(1) Ultrasensitive detection of TNT through capillarity-constructed reversible hot spots based on ZnO–Ag nanorod hybrids[1-3]

An simple and efficient self-approach strategy was used to applied ultrasensitive and self-revive ZnO-Ag hybrids surface-enhanced Raman scattering (SERS) spectroscopy sensors for the highly sensitive and selective detection of explosive TNT. Different with other Ag-based SERS sensor, this ZnO-Ag hybrids SERS sensor could rapidly self-revive SERS-active by simple UV light irradiation and keep stable SERS sense ability within 1 month. During the detection, the Raman-inactive trinitrotoluene (TNT) lighted up the ultrahigh Raman scattering of off-resonated p, p’-dimercaptoazobenzene (DMAB) through the formation of charge-transfer DMAB-TNT-DMAB bridge on the flexible ZnO-Ag nanorods array hybrids. Raman hot spots could spontaneously form in a reversible way by the self-approaching of flexible nanorods driven through the capillary force of solvent evaporation.




Meanwhile, the TNT vapor was also collected under this sensor, repeating the addition of ethanol for 5 cycles with the parallel Raman intensity of 4-ATP. The enhancement effect was repeatedly renewable by the reconstruction of molecular bridges and could selectively detect TNT with a limit of 4 × 10-14M. The stable and ultrasensitivity SERS substrates demonstrated a new route to eliminate the oxidized inactive problem of traditional Ag-based SERS substrates and suggested promising applications of such hybrids as real-time online sensors for explosives detection.

2Ultrasensitive detection of TNT through Ag-Nanoparticles Grafted PAN-Nanohump Array Films with 3D High-Density Hot Spots as Flexible and Reliable SERS Substrates[4]

We report a facile fabrication approach to the large-scale flexible films with one surface side consisting of Ag-nanoparticles (Ag-NPs) decorated polyacrylonitrile (PAN) nanohump (denoted as Ag-NPs@PAN-nanohump) arrays via molding PAN films with ordered nanohump arrays on one side and then sputtering much smaller Ag-NPs onto each of the PAN-nanohumps. The surface-enhanced Raman scattering (SERS) activity of the Ag-NPs@PAN-nanohunp array films can be further improved by curving the flexible PAN film with ordered nanohump arrays in the Ag-sputtering process to

   increase the density of the Ag-NPs on the sidewalls of the PAN-nanohumps. Thus more three-dimensional hot spots areachieved on large-scale. The Ag-NPs@PAN-nanohump array films show high SERS activity with good Raman signal reproducibility for Rhodamine 6G probe molecules. For a trial of practical application, the Ag-NPs@PAN-nanohump array films are employed as SERS substrates for trace detection of trinitrotoluene a lower detection limit down to 10-12 M can be achieved respectively. Therefore, the as-fabricated SERS substrates have promising potential in rapid safety inspection and environmental protection.

[1] Xuan He*  Nanoscale2015,7, 8619-8625.

[2] Xuan He*, Physical Chemistry Chemical Physics, 2014, 16, 14706-14712

[3] Xuan He*, Eur. J. Inorg. Chem. 2014, 3176-3182

[4] Zhongbo LiGuowen Meng* Qin Huang* Xuan HeWentao WangSmall, Accept2015