The preparation of surface-enhanced fluorescence(SEF) substrates is often influenced by experimental strategies and factors such as the morphology and size of the nanostructures. In this study, using the natural reed ...The preparation of surface-enhanced fluorescence(SEF) substrates is often influenced by experimental strategies and factors such as the morphology and size of the nanostructures. In this study, using the natural reed leaves(RLs) without any special pretreatment as the substrate, metal silver is modified by magnetron sputtering technology to prepare a stable and efficient SEF system. The abundant “hedgehog-like” protrusions on the RL substrate surface can generate high-density“hot spots”, thus enhancement factor(EF) is enhanced up to 3345 times. The stability and reproducibility are verified in many measurements. The contribution of the intervention of silver nanostructure to the radiation attenuation process of fluorescent molecules is analyzed with the aid of Jablonski diagrams. Three-dimensional(3D) finite difference time domain(FDTD) simulates the spatial electric field and “hot spots” distribution of the substrate. The “hedgehog-like” protrusion structure generates multiple “hot spots”, which produce an excellent local surface plasmon resonance(LSPR) effect and provide higher fluorescence signal. Finally, RL/Ag-35 substrate is used to detect crystal violet(CV), and the detection limit is as low as 10^(-13) M. This “hedgehog-like” SEF substrate provides a new strategy for the trace detection of CV, which has a good practical application value.展开更多
Introduction:Highmercury(Hg)concentrations affect the chlorophyll in leaves,therebymodifying leaf spectra.Hyperspectra is a promising technique for the rapid,nondestructive evaluation of leaf Hg content.In this study,...Introduction:Highmercury(Hg)concentrations affect the chlorophyll in leaves,therebymodifying leaf spectra.Hyperspectra is a promising technique for the rapid,nondestructive evaluation of leaf Hg content.In this study,we investigated Hg contents and reflective hyperspectra of reed leaves(Phragmites communis)in a gold mining(Jilin province,China).Spectral parameters sensitive to Hg content were identified through basic spectral transformations,continuous wavelet transformation(CWT),and spectral indices techniques.Leaf Hg inversion models were developed using stepwise multiple linear regression,partial least squares regression,and random forest algorithms.Outcomes:The results indicated that:1)leaf Hg content decreased with increasing distance from the mine:Jiapigou(JPG)>Erdaocha(EDC)>Laojingchang(LJC)>Erdaogou(EDG)>Lingqian(LQ)>Weishahe(WSH).2)Hg–sensitive wavelengths were primarily in the visible region;CWT increased the correlation between hyperspectral data and leaf Hg content,and improved the regression and accuracy of inversion;3)the continuumremoval–CWT–stepwise multiple linear regression was better for estimating low leaf Hg content;while the differential spectral index–partial least squares regression was better for estimating high leaf Hg content.Conclusion:These hyperspectral inversion methods could be used for rapid,nondestructive monitoring of wetland plants.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11674275, 21872119, 22072127, and 12104392)the Science and Technology Project of Hebei Education Department, China (Grant No. ZD2019069 and QN2021142))。
文摘The preparation of surface-enhanced fluorescence(SEF) substrates is often influenced by experimental strategies and factors such as the morphology and size of the nanostructures. In this study, using the natural reed leaves(RLs) without any special pretreatment as the substrate, metal silver is modified by magnetron sputtering technology to prepare a stable and efficient SEF system. The abundant “hedgehog-like” protrusions on the RL substrate surface can generate high-density“hot spots”, thus enhancement factor(EF) is enhanced up to 3345 times. The stability and reproducibility are verified in many measurements. The contribution of the intervention of silver nanostructure to the radiation attenuation process of fluorescent molecules is analyzed with the aid of Jablonski diagrams. Three-dimensional(3D) finite difference time domain(FDTD) simulates the spatial electric field and “hot spots” distribution of the substrate. The “hedgehog-like” protrusion structure generates multiple “hot spots”, which produce an excellent local surface plasmon resonance(LSPR) effect and provide higher fluorescence signal. Finally, RL/Ag-35 substrate is used to detect crystal violet(CV), and the detection limit is as low as 10^(-13) M. This “hedgehog-like” SEF substrate provides a new strategy for the trace detection of CV, which has a good practical application value.
基金This work was supported by the Fundamental Research Funds of Central-level Nonprofit Research Institutes of China[CAFINT2014K05].
文摘Introduction:Highmercury(Hg)concentrations affect the chlorophyll in leaves,therebymodifying leaf spectra.Hyperspectra is a promising technique for the rapid,nondestructive evaluation of leaf Hg content.In this study,we investigated Hg contents and reflective hyperspectra of reed leaves(Phragmites communis)in a gold mining(Jilin province,China).Spectral parameters sensitive to Hg content were identified through basic spectral transformations,continuous wavelet transformation(CWT),and spectral indices techniques.Leaf Hg inversion models were developed using stepwise multiple linear regression,partial least squares regression,and random forest algorithms.Outcomes:The results indicated that:1)leaf Hg content decreased with increasing distance from the mine:Jiapigou(JPG)>Erdaocha(EDC)>Laojingchang(LJC)>Erdaogou(EDG)>Lingqian(LQ)>Weishahe(WSH).2)Hg–sensitive wavelengths were primarily in the visible region;CWT increased the correlation between hyperspectral data and leaf Hg content,and improved the regression and accuracy of inversion;3)the continuumremoval–CWT–stepwise multiple linear regression was better for estimating low leaf Hg content;while the differential spectral index–partial least squares regression was better for estimating high leaf Hg content.Conclusion:These hyperspectral inversion methods could be used for rapid,nondestructive monitoring of wetland plants.
