The Fluorescent Nanoprobe Based On β-cyclodextrin And Its Application In Cosmetic Analysis

With the improvement of people’s consumption level,the use of cosmetics in daily life is substantially increased.However,many cosmetics have been detected to contain toxic substances that are harmful to human health.The conventional analytical methods,such as liquid chromatography,gas chromatography and chromatography-mass spectrometry usually require complicated sample pretreatment and prolonged analysis time,which make these methods not suitable for quick screening of prohibited substances in cosmetic products.Fluorescence spectrometry has the advantages of simple procedure,low cost,and fast analysis,hence has been widely used in many fields such as chemical sensing,biological imaging and medicine screening.Theβ-Cyclodextrins（β-CD）has hydrophobic cavities and hydrophilic outer surfaces,which is widely used in the fields of drug delivery,separation,identification,and selective detection.By usingβ-cyclodextrin as the raw material,we have developed different nano fluorescent probes,intend to achieve sensitive,efficient,and selective detection of targeted substances in complex cosmetics samples.The main research contents are as follows:（1）Gold nanoparticles coated withβ-cyclodextrin（β-CD@AuNPs）were prepared fromβ-cyclodextrin and chlorauric acid.The structure and optical properties ofβ-CD@Au NPs were investigated by a series of characterization.Based on the fluorescence quenching of Rhodamine B（Rh B）byβ-CD@Au NPs and the fluorescence recovery ofβ-CD@Au NPs-RB system by sex hormones（progesterone,estradiol and testosterone）,a highly selective and sensitiveβ-CD@Au NPs-RB fluorescence probe was constructed to detect the content of sex hormones.The results showed that the fluorescence intensity increased with the increase of sex hormone concentration in the range of 0～7.5μg/g（progesterone）and 0～15μg/g（estradiol and testosterone）,and the fluorescence recovery rate showed a good linear relationship with the concentration.The detection limits of this method were 0.047μg/g（progesterone）,0.15μg/g（estradiol）and 0.37μg/g（testosterone）,respectively.In addition,theβ-CD@Au NPs-RhB probe was used for the detection of three sex hormones in toner samples.The results are in good agreement with the actual additive content,indicating that the probe has a good application prospect.（2）In the second part of thesis,one kind of excited independent blue fluorescent carbon dots（B-CDs）was prepared by one-step hydrothermal method from singleβ-CD.The structure and optical properties of B-CDs were investigated by a series of characterization.According to the quenching effect of tetracycline hydrochloride（TC）on the fluorescence of B-CDs,and the different fluorescence of TC itself under different p H conditions（red at acid,green at alkaline）,a p H-mediated double-channel ratio fluorescence probe based on B-CDs was successfully constructed for the detection of TC.Experimental results showed that the probe could detect TC in the range of 0～50μg/g under acidic conditions and 0～20μg/g under alkaline conditions.Detection limits were 103 ng/g and 18 ng/g,respectively.The development of the probe provided the possibility for the efficient and sensitive detection of TC.In addition,this strategy of using derived reactions of the target itself can be extended to the development of fluorescent probes for other detection substances.（3）Copper nanoclusters（β-CD@CuNCs）with good optical stability were synthesized usingβ-cyclodextrin as the coating agent and combined with B-CDs synthesized in the previous chapter,β-CD@Cu NCs-B-CDs fluorescence probe with dual emission function was constructed,with good fluorescence properties at 435 nm and 650 nm.The composite system had cheap raw materials and simple synthesis process.When Cr（Ⅵ）was present,β-CD@Cu NCs would interact with Cr（Ⅵ）,causing fluorescence intensity quenching at 650 nmβ-CD@Cu NCs,while the fluorescence intensity of B-CDs at 435 nm was not affected.Under the optimal conditions,the emission intensity ratio ofβ-CD@Cu NCs-B-CDs probe(F₄₃₅/F₆₅₀)had a good linear relationship with the concentration of Cr（Ⅵ）in the range of 0.2～1μg/g and2～6μg/g,and the detection limit was 5.6 ng/g.In addition,β-CD@Cu NCs-B-CDs composite system can realize the rapid and sensitive detection of Cr（Ⅵ）in cosmetics,providing a new idea for the detection of banned substances in cosmetics.