石墨烯量子点荧光探针测定肾上腺色腙

通过高温裂解柠檬酸合成了水溶性石墨烯量子点(GQDs),并应用钝化剂PEG2000进行修饰,提高了GQDs的量子产率。应用荧光光谱、紫外-可见光谱、红外光谱对其发光特性进行了研究,测定了荧光寿命。实验发现,在p H=7.40的Tris-HCl缓冲液中,肾上腺色腙(CBZC)对GQDs荧光强度有明显的猝灭作用。基于此提出了以GQDs为探针测定肾上腺色腙的新方法。实验考察了缓冲溶液用量、缓冲溶液种类、量子点浓度、反应时间以及表面活性剂等多种因素对反应体系的影响。当量子点浓度为2.3×10-3mol/L时,肾上腺色腙浓度在4.0×10-7~1.2×10-5mol/L(0.995 6)范围内与荧光猝灭值ΔF呈良好的线性关系,方法检出限为1.5×10-7mol/L,相对标准偏差为0.15%(n=5,c=4.0×10-6mol/L)。该方法对于样品中肾上腺色腙含量测定的回收率为97.46%~101.6%。通过测定温度对猝灭常数的影响以及紫外-可见吸收光谱的变化确定了二者的猝灭过程和相互作用力类型。     

苯并噻唑类探针取代基结构对金属离子识别性能的影响

荧光探针对识别金属离子具有检测快、选择性好等特点,设计合成了两个苯并噻唑类探针分子6-(3,5-二甲基苯氧基)-5-胺基-2-苯基苯并噻唑(L4)和6-(3,5-二甲基苯氧基)-5-苯甲酰胺基-2-苯基苯并噻唑(L5),并通过探针分子的紫外可见光谱和荧光光谱的变化特征,详细研究了探针L4和L5对溶液中三价金属离子Al~(3+), Fe~(3+), Cr~(3+)和二价金属离子Cu~(2+)的识别性能。研究结果表明,当L4分子中的识别基团胺基与苯甲酰基键合形成L5分子结构时,会发生荧光猝灭,同时获得了开启式荧光探针L4和关闭式荧光探针L5。紫外可见光谱检测结果表明,在有机溶液中,探针L4选择性地识别出Al~(3+), Fe~(3+), Cu~(2+);在含水乙腈溶液中,探针L4高选择性地识别出Cu~(2+);通过紫外光照射下的裸眼检测,含探针L4的试纸有效地识别出纯水中的Cu~(2+);在有机溶液中,探针L5选择性地识别出Al~(3+)和Fe~(3+)。荧光光谱检测结果表明,当探针L4与Fe~(3+), Al~(3+), Cu~(2+)存在于有机溶液中时, L4将发生荧光猝灭;在含水乙腈溶液中,探针L4对Cu~(2+)具有高选择性识别作用;当探针L5与Cr~(3+), Fe~(3+), Al~(3+), Cu~(2+)存在于有机溶液中时, L5的荧光强度依次增强。利用溶液浓度对吸收强度作图,计算出了探针L4对Cu~(2+)的检出限为4.51×10~(-6) mol·L~(-1),络合常数Kα为1.12×10~3 M~(-1);探针L5对Al~(3+), Cr~(3+), Fe~(3+), Cu~(2+)的检测限分别为2.85×10~(-6), 4.79×10~(-6), 5.95×10~(-6)和3.23×10~(-6) mol·L~(-1),络合常数分别为:Kα(Al~(3+))=2.17×10~3 M~(-1),Kα(Cr~(3+))=2.06×10~3 M~(-1),Kα(Fe~(3+))=3.92×10~3 M~(-1),Kα(Cu~(2+))=4.43×10~3 M~(-1)。根据探针与识别金属离子的荧光滴定实验结果,推测出探针分子与金属离子之间形成了1∶1络合物。抗金属离子干扰实验结果表明,探针分子对特定金属离子的识别基本不受其他干扰金属离子的影响。~1H NMR滴定结果表明,探针L4分子结构中胺基和二甲基苯氧基,探针L5分子结构中的苯甲酰胺基和二甲基苯氧基取代基在识别金属离子过程中发挥了重要作用。探针L4在识别Cu~(2+)方面具有更广阔的应用前景。     

Cu~(2+)参与的N-乙酰基-L-半胱氨酸修饰的CdTe量子点用于测定D-/L-青霉胺

以N-乙酰基-L-半胱氨酸作为修饰剂,合成了高荧光产率的CdTe量子点。在pH为7.80的磷酸缓冲溶液中,Cu~(2+)可以显著猝灭量子点的荧光,有趣的是,在猝灭体系中加入手性青霉胺(PA)可使其荧光恢复。因此基于量子点的荧光变化,建立了快速检测D/L-青霉胺的方法。在最优的实验条件下,NALC-CdTe QDs-Cu~(2+)体系测定青霉胺的范围为2.0×10~(-7)～4.0×10~(-6) mol·L~(-1),检出限为5.8×10~(-8) mol·L~(-1).将该法成功用于实际样品中检测D/L-青霉胺,取得了满意的结果。     

吡罗红为底物的辣根过氧化物酶催化荧光反应测定葡萄糖

吡罗红在辣根过氧化物酶催化下可被过氧化氢氧化而使其荧光猝灭。在pH 7.2中性介质中,稳态催化速率由酶和底物浓度决定,催化体系服从Michaelis-Menten方程,用Lineweaver-Burk作图法求得米氏常数、最大反应速度、催化常数分别为2.4×10~(-5)mol·L-1,2.5×10~(-6)mol·L-1s-1,75.8 s-1。在最佳反应条件下,荧光F0/F的猝灭程度与过氧化氢浓度在0-3.6×10~(-7)mol·L-1范围内成线性关系,检测限为6.3×10~(-9)mol·L-1;当与葡萄糖氧化酶联用时,可定量检测葡萄糖,线性关系为0-8.0×10~(-7)mol·L-1,检测限为3.4×10~(-8)mol·L-1。方法用于分析人血清中葡萄糖含量,分析结果与苯酚-4-氨基安替比林法基本一致。     

酶催化荧光光谱法测定盐酸多巴胺

利用盐酸多巴胺对血红蛋白酶催化荧光体系的猝灭作用,建立了酶催化荧光光谱法测定盐酸多巴胺的新方法.研究了该猝灭体系的最佳实验条件及动力学行为,测定的线性范围为2.1×10-8--8.4×10-4mol/L,检出限为8.2×10-9mol/L.对浓度为5.2×10-6mol/L的盐酸多巴胺进行11次平行测定,其相对标准偏差...     

化学腐蚀法制备荧光多孔硅及对Ag~+的检测

采用简便的化学腐蚀法在45℃下制备了橘红色荧光多孔硅(PS),通过扫描电镜(SEM)、红外光谱(FT-IR)和比表面积(BET)对PS的结构进行了表征。研究发现,Ag~+能在PS上发生氧化沉积而猝灭荧光。基于此,建立了一种快速、灵敏检测Ag~+的新方法。在优化实验条件下,Ag~+浓度与PS的荧光强度在4.5×10~(-8)~6.6×10~(-7)mol/L范围内呈良好的线性关系,检测限为2.2×10~(-8)mol/L,线性相关系数为0.991 4。该方法用于水样中Ag~的检测,结果满意。     

DMF保护的荧光银纳米簇的制备及其对Hg~(2+)浓度的检测

采用N,N-二甲基甲酰胺(DMF)作为还原剂和保护剂,在140℃下回流反应,简便合成了荧光银纳米簇(DMF-Ag NCs)。通过高分辨率透射电镜(HRTEM)、紫外-吸收光谱、荧光光谱对DMF-Ag NCs进行了表征。研究发现,Hg~(2+)会使DMF-Ag NCs聚集而猝灭荧光。基于此,建立了一种快速、灵敏检测Hg~(2+)的新方法。在最佳实验条件下,Hg~(2+)溶液浓度与DMF-Ag NCs荧光强度在5.0×10-9~1.5×10-7mol/L范围内呈良好的线性关系,检测限为3.0×10-9mol/L,线性相关系数为0.995 8。该方法可用于环境水样中Hg~(2+)的检测。     

光谱法研究吖啶橙与明胶蛋白质的相互作用

在pH=7.0及不同温度下,利用荧光法、同步荧光法和紫外-可见吸收光谱研究了吖啶橙和明胶蛋白质的相互作用。荧光猝灭可分为静态猝灭和动态猝灭两种方式。通过实验可知吖啶橙与明胶属于静态荧光猝灭;得不同温度下的反应猝灭常数KSV(288 K:7.831×103L/mol;303 K:6.908×103L/mol;318 K:5.777×103L/mol),且用同步荧光技术考察了吖啶橙对明胶蛋白质构象的影响。     

基于CdTe量子点荧光猝灭-恢复方法测定依诺沙星的研究

水相合成了巯基丙酸保护的CdTe量子点。根据在Cu2+存在的情况下,CdTe量子点荧光恢复程度与依诺沙星浓度成正比的现象,建立了基于CdTe量子点荧光猝灭-恢复测定依诺沙星的新方法。考察了溶液pH值以及Cu2+浓度等对检测体系的影响。在p H=10的硼砂缓冲溶液中,在Cu2+浓度为2.3×10-5mol/L的条件下,依诺沙星浓度在8.0×10-7~3.0×10-5mol/L范围内与量子点荧光恢复程度呈良好的线性关系,检出限为7.2×10-8mol/L。该方法用于实际样品中依诺沙星的检测,回收率为95.5%~105.0%。     

量子点CdSe/CdS-微囊藻毒素-LR抗体生物共轭体测定环境水样中的微囊藻毒素-LR

建立了一种基于CdSe/CdS量子点(QDs)标记技术测定微囊藻毒素-LR(MC-LR)的方法。MC-LR抗体经1-乙基-3(3-二甲基胺基丙基)碳二亚胺盐酸盐(EDC)活化,与经巯基乙酸修饰的CdSe/CdS量子点进行共价连接,获得的QDs生物共轭体在待测物MC-LR的作用下发生荧光猝灭现象,荧光猝灭程度与MC-LR的浓度呈线性关系。该方法操作简单、检测速度快、检出限低达6.9×10~(-11)mol/L。     

氨基化碳量子点荧光猝灭法测定焦性没食子酸的研究

以葡萄糖为原料,通过一步水热法合成稳定性高的碳量子点,并用乙二胺使其表面氨基化。焦性没食子酸能使氨基化的碳量子点荧光明显猝灭,由此建立一种简便、高效检测焦性没食子酸的新方法。考察了缓冲体系p H、反应时间、反应温度等对焦性没食子酸测定的影响。结果表明,在pH=11.20的三酸缓冲溶液中,室温反应20 min时,体系的F0/F与焦性没食子酸的浓度呈良好的线性关系,其线性范围为4.0×10~(-6)~9.0×10~(-5)mol·L~(-1),相关系数r=0.997 4,检出限为3.5×10~(-6)mol·L~(-1)。该方法快速简便,适用于水样中焦性没食子酸的检测。     

Hydrothermal synthesis of functionalized CdS nanoparticles and their application as fluorescence probes in the determination of uracil and thymine

A novel, sensitive, and convenient method for the determination of uracil and thymine by functionalized CdS nanoparticles (NPs) was proposed. CdS NPs were prepared by hydrothermal process and modified with thioglycollic acid (TGA) in aqueous solution. The fluorescence intensity of functionalized CdS NPs was quenched in the presence of uracil or thymine. Under optimal conditions, the relative fluorescence intensity (F₀/F) was proportional to the concentration in the range of 9.0×10^?6–1.0×10^?4 mol/L for uracil (r=0.9985) and 8.8×10^?7–1.5×10^?4 mol/L for thymine (r=0.9960). The corresponding detection limits were 9.6×10^?7 mol/L and 3.2×10^?7 mol/L, respectively. In addition, the possible quenching mechanism was also discussed.     

Spectrofluorometric Determination of Iron II Based on the Fluorescence Quenching of Cadmium/Tellurium Quantum Dots

Water-soluble and stable CdTe quantum dots were synthesized in aqueous solution with thioglycolic acid as the stabilizer. A spectrofluorometric method for the determination of iron (II) has been developed based on quenching of the fluorescence of CdTe quantum dots by iron (II) in aqueous solutions. It can perform an accurate and simple determination of iron (II) concentration in water samples. Under optimum conditions, the quenched fluorescence intensity increased linearly with the concentration of iron (II) ranging from 5.0 × 10^?8 to 4.0 × 10^?6 mol/L with a correlation coefficient R = 0.9969. The limit of detection for iron (II) was found to be 1.2 × 10^?8 mol/L. As an application, the proposed method was successfully applied to the analysis of iron (II) in water samples, and the results were satisfactory.     

巯基乙胺稳定的CdTe量子点荧光猝灭法测定间苯二酚

以CdTe量子点作为荧光探针,基于荧光猝灭法对间苯二酚进行了定量检测,考察了缓冲溶液体系、量子点浓度、反应时间等多种因素的影响.实验结果表明,在pH 6.5的0.2mol/LNa<,2>HPO<,2>-NaH<,2>PO<,4>缓冲液中,反应时间为15min.间苯二酚浓度为1.6×10<'-6>-2.0×10<'-5>...     

A New Spectrofluorimetric Method for Determination of Trace Amounts 5-Hydroxytryptamine in Human Urine and Serum

A new spectrofluorimetric method was developed for the determination of trace amount of 5-hydroxytryptamine (5-HT) in human urine and serum samples. In the NaAc-HAc buffer solution of pH=5.80, 5-HT can react with formaldehyde-acetylacetone system to form a new compound which sends yellow green fluorescence at 533nm and the enhanced fluorescence intensity is in proportion to the concentration of 5-HT. Optimum conditions for the determination of 5-HT were also investigated. The dynamic range and detection limit for the determination of 5-HT are 5.35×10⁻⁷∼1.07×10⁻⁴ mol/L and 2.08×10⁻⁷ mol/L, respectively. The developed method is simple, practical and can be successfully applied to determination of 5-HT in human urine and serum samples. Moreover, the enhancement mechanisms of the fluorescence intensity in the 5-HT - formaldehyde-acetylacetone system have been also discussed.     

Determination of Paracetamol Based on its Quenching Effect on the Photoluminescence of CdTe Fluorescence Probes

L-Cysteine capped CdTe nanoparticles (NPs) were synthesized in aqueous medium, and their application as fluorescence probes in the determination of paracetamol was studied. The L-cysteine capped CdTe NPs were characterized by transmission electron microscopy, X-ray diffraction spectrometry, spectrofluorometry, ultraviolet-visible and Fourier transform infrared spectrometry. Based on the distinct fluorescence quenching of CdTe fluorescence probes in the presence of paracetamol, a simple, rapid and specific method for paracetamol determination was presented. Under optimum conditions, the relative fluorescence intensity of CdTe NPs was linearly proportional to paracetamol concentration from 1.0 × 10⁻⁸ mol/L to 1.6 × 10⁻⁷ mol/L with a detection limit of 4.2 × 10⁻⁹ mol/L. The proposed method was applied to detect paracetamol in commercial tablets with satisfactory results.     

CdTe量子点荧光猝灭法测定钴

以CdTe量子点作为荧光探针,基于荧光猝灭法对钴(Ⅱ)进行了定量检测,考察了缓冲溶液体系、量子点浓度、反应时间等多种因素的影响。实验结果表明,在pH8.0的0.2mol/LNa2HPO4-NaH2PO4缓冲液中,反应时间为10min,钴(Ⅱ)浓度为1.6×10-5—20×10-5mol/L范围时,其线性回归方程为F0/F=1.45+0.096Q(10-5mol/L),检出限为3×10-7mol/L。该方法检测范围宽,灵敏度高,为钴的测定提供了新的方法。     

Graphene Quantum Dots from Polycyclic Aromatic Hydrocarbon for Bioimaging and Sensing of Fe3+ and Hydrogen Peroxide

An easy approach for large‐scale and low‐cost synthesis of photoluminescent (PL) graphene quantum dots (GQDs) based on the carbonization of commercially available polycyclic aromatic hydrocarbon (PAH) precursors with strong acid and followed by hydrothermal reduction with hydrazine hydrate is reported. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) characterizations indicate that the size and height of GQDs are in the range of 5–10 nm and 0.5–2.5 nm, respectively. PAH, which has more benzene rings, generally forms GQDs with relatively larger size. The GQDs show high water solubility, tunable photoluminescence, low cytotoxicity, and good optical stability, which makes them promising fluorescent probes for cellular imaging. In addition, the fluorescence of GQDs shows a sensitive and selective quenching effect to Fe³⁺ with a detection limit of 5 × 10^?9m . By combination with the Fe²⁺/Fe³⁺ redox couple, the PL GQDs are able to detect oxidant, using H₂O₂ as an example. This study opens up new opportunities to make full use of GQDs because of their facile availability, cost‐effective productivity, and robust functionality.