical DNA nanostructures using SERS while providing a new technique for studying the formation and evolution of G4 moieties. The molecular specificity of G4 is known to be controlled by its unit sequence. Without losing generality, we have selected d(GGT)7GG sequence for the sensing of malachite green (MG), a known carcinogen frequently abused illegally in aquaculture. The newly developed technique achieved a lowest detectable concentration at an impressive 50 pM, two orders of magnitude lower than the European Union (EU) regulatory requirement, with high specificity against potential interferents. To demonstrate the translational potential of this technology, we achieved a lowest detectable concentration of 5.0 nM, meeting the EU regulatory requirement, using a portable probe based detection system.
Institute for Quality & Safety and Standards of Agricultural Products Research, Jiangxi Academy of Agricultural Sciences , Nanchang, Jiangxi 330200, P. R. China.
Suyan
S
Qiu
Fusheng
F
Zhao
Oussama
O
Zenasni
Jingting
J
Li
Wei-Chuan
WC
Shih
G-quadruplex moieties; malachite green; nanoporous gold disks; small molecule sensing; surface enhanced Raman scattering