【摘要】：量子點(diǎn)(Quantum dots,QDs)是由II-VI族和III-V族元素組成的一種零維半導(dǎo)體納米晶體,具有不同與常規(guī)熒光染料的優(yōu)異熒光特性,基于量子點(diǎn)的熒光傳感分析一直以來是研究的熱點(diǎn)。開關(guān)型熒光傳感是目標(biāo)分子與熒光猝滅劑之間特殊的分子識(shí)別作用而建立起來的一種分析方法。對(duì)目標(biāo)的檢測(cè)具有高度的選擇性和靈敏度,是高靈敏高選擇熒光傳感器構(gòu)建的主要設(shè)計(jì)策略。量子點(diǎn)表面的功能化基團(tuán)是影響量子點(diǎn)傳感性能的重要因素,半胱胺(Cysteamine,CA)是一種巰基胺類化合物,巰基能與量子點(diǎn)的中心金屬原子配位,氨基賦予量子點(diǎn)較好的水溶性、表面正電性等較多的分子功能。本論文就以半胱胺(CA)作為修飾劑和穩(wěn)定劑,通過水熱法,合成CA功能化的Cd Te量子點(diǎn)(CA-CdTeQDs),基于特殊的發(fā)光性能構(gòu)建了三種開關(guān)型熒光傳感器,并通過實(shí)際樣品的檢測(cè),探討了所構(gòu)建熒光傳感器的實(shí)際應(yīng)用可能性,所獲結(jié)果對(duì)于高靈敏高選擇熒光傳感器的構(gòu)建提供了方法學(xué)的參考和依據(jù)。具體內(nèi)容如:(1)基于CA-CdTeQDs-Au NPs的開關(guān)型熒光傳感器測(cè)定谷胱甘肽(GSH)以半胱胺(CA)作為穩(wěn)定劑和修飾劑,碲粉為Te源,Cd Cl2為Cd源,合成CA-CdTeQDs,以檸檬酸鈉作為穩(wěn)定劑和還原劑合成了帶負(fù)電的納米金(Au NPs)。由于Au NPs的紫外-可見吸收光譜與CA-CdTeQDs的熒光光譜有較大部分的重疊,發(fā)生內(nèi)濾光效應(yīng)使CA-CdTeQDs熒光猝滅。Au NPs與GSH強(qiáng)的配位作用,使Au NPs從量子點(diǎn)周圍得到釋放;且GSH在檢測(cè)條件下的正電性,使負(fù)電的Au NPs團(tuán)聚,Au NPs可見吸收光譜紅移,IFT過程受阻,CA-CdTeQDs熒光恢復(fù)�；谏鲜鲈順�(gòu)建了檢測(cè)谷胱甘肽的分子開關(guān)型熒光傳感器。在最優(yōu)的實(shí)驗(yàn)條件下,CA-CdTeQDs的熒光恢復(fù)程度與GSH濃度在6.7-40×104 nmol/L范圍內(nèi)呈線性關(guān)系,檢測(cè)限為3.3 nmol/L。相對(duì)于報(bào)道的方法,該方法有更高的靈敏度和選擇性,10倍的半胱氨酸和高半胱氨酸不干擾測(cè)定,可應(yīng)用于血清中GSH的檢測(cè),為生物GSH的檢測(cè)提供了高靈敏度高選擇提供了方法學(xué)的參考和依據(jù)。(2)基于CA-CdTeQDs-Cu~(2+)開關(guān)型熒光傳感器測(cè)定高半胱氨酸(Hcy)Cu~(2+)與CA-CdTeQDs發(fā)生相互作用,量子點(diǎn)表面狀態(tài)發(fā)生改變,CA-CdTeQDs熒光猝滅。Hcy與Cu~(2+)有較強(qiáng)的配位作用,與CA-CdTeQDs發(fā)生競(jìng)爭(zhēng)結(jié)合,使得Cu~(2+)與CA-CdTeQDs相互作用解除,熒光恢復(fù)�；谝陨显�,構(gòu)建了檢測(cè)Hcy的熒光傳感體系。在優(yōu)化的實(shí)驗(yàn)條件下,體系的熒光恢復(fù)程度與Hcy的濃度在0.05-10μmol/L范圍內(nèi)呈現(xiàn)線性關(guān)系,檢測(cè)限為10 nmol/L。相比文獻(xiàn)的檢測(cè)方法,該方法具有更好的選擇性和靈敏度,較好地解決了結(jié)構(gòu)類似物和樣品中共存物谷胱甘肽和半胱氨酸的干擾,可用于生物血樣中高半胱氨酸的選擇性檢測(cè)。(3)基于CA-CdTe QDs-PSS-甲基紫精(Mv~(2+))開關(guān)型熒光傳感器測(cè)定L-抗壞血酸(AA)帶正電的CA-CdTeQDs作為電子供體,與帶正電的電子受體甲基紫精(Mv~(2+)),在帶負(fù)電的陰離子聚合物聚苯乙烯磺酸鈉(PSS)的橋梁作用下,發(fā)生分子間的電子轉(zhuǎn)移,CA-CdTeQDs熒光猝滅。AA具有強(qiáng)的還原性,可以將Mv~(2+)還原成非電子受體Mv+,CA-CdTeQDs與Mv+之間的電子轉(zhuǎn)移解除,CACdTeQDs的熒光恢復(fù)�；谝陨显順�(gòu)建了檢測(cè)L-抗壞血酸的開關(guān)型熒光傳感體系。在優(yōu)化的實(shí)驗(yàn)條件下,L-抗壞血酸的濃度為0.8-20μmol/L時(shí)與整個(gè)體系的恢復(fù)程度成正比,檢測(cè)限是50 nmol/L。相比報(bào)道的方法,該體系不僅具有較高的檢測(cè)靈敏度,而且也有較好的選擇性,10倍的GSH,Hcy和半胱氨酸均不干擾測(cè)定,可應(yīng)用于血清和細(xì)胞中AA的檢測(cè)。
[Abstract]:Quantum dots (QDs) are zero-dimensional semiconductor nanocrystals composed of II-VI and III-V elements, which have different fluorescence characteristics from conventional fluorescent dyes. Fluorescence sensing based on QDs has been a hot research topic. Switched fluorescence sensing is a special molecule between target molecule and fluorescent quenching agent. An analytical method based on recognition is developed. Target detection with high selectivity and sensitivity is the main design strategy for the construction of highly sensitive and selective fluorescent sensors. In this paper, cysteamine (CA) was used as modifier and stabilizer to synthesize CA-functionalized Cd Te quantum dots (CA-CdTeQDs) by hydrothermal method. Three kinds of open-ended Cd Te quantum dots (CA-CdTeQDs) were constructed based on their special luminescent properties. The practical application possibility of the fluorescence sensor is discussed by the detection of real samples. The results provide a methodological reference and basis for the construction of high sensitive and high selective fluorescence sensor. Specific contents are as follows: (1) The determination of glutathione (GSH) based on the switched fluorescence sensor CA-CdTeQDs-Au NPs. CA-CdTeQDs were synthesized with cysteamine (CA) as stabilizer and modifier, tellurium powder as Te source and Cd Cl2 as Cd source. Negatively charged gold nanoparticles (Au NPs) were synthesized with sodium citrate as stabilizer and reductant. The strong coordination between Au NPs and GSH results in the release of Au NPs from the surrounding quantum dots; the positive nature of GSH leads to the agglomeration of negatively charged Au NPs, the red shift of Au NPs visible absorption spectrum, the blockage of IFT process and the recovery of CA-CdTeQDs fluorescence. Based on the above principle, a molecular switched fluorescence sensor for detecting glutathione is constructed. Under the optimum experimental conditions, the fluorescence recovery of CA-CdTeQDs was linearly related to the concentration of GSH in the range of 6.7-40 *104 nmol/L, and the detection limit was 3.3 nmol/L. Compared with the reported method, this method has higher sensitivity and selectivity. Ten times of cysteine and homocysteine do not interfere with the determination of GSH in serum and can be applied to the detection of GSH in order to live. The detection of GSH provides a methodological reference and basis for high sensitivity and high selectivity. (2) The determination of homocysteine (Hcy) Cu ~ (2+) interacts with CA-CdTeQDs based on CA-CdTeQDs-Cu ~ (2+) switched fluorescence sensor, the surface state of quantum dots changes, and the fluorescence quenching of CA-CdTeQDs. Based on the above principle, a fluorescence sensing system for detecting Hcy was constructed. Under the optimized experimental conditions, the fluorescence recovery degree of the system showed a linear relationship with the concentration of Hcy in the range of 0.05-10 micromol/L, and the detection limit was 10 nmol/L. The method has better selectivity and sensitivity. It can solve the interference of glutathione and cysteine in structure analogue and sample. It can be used for selective detection of homocysteine in biological blood samples. (3) Determination of L-ascorbic acid (AA) by switched fluorescence sensor based on CA-CdTe QDs-PSS-methyl viologen (Mv~ (2+)) The fluorescence quenching of CA-CdTeQDs occurs when the positively charged CA-CdTeQDs and the positively charged electron acceptor methyl viologen (Mv~ (2+) are bridged by the negatively charged anionic polymer sodium polystyrene sulfonate (PSS). AA has strong reducibility and can reduce Mv~ (2+) to non-electron acceptors Mv+, CA-CdTeQDs. The fluorescence of CACdTeQDs was restored when the electron transfer between S and Mv+ was removed. A switched fluorescence sensor system for the detection of L-ascorbic acid was constructed based on the above principle. Under the optimized experimental conditions, the concentration of L-ascorbic acid was 0.8-20 micromol/L, which was proportional to the recovery degree of the whole system, and the detection limit was 50 nmol/L. It has not only high sensitivity but also good selectivity. Ten times of GSH, Hcy and cysteine do not interfere with the determination of AA in serum and cells.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O657.3;TP212

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