本文關鍵詞： 石墨烯量子點 氨基酸 功能化 光學傳感 酶促反應活性 染料降解　出處：《江南大學》2017年博士論文　論文類型：學位論文

【摘要】：作為石墨烯家族的最新成員,準零維的石墨烯量子點克服了石墨烯片層之間因較強分子間作用力而導致的堆積和聚集現象,還因顯著的量子限域效應和邊界效應而展現出優(yōu)異的光致發(fā)光性能。石墨烯量子點同時兼具石墨烯和量子點的優(yōu)異性能,加上發(fā)光明亮而穩(wěn)定、水溶性好和生物毒性低的優(yōu)勢,使其在化學傳感、生物成像、醫(yī)學治療和能源相關領域具有更加誘人的前景。然而現有石墨烯量子點發(fā)光效率低、性能單一和功能性差的缺陷限制了其應用的拓展,因此需要制備新的具有特殊功能的石墨烯量子點來滿足不同的需求并拓展石墨烯量子點的應用領域。為此,本論文開展了氨基酸功能化石墨烯量子點的制備、結構對性能影響及復合材料制備等領域應用研究。以20種氨基酸為功能化試劑制備20種氨基酸功能化石墨烯量子點,合成機理研究發(fā)現氨基酸的組成和空間結構會顯著影響功能化石墨烯量子點的形成�？臻g位阻較大的氨基酸傾向于分布在石墨烯量子點的邊緣,而簡單的氨基酸則會部分摻雜到石墨烯量子點內部。此外,光學性質研究發(fā)現氨基酸功能化基團中氮元素的引入使石墨烯量子點的熒光量子產率有明顯的提高,通常量子點邊緣氮原子能夠增加石墨烯量子點的電子密度,使熒光發(fā)射紅移,而內部氮原子較強的吸電子性質則會導致熒光發(fā)射的藍移。石墨烯量子點的表面基團組成和結構顯著影響其光致發(fā)光性能。纈氨酸功能化石墨烯量子點實現了更靈敏和快速的重金屬汞離子熒光檢測,發(fā)現纈氨酸功能基團引入顯著提高了汞離子對量子點的熒光猝滅性能,該方法的靈敏性是未功能化石墨烯量子點的14倍,響應速度提高近10倍。甲硫氨酸功能化石墨烯量子點對環(huán)境中pH值的變化表現出極為靈敏的熒光線性響應,基于此開發(fā)了一種寬范圍的pH熒光傳感器。當體系pH在1~14范圍內,石墨烯量子點的熒光強度隨著pH的增大逐漸增強,在其它緩沖體系中表現出相同的pH熒光響應性。與現有方法相比,新方法在靈敏度、選擇性或響應范圍等主要分析性能上有明顯提高,并成功應用于實際水樣中汞離子和pH值的檢測,在生物細胞RBL-2H3 pH依賴熒光成像中也獲得較好的效果。以H_2O_2氧化降解孔雀石綠染料為模型反應,考察石墨烯量子點結構對染料降解應用中催化性能的影響。結果表明20種氨基酸功能化石墨烯量子點的吸附和催化協同作用均能顯著提高H_2O_2氧化降解孔雀石綠效率。篩選發(fā)現組氨酸功能化石墨烯量子點其富氮咪唑環(huán)提供更多的堿性活性位點,具有最高的催化活性。通過考察影響降解效率的各種因素,得到降解孔雀石綠的最佳條件(50 mg/L孔雀石綠、0.5 mg/mL組氨酸功能化石墨烯量子點、15 mmol/L H_2O_2、35℃),在此條件下,5 min即可降解93%。此外,該過程不需要使用特殊的光照或其它輔助條件,催化劑重復9次后活性沒有明顯的減少。分別以辣根過氧化物酶(HRP)催化H_2O_2氧化四甲基聯苯胺和假單胞菌脂肪酶(PCL)催化L-薄荷醇與乙酸酐合成L-乙酸薄荷酯為模型反應,考察石墨烯量子點作為修飾劑對酶促反應活性調控性能。結果發(fā)現修飾劑的尺寸、表面基團性質和空間構型對生物酶行為有很大影響。HRP在以氧化石墨為前驅體制備的GO-GQD和半胱氨酸功能化石墨烯量子點(Cys-GQD)為修飾劑時分別表現出酶活性和穩(wěn)定性促進和抑制的相反作用效果。圓二色譜研究結果表明,HRP在親水基團較少的GO-GQD作用下結構有序程度增加,有助于酶活性的發(fā)揮。TMB氧化反應產生的藍色物質能夠顯著猝滅石墨烯量子點的熒光,基于GO-GQD能夠提高HRP活性和四甲基聯苯胺氧化產物對GO-GQD熒光猝滅作用建立了一種檢測H_2O_2的方法。PCL在Cys-GQD修飾劑作用下的活性和穩(wěn)定性優(yōu)于氧化石墨修飾,在最佳條件下,L-薄荷醇的轉化率達97.3%,酶的半衰期為224 h,重復使用10次后活性沒有明顯下降。怎樣將石墨烯量子點與其它材料結合,實現它們的優(yōu)勢互補,已逐漸成為研究的熱點。首先以氨基酸功能化石墨烯量子點為還原劑和穩(wěn)定劑一步制備金/石墨烯量子點納米復合材料并考察功能化基團結構對還原性能的影響,發(fā)現石墨烯量子點功能基團組成顯著影響其還原性,脯氨酸因是20種中唯一含二級胺結構的氨基酸,脯氨酸功能化石墨烯量子點其與金離子較強的親和性使其具有最高的還原能力,復合材料的制備在1min內即可完成。復合材料潔凈的表面以及高共軛程度石墨烯量子點負載使復合材料具有更好的電子傳導能力。以復合材料制備的修飾電極在5.0 mmol/L K4[Fe(CN)6]中的ks值為15.58±0.43 cm/s,電子傳遞速率為裸電極的2.86倍,采用差分脈沖伏安方法檢測對乙酰氨基酚進一步研究修飾電極的電化學特性,得到對乙酰氨基酚的檢測下限為0.02μmol/L。論文最后以雙錐形納米金(BPGN)和石墨烯量子點構建了集表面增強拉曼散射(SERS)和熒光雙光譜于一體的雙模探針。首先采用改進方法以少量十二烷基苯磺酸鈉(SDBS)為添加劑、減半十六烷基三甲基溴化銨(CTAB)用量制備BPGN作為SERS基底材料,兩種表面活性劑間的協同作用有助于得到單分散性好且光學性質穩(wěn)定的BPGN。將BPGN與發(fā)光性和生物相容性更優(yōu)的石墨烯量子點組裝于二氧化硅殼層內外兩層制備雙模探針,如此組裝的優(yōu)勢簡單可控,通過更改兩種類型探針可以顯著提高光譜編碼能力。最后采用夾心免疫光學傳感方式實現微囊藻毒素-CL的SERS和熒光方法雙重檢測。
[Abstract]:As the newest member of the family of graphene, graphene quantum dots of quasi zero dimension between the graphene layers due to strong intermolecular force caused by the accumulation and aggregation phenomenon, but also because of the obvious quantum confinement effect and boundary effect and show excellent optical luminescence properties of graphene quantum dots at the same time. With the excellent properties of graphene and quantum dots, with bright and stable, good water solubility and low toxicity advantages, the chemical sensing, biological imaging, has a more attractive prospect of medical treatment and energy related fields. However, the luminous efficiency of the existing graphene quantum dots is low, and the performance of single function the deficiency of low limit the expansion of its application, so we need gqds preparation with special functions to meet different needs and expand the application field of graphene quantum dots. Therefore, this thesis has carried out the amino Acid functionalized graphene quantum dots preparation, effect of structure on performance and preparation of composite materials and other fields. Research and application of functional reagents preparation of 20 kinds of amino functionalized graphene quantum dots with 20 kinds of amino acids, synthesis mechanism study found that the composition and structure of amino acid can significantly influence the formation of functionalized graphene quantum dots. Sterically hindered amino acids tend to be distributed in the gqds edge, and simple amino acids will be part of the internal doped graphene quantum dots. In addition, the research found that the introduction of optical properties of amino acid nitrogen functional groups in the fluorescence quantum yield of graphene quantum dots have significantly improved generally, quantum dot edge nitrogen atom can increase the electron density of graphene quantum dots, the fluorescence emission redshift, and internal nitrogen atoms strong electron withdrawing properties will result in the blue shift of fluorescence emission The surface groups. The composition and structure of graphene quantum dots had significant influence on the photoluminescence properties. Valine functionalized graphene quantum dots to achieve a more rapid and sensitive fluorescence detection of mercury ion, found that valine introduced functional groups can significantly improve the performance of mercury ions on the fluorescence quenching of quantum dots, the sensitivity of the method is 14 times non functionalized graphene quantum dots, to improve the response speed of nearly 10 times. Methionine functionalized graphene quantum dots on the changes in the environment of pH value exhibit extremely linear fluorescence sensitive response, based on the development of pH fluorescence sensor with a wide range of pH. When the system is in the range of 1~14, fluorescence intensity gqds gradually increased with the increase of pH in the other buffer system showed the same pH fluorescence response. Compared with the existing methods, the new method in sensitivity, selectivity and response range of the Lord To analyze the performance has improved significantly, and successfully applied to the detection of mercury ion and pH in actual sample value, in biological cells RBL-2H3 pH dependent fluorescence imaging but also to obtain better results. The degradation of malachite green dye H_2O_2 oxidation as a model reaction of graphene quantum dot structure influence on the catalytic performance of dye degradation application the results show that the adsorption and catalysis. 20 kinds of amino functionalized graphene quantum dots synergy can significantly improve H_2O_2 oxidative degradation of malachite green. The efficiency of screening of histidine functionalized graphene quantum dots of the nitrogen rich alkaline imidazole ring provide more active sites, with the highest catalytic activity. The factors influencing degradation efficiency the optimal conditions of the degradation of malachite green (50 mg/L malachite green, 0.5 mg/mL histidine functionalized graphene quantum dots, 15 mmol/L H_2O_2,35 C), in this article Under 5 min can degrade 93%. in addition, the process does not require the use of special lighting or other auxiliary conditions, repeated 9 times after the catalyst activity was not significantly reduced. With horseradish peroxidase (HRP) catalytic oxidation of H_2O_2 four methyl benzidine and Pseudomonas lipase (PCL) catalyzed L- menthol and acetic anhydride synthesis of L- menthyl acetate as the model reaction of graphene quantum dots as modification agent to promote activity of the enzyme. The results show that the control performance of modified size, surface group properties and spatial configuration of.HRP has a great influence on the graphite oxide was prepared by GO-GQD and cysteine functionalized graphene quantum dots on the biological behavior of enzyme (Cys-GQD) as modification agent were shown to promote enzyme activity and stability and suppression of the opposite effect. Round two chromatography results showed that HRP in hydrophilic groups with less GO-GQD node The orderly degree of increase, contribute to enzyme activity play blue substance produced.TMB oxidation reaction to graphene quantum dot fluorescence quenching was graphite, GO-GQD can improve the activity of HRP and four methyl benzidine oxidation products of GO-GQD fluorescence quenching.PCL method was established for detecting H_2O_2 activity and stability is better than that of modified graphite oxide modifier under the action of Cys-GQD based on L- under the optimum conditions, conversion of menthol rate reached 97.3%, the half-life of the enzyme was 224 h, after 10 times of repeated use without apparent loss of activity. How to combine it with the graphene quantum dot materials, realize their complementary advantages, has gradually become a hot research topic. Firstly, using amino acid functionalized graphene quantum dots as a step in the preparation of gold / graphene quantum dot nanocomposites and study the functional groups structure influence on the reducing capability of reducing agent and stabilizer, found Gqds functional group composition has significant effect on reducing, because it is only 20 proline containing two amine amino acids, proline functionalized graphene quantum dots and its strong affinity for gold ions has the highest reducing ability, preparation of composite materials can be completed within 1min. The composite the material has better electronic conductivity of composite surface clean and high degree of conjugation of gqds load. With composite material prepared modified electrode in 5 K4[Fe mmol/L (CN) 6] in KS was 15.58 + 0.43 cm/s, electron transfer rate was 2.86 times higher than the bare electrode, the electrochemical properties of acetaminophen further study of phenol modified electrode by differential pulse voltammetry method to detect the detection limit by acetaminophen for 0.02 mol/L. in the end to double cone gold nanoparticles (BPGN) and graphene quantum dots are set up The surface enhanced Raman scattering (SERS) dual-mode probe and fluorescence double spectrum in one of the first. The improved method is used with a small amount of twelve sodium dodecyl benzene sulfonate (SDBS) as additive, half sixteen alkyl three methyl bromide (CTAB) dosage of preparation of BPGN as SERS substrate material, two kinds of surface active agent of the synergetic effect of help get well dispersed and stable optical properties of the BPGN. BPGN and the luminescent properties and biocompatibility of superior graphene quantum dots assembled on the silica shell inside and outside the two preparation of dual-mode probe, so the advantages of simple assembly controlled by changing the two types of probes can significantly improve the spectral encoding ability. Finally realize the dual detection of SERS and the fluorescence method of microcystin -CL by sandwich immune optical sensing.

【學位授予單位】：江南大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：O613.71;TB383.1

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本文編號：1449950