Quenching Performance of Surfactant-Containing and Surfactant-Free Fluorophore-Doped Mesoporous Silica Films for Nitroaromatic Compound Detection

Abstract

Various surfactant-templated, mesoporous silica thin films containing a phenyl-substituted pyrene fluorophore were prepared and tested as sensors for the nitroaromatic compound 2,4-dinitrotoluene (DNT). The effects of materials parameters on quenching efficiency were evaluated, including the influence of mesopore architecture (wormlike, cubic, or hexagonal mesopores), the presence or absence of the templating surfactant in the mesopores, and the mode of fluorophore incorporation (doping, impregnating, or grafting). Among films with similar components, films with wormlike mesopore architecture exhibited a better quenching performance than those with 2D-hexagonal or 3D-hexagonal mesopore structure. Surfactant-free, fluorophore-bridged films with wormlike mesopores showed the best quenching performance (43% after 5 s and 88% after 60 s), which compares favorably with state-of-the-art sensors based on fluorescent conjugated polymers. Surfactant-containing, fluorophore-doped films with wormlike mesopores were also effectively quenched by DNT, with 39% quenching after 45 s and 94% of quenching after 405 s. It is notable that the surfactant blocks the diffusion of DNT only slightly while it enhances the binding of DNT to the film, boosting the quenching performance.

Luminescent films for chemo- and biosensing

“…169,170 For example, metalloporphyrins serving as sensing units were incorporated in mesoporous silica films using surfactants as structure-directing agents. 172 The inclusion of the surfactant in the surfactantcontaining TKMPP-doped film with worm-like architecture improved the binding interaction between the fluorophore and DNT, resulting in an enhanced quenching performance towards DNT vapor (39% quenching after 45 s and 94% after 405 s) with a detection limit of 10 nM. Not only the mesostructure of the film, but also the strong affinity between analytes and sensing elements provided a fast response time.…”

“…Similarly, a fluorophore-doped mesoporous silica film was designed using pyrene based fluorophores TKMPP. 172 The inclusion of the surfactant in the surfactantcontaining TKMPP-doped film with worm-like architecture improved the binding interaction between the fluorophore and DNT, resulting in an enhanced quenching performance towards DNT vapor (39% quenching after 45 s and 94% after 405 s) with a detection limit of 10 nM. In addition, the silica framework could protect the fluorophores from their undesirable photobleaching, leading to the long-term storage stability of the nanocomposite films.…”

Fluorescence based explosive detection: from mechanisms to sensory materials

“…49,186 The system has been further developed through 183 194 Stein and co-workers reported a phenyl-substituted pyrene fluorophore doped in various surfactant-templated, mesoporous silica thin films. 190 Films with wormlike mesopore architecture exhibited a better quenching performance than those with 2D-hexagonal or 3D-hexagonal structure. The poorer performance of 2D-hexagonal films was attributed to the long channels that lay parallel to the substrate, slowing down the diffusion of DNT through the film.…”

Nanoconfinement of pyrene in mesostructured silica nanoparticles for trace detection of TNT in the aqueous phase

“…Recently, we and others used pyrene excimer fluorescence for the detection of nitroaromatic molecules utilizing nanomaterials that contain chemically attached or more simply physically encapsulated pyrene molecules. 14,[24][25][26][27][28][29][30][31][32] However, most of these studies aimed to detect nitroaromatic explosives in the vapour phase or in organic solvents and studies for the determination of nitroaromatic explosive contaminated water are very rare. [26][27][28][29] In addition, for the materials with pyrene excimer emission, the detection limit in the aqueous phase is generally poor (at the µM level).…”