Optical Behavior of Nile Red in Organic and Aqueous Media Environments
A simple model is proposed to calculate the dimerization constant of a dye in non-aqueous solvents. Alkan-1ols of the formula H–(CH<sub>2</sub>)<sub>n</sub>–OH are used to study the spectroscopic behavior of Nile Red dye. The number <i>n</i> varied from 1 to 8 to...
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MDPI AG
2023-01-01
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| author | Antonio Minò Giuseppe Cinelli Francesco Lopez Luigi Ambrosone |
| author_facet | Antonio Minò Giuseppe Cinelli Francesco Lopez Luigi Ambrosone |
| author_sort | Antonio Minò |
| collection | DOAJ |
| description | A simple model is proposed to calculate the dimerization constant of a dye in non-aqueous solvents. Alkan-1ols of the formula H–(CH<sub>2</sub>)<sub>n</sub>–OH are used to study the spectroscopic behavior of Nile Red dye. The number <i>n</i> varied from 1 to 8 to modulate the medium hydrophobicity. Generally, Nile red is used to localize lipid droplets within cells. This molecule is non-fluorescent in water and other polar solvents but undergoes fluorescence enhancement and large absorption and emission blue shifts in non-polar environments. The calculated equilibrium constants suggest that the aggregation process is solvent-assisted. The absorption and fluorescence emission spectra reveal a marked red shift, which is studied by breaking the wavelength of the maximum band into two terms, showing the contribution of the solvent and the effect of the dye concentration. Both contributions were investigated as a function of the number <i>n</i>, and it was found that alkan-1ols with large <i>n</i> tend to aggregate and produce a smaller red shift. Conversely, it was also noticed that short-chain alkan-1ols stabilize the excited state of the dye via H-bond and the red shift increases. The hydrophilicity of the medium was found to be modulated by adding pure water, in a controlled way, to the binary systems dye–H–(CH<sub>2</sub>)<sub>n</sub>–OH (<i>n</i> = 1–8). The quantification of solvent hydrophilicity is described with the ratio <i>R</i> = <i>water moles/alcohol moles</i>. From this investigation, we realized that the absorption spectra values are strictly connected with the <i>R</i> parameter. In this context, we realized that fluorescence emission spectra allow us to determine the adjustable parameters. |
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| spelling | doaj.art-3266aa231e8049b9a9386416c0ddd7942023-11-16T14:59:46ZengMDPI AGApplied Sciences2076-34172023-01-0113163810.3390/app13010638Optical Behavior of Nile Red in Organic and Aqueous Media EnvironmentsAntonio Minò0Giuseppe Cinelli1Francesco Lopez2Luigi Ambrosone3Department of Biosciences and Territory (DiBT), University of Molise, Contrada Lappone, 86090 Pesche, ItalyDepartment of Agricultural, Environmental and Food Sciences (DiAAA), University of Molise, via F. De Sanctis, 86100 Campobasso, ItalyDepartment of Agricultural, Environmental and Food Sciences (DiAAA), University of Molise, via F. De Sanctis, 86100 Campobasso, ItalyDepartment of Medicine and Health Sciences “V. Tiberio”, University of Molise, via F. De Sanctis, 86100 Campobasso, ItalyA simple model is proposed to calculate the dimerization constant of a dye in non-aqueous solvents. Alkan-1ols of the formula H–(CH<sub>2</sub>)<sub>n</sub>–OH are used to study the spectroscopic behavior of Nile Red dye. The number <i>n</i> varied from 1 to 8 to modulate the medium hydrophobicity. Generally, Nile red is used to localize lipid droplets within cells. This molecule is non-fluorescent in water and other polar solvents but undergoes fluorescence enhancement and large absorption and emission blue shifts in non-polar environments. The calculated equilibrium constants suggest that the aggregation process is solvent-assisted. The absorption and fluorescence emission spectra reveal a marked red shift, which is studied by breaking the wavelength of the maximum band into two terms, showing the contribution of the solvent and the effect of the dye concentration. Both contributions were investigated as a function of the number <i>n</i>, and it was found that alkan-1ols with large <i>n</i> tend to aggregate and produce a smaller red shift. Conversely, it was also noticed that short-chain alkan-1ols stabilize the excited state of the dye via H-bond and the red shift increases. The hydrophilicity of the medium was found to be modulated by adding pure water, in a controlled way, to the binary systems dye–H–(CH<sub>2</sub>)<sub>n</sub>–OH (<i>n</i> = 1–8). The quantification of solvent hydrophilicity is described with the ratio <i>R</i> = <i>water moles/alcohol moles</i>. From this investigation, we realized that the absorption spectra values are strictly connected with the <i>R</i> parameter. In this context, we realized that fluorescence emission spectra allow us to determine the adjustable parameters.https://www.mdpi.com/2076-3417/13/1/638Nile RedpolarityhydrophobicityUV-Vis absorptionfluorescence emission |
| spellingShingle | Antonio Minò Giuseppe Cinelli Francesco Lopez Luigi Ambrosone Optical Behavior of Nile Red in Organic and Aqueous Media Environments Applied Sciences Nile Red polarity hydrophobicity UV-Vis absorption fluorescence emission |
| title | Optical Behavior of Nile Red in Organic and Aqueous Media Environments |
| title_full | Optical Behavior of Nile Red in Organic and Aqueous Media Environments |
| title_fullStr | Optical Behavior of Nile Red in Organic and Aqueous Media Environments |
| title_full_unstemmed | Optical Behavior of Nile Red in Organic and Aqueous Media Environments |
| title_short | Optical Behavior of Nile Red in Organic and Aqueous Media Environments |
| title_sort | optical behavior of nile red in organic and aqueous media environments |
| topic | Nile Red polarity hydrophobicity UV-Vis absorption fluorescence emission |
| url | https://www.mdpi.com/2076-3417/13/1/638 |
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