Preparation of Bridged Thiourea-Based Bis-Tetraphenylethylene Organic Fluorescent Sensor and Application in Detection of Lutein in Water Media
A bridged thiourea-based bis-tetraphenylethylene(Bis-S)organic fluorescent sensor was designed and synthesized with 4-hydroxytetrastyrene and ethyl bromoacetate as starting materials.Bis-S was dissolved in the 95%(volume fraction)tetrahydrofuran solution,and Bis-S solution was prepared.Fluorescence spectrometer was used to measure the fluorescence intensity of the Bis-S system before and after the addition of lutein at excitation wavelength of 360 nm and emission wavelength of 468 nm.It was shown that lutein was added to Bis-S solution or a sensing test paper containing Bis-S,lutein bound to Bis-S at mole ratio of 1∶1,and the bright blue fluorescence of the Bis-S system was quenched due to the encapsulation of lutein by Bis-S cavities.After adding coexisting biomolecules induding guanine,tryptophan,fructose,cytosine,adenine,thymine,vitamin B1,vitamin B2,starch,sucrose,glucose,caffeine,and proline to Bis-S solution or a sensing test paper containing Bis-S,there was no significant change in the fluorescence intensity of the Bis-S system.The above-mentioned coexisting biomolecules were added into the Bis-S solution containing lutein,and there was little change in the fluorescence intensity of the system compared to the absence of coexisting biomolecules,indicating that the Bis-S sensor had the good selectivity and anti-interference property for lutein,and had certain application prospects in colorimetric detection of lutein.The fluorescence intensity of Bis-S system decreased with the increase of lutein concentration at the Bis-S concentration of 1.00×10-5 mol·L-1,giving the detection range within 2.00×10-5 mol·L-1,and linear quantitative detection range within 0.06 µmol·L-1,with detection limit(2s/k)of 1.21×10-9 mol·L-1.Test for recovery was made at 4 concentration levels,giving recoveries in the range of 94.0%-101%,and RSDs(n=6)of the determined values ranged from 1.5%to 4.1%.
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