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A silica ring-based ratiometric fluorescence nanosensing and imaging platform was established for the quantification of miRNA-21 with carbon dots and nucleic-functionalized gold nanoparticles inside and outside the ring, respectively. In the presence of miRNA-21, on one hand, the fluorescence emission signal of the originally quenched 6-carboxyfluorescein (FAM), which was labeled on the nucleic acid molecules that modified on the gold nanoparticles, was re-emitted. On the other hand, the fluorescence intensity of the carbon dots inside the ring remained essentially unchanged, which served to eliminate background interference. The ring rather than the shell well maintained the fluorescence of the carbon dots. The ratio of the recovered fluorescence intensity of FAM to the fluorescence intensity of the carbon dots was linearly correlated with the logarithm of miRNA-21 concentration. The linear range of the probe for miRNA detection was more than 3 orders of magnitude, and the detection limit was as low as 2.5 aM. The feasibility of the method for clinical application was verified by the quantitative analysis of intracellular miRNA. [ABSTRACT FROM AUTHOR]

In this paper, KIT-6 is used as a template to prepare ordered mesoporous materials WO3 and Au-loaded WO3 (Au–WO3). The pristine WO3 sensor and the Au–WO3 sensor are fabricated for the detection of 19 important gases, such as trimethylamine, formaldehyde and CS2. The results show that the Au–WO3 sensor has better selectivity and higher response to TMA. At a working temperature of 268 °C, the response (Ra/Rg) of the Au–WO3 sensor to 100 ppm of TMA is 41.56 and the response time is 1 s. In addition, the sensor has excellent response/recovery capabilities and stability. These high sensing performances are mainly attributed to the electronic and chemical sensitization of the noble metal Au and the presence of a high specific surface area supported by the mesoporous structure. Therefore, Au-doped mesoporous WO3 should be a promising material for a high performance TMA gas sensor. [ABSTRACT FROM AUTHOR]