水溶性荧光碳量子点的制备及其Cu~(2+)传感性能研究

以腐殖酸为碳源制备水溶性碳量子点,并将其应用于Cu~(2+)的检测,研究其传感性能。结果表明,该水溶性荧光碳量子点的平均粒径在3nm左右,具有优异的光致发光性能,对Cu~(2+)具有较高的选择性;在Cu~(2+)浓度为20μmol·L~(-1)时,碳量子点对其响应时间为12s,且在0~20μmol·L~(-1)浓度范围内,碳量子点荧光强度的对数值与Cu~(2+)浓度具有较好的线性相关性。为水溶性荧光碳量子点检测Cu~(2+)提供了可能。     

以谷胱甘肽修饰的CdTe量子点为荧光探针测量超痕量As(Ⅲ)

以谷胱甘肽(GSH)为稳定剂,在水相中制备了CdTe量子点,基于As3+离子对量子点荧光的淬灭作用,建立了定量测定As3+离子的方法。CdTe量子点对As3+离子呈现出高选择性,其它常见金属离子的存在对铜的测定几乎不产生干扰。考察了不同反应时间和不同价态砷等因素对CdTe量子点的影响,量子点的相对荧光强度与As3+离子的浓度呈很好的线性关系,该方法的线性范围为0.2~2·2μM,检出限为20 nM。本方法简单、快速,与文献报道的其它基于量子点荧光探针As3+离子分析方法相比,此法对As3+离子呈现出更高的选择性。将此法用于实际废水中As3+离子含量的测定,结果令人满意。     

吲哚衍生物改性的碳纳米管铜离子荧光传感器

用吲哚衍生物(INDOLE)共价修饰在碳纳米管的表面获得了一种高效的荧光检测器,并通过红外光谱和热重分析对其表征。研究了常见金属离子Zn~(2+),Cd~(2+),Mg~(2+),Ca~(2+),Ni~(2+)和Cu~(2+)对吲哚衍生物共价修饰的碳纳米管(MWNTs-INDOLE)荧光光谱的影响,通过荧光测试表明MWNTs-INDOLE对铜离子具有荧光选择性,并且随着铜离子浓度的增加荧光强度逐渐减弱,加入1×10~(-5)mol/L的Cu~(2+),MWNTs-INDOLE的荧光被淬灭50%。     

罗丹明B类Cu~(2+)荧光增强型探针的合成及其选择性识别

设计并合成了一种可用于识别的Cu~(2+)新型荧光探针(3',6'-双(二乙氨基)-2-(4-(二乙氨基)-2-羟基苯胺基-螺(异喹啉-1,9'-氧杂蒽)-3-酮)(RB)。通过红外、元素分析、质谱、~1HNMR、~(13)CNMR等手段表征了探针的结构。其光谱性和离子选择性实验结果表明,RB自身荧光很弱,但是与Cu~(2+)结合后会发生显著的荧光增强,而与其他金属离子结合后,荧光强度变化很小。说明RB对Cu~(2+)具有很好的选择性和较高的灵敏度,可用作Cu~(2+)荧光增强型探针,据此建立了一种测定Cu~(2+)的新型分析方法。     

一种新型罗丹明类双通道荧光探针及其对Fe~(3+)和Cu~(2+)的选择性识别研究

以罗丹明B、水合肼和吡啶-2-甲醛为反应物,合成了一种新型的罗丹明类Fe~(3+)和Cu~(2+)双通道分子探针(Fluorescent probe,FP),并用核磁和质谱对其分子结构进行了表征。利用荧光分光光度计和紫外可见分光光度计研究了FP对Fe~(3+)、Cu~(2+)等14种金属离子的识别性能。研究结果表明,在V(CH_3OH)∶V(H_2O)=1∶1体系中,当选用荧光光谱分析时,探针FP对Fe~(3+)具有良好的选择性响应,且Fe~(3+)浓度在2~30μmol/L时,探针荧光强度与Fe~(3+)浓度呈线性关系,线性相关系数为0.998。当选用紫外可见光谱分析时,探针FP对Cu~(2+)具有很好的选择性响应,且当Cu~(2+)浓度为0~9μmol/L时,探针FP的吸光度与Cu~(2+)浓度呈线性关系,线性相关系数为0.999。     

一种Cu~(2+)荧光探针的合成及其性质研究

设计合成了Cu~(2+)种新型的Cu~(2+)荧光探针NPE,并利用元素分析、核磁、质谱等方法对探针结构进行表征。室温下,在乙醇和水的混合溶液中的荧光性质研究发现,探针NPE对于Cu~(2+)表现出荧光淬灭效应,而在相同测试条件下其他金属离子对此探针的荧光则没有影响,因此该探针可对Cu~(2+)选择性识别。     

煤基碳量子点的制备及其在离子检测中的应用

以长焰煤为碳源,使用空气氧化预处理与双氧水氧化结合的"分步法"成功制备出了煤基碳量子点(carbon quantum dot,CQD)。对碳量子点的表面形貌、化学组成和光学性质进行表征,并考察了碳量子点作为纳米荧光探针检测金属离子的性能。结果表明:煤基碳量子点平均粒径为13.1 nm,含氧量达30.56%,在波长为365 nm的紫外光照射下呈现出明亮的青蓝色荧光,其荧光强度在中性条件下最大,并可在较宽的pH范围内保持荧光稳定性;与Fe~(3+)能发生特异性荧光淬灭,在0μmol/L～9μmol/L Fe~(3+)浓度范围内,荧光猝灭程度与Fe~(3+)浓度呈良好的线性关系。     

ZnS量子点荧光探针对Pb~(2+)的检测研究

以L-半胱氨酸修饰ZnS量子点为荧光探针,测定火腿肠中Pb~(2+)含量。对ZnS量子点进行了UV、IR、荧光性能表征。研究了酸度、ZnS量子点浓度对体系荧光强度的影响,最佳测定条件为pH 8,L-半胱氨酸-ZnS量子点(L-ZnS量子点)浓度为1.0×10~(-6)mol/L。基于Pb~(2+)浓度对体系的荧光猝灭效应,实现对Pb~(2+)的定量检测,Pb~(2+)浓度在1.0×10~(-7)~4.5×10~(-5)mol/L范围内与体系的荧光强度线性关系良好,R2=0.984 7,检出限(3σ/S)为3.7×10~(-8)mol/L。线性方程为F0/F=88.14-14.05cPb~(2+),RSD=5.4%(n=6)。该方法简便、灵敏度高,可应用到检测Pb~(2+)诸多方面。     

基于罗丹明B的有机荧光探针合成及Cu~(2+)检测

基于罗丹明B合成了两种有机荧光探针用来检测Cu~(2+)。以罗丹明B与3-甲氧基苯酰肼、水杨酰肼为原料合成了两种探针,命名为Rh1、Rh2,分别与Cu~(2+)以及其它金属离子溶液反应,观察溶液的颜色变化,分别测定其紫外及荧光吸收光谱。Rh1、Rh2加入铜离子溶液后,溶液由无色到粉红色的显著颜色变化,与其它金属离子比较在400～700nm有较明显的紫外-可见吸收和荧光增强。两种荧光探针能够有效的跟Cu~(2+)结合,从紫外-可见吸收光谱和荧光光谱可以看出此探针显示出选择性的、敏感的荧光增强反应,表现出对Cu~(2+)良好的选择性。     

CdTe量子点化学发光法检测多巴胺

制备了巯基丙酸包裹的CdTe量子点,并研究了其在共氧化剂过氧化氢的参与下,碱性介质氢氧化钠中的化学发光行为。结果表明,在过氧化氢为共氧化剂时,CdTe量子点具有很强的化学发光信号。探讨了过氧化氢浓度、氢氧化钠浓度、量子点浓度以及进样顺序对CdTe量子点化学发光信号的影响。利用多巴胺对CdTe量子点/NaOH-过氧化氢发光体系具有抑制作用实现对多巴胺的灵敏检测。该方法在5.0×10~(-5)~1.0×10~(-3)mol·L~(-1)范围内呈良好的线性关系,为化学发光方法检测多巴胺提供了新的方法。     

N-乙酰-L-半胱氨酸修饰的CdTe量子点与人血清白蛋白的相互作用

以N,乙酰-L-半胱氨酸为修饰剂,制备了水溶性的CdTe量子点（NAc—CdTeQDs）。利用荧光光谱法和等温滴定量热法（11℃）研究了NAC-CdTeQDs与人血清白蛋白（HsA）的相互作用。结果表明,NAC—CdTeQDs对HSA内源荧光具有较强的动态猝灭作用,且猝灭作用是扩散控制的。     

Enhanced electrochemiluminescence quenching of CdS:Mn nanocrystals by CdTe QDs-doped silica nanoparticles for ultrasensitive detection of thrombin

This work reports an aptasensor for ultrasensitive detection of thrombin based on remarkably efficient energy-transfer induced electrochemiluminescence (ECL) quenching from CdS:Mn nanocrystals (NCs) film to CdTe QDs-doped silica nanoparticles (CdTe/SiO(2) NPs). CdTe/SiO(2) NPs were synthesized via the St?ber method and showed black bodies' strong absorption in a wide spectral range without excitonic emission, which made them excellent ECL quenchers. Within the effective distance of energy scavenging, the ECL quenching efficiency was dependent on the number of CdTe QDs doped into the silica NPs. Using ca. 200 CdTe QDs doped silica NPs on average of 40 nm in diameter as ECL quenching labels, attomolar detection of thrombin was successfully realized. The protein detection involves a competition binding event, based on thrombin replacing CdTe/SiO(2) NPs labeled probing DNA which is hybridized with capturing aptamer immobilized on a CdS:Mn NCs film modified glassy carbon electrode surface by specific aptamer-protein affinity interactions. It results in the displacement of ECL quenching labels from CdS:Mn NCs film and concomitant ECL signal recovery. Owing to the high-content CdTe QDs in silica NP, the increment of ECL intensity (ΔI(ECL)) and the concentration of thrombin showed a double logarithmic linear correlation in the range of 5.0 aM～5.0 fM with a detection limit of 1aM. And, the aptasensor hardly responded to antibody, bovine serum albumin (BSA), haemoglobin (Hb) and lysozyme, showing good detection selectivity for thrombin. This long-distance energy scavenging could have a promising application perspective in the detection of biological recognition events on a molecular level.     

色氨酸高压在线三维荧光光谱的研究

在Cu2＋与色氨酸物质的量浓度比为0至40范围内,文章用F-2500荧光仪分别对0．1MPa和60MPa条件下酪氨酸三维荧光进行了测量,并对三维荧光光谱的平均值、标准差和重心进行了提取。结果表明：色氨酸的荧光强度随着压力的增加而增加,当压力由0．1MPa变化为60MPa时,纯色氨酸的最大值增加了3．4％。Cu2＋对色氨酸具有猝灭作用,而压力的增加使得色氨酸的猝灭作用减弱,当Cu2＋与色氨酸的物质的量浓度比由0增加到4JD,当压力为0．1MPa的时候,平均值和标准差分别降低了2．1％和2．9％;但当压力为60MPa的时候,平均值和标准差分别降低了1．5％、1．5％。压力从0．1MPa增加到60MPa的时候,色氨酸重心纵坐标增加了2nm。     

Anodic electrogenerated chemiluminescence of quantum dots: size and stabilizer matter

The electrogenerated chemiluminescence (ECL) of semiconductor quantum dots (QDs) is generally believed to be independent of particle sizes or the capping agents used. Herein, we demonstrate that CdTe QDs with different sizes and stabilizers evidently exhibit different ECL behavior in aqueous solution. The ECL of CdTe QDs stabilized by 3-mercaptopropionic acid (MPA) displays two waves at potentials of about +1.17 V and +1.74 V vs. Ag/AgCl, respectively. ECL spectra confirm that the ECL of QDs is attributed to their band gap luminescence, in which the peak positions are changed with QD sizes. The ECL mechanism of CdTe QDs involves superoxide radical generation by reduction of dissolved oxygen at lower potential or water splitting at higher potential. Direct evidence for superoxide radicals in this medium was obtained via electron spin resonance (ESR) experiments. In comparison, the 2-mercaptoethylamine (MEA)-capped CdTe QDs did not exhibit any ECL in air-saturated pH 7.4 PBS. Both ESR and X-ray photon spectroscopy (XPS) experiments revealed that amine groups in MEA-capped QDs were responsible for the absence of ECL. The reaction of an amine group with a superoxide radical leads to the quenching of ECL. The ECL quenching of MPA-capped CdTe QDs was further used to detect melamine. Under the optimum conditions, the inhibited ECL was linear with the logarithm of concentration of melamine within the concentration range of 10(-9) to 10(-5) M and the detection limit was found to be 6.74 × 10(-10) M, which was 100-100?000 times lower than that of the most previous methods.     

Fabrication of fluorescent poly(l‐lactide‐co‐caprolactone) fibers with quantum‐dot incorporation from emulsion electrospinning for chloramphenicol detection

The on‐site rapid detection of antibiotic residues deposited in food or beverage still remains a challenge in daily life. In this study, cadmium tellurium (CdTe) quantum dots (QDs) were incorporated into poly(l ‐lactide‐co‐caprolactone) (PLLACL) fibers with emulsion electrospinning. Water‐soluble CdTe QDs were used as fluorescence agents, and PLLACL was used as filament materials, respectively. A variety of experiments were performed to characterize the structure and properties of the fibrous composite. Ultraviolet–visible and photoluminescence spectra of the fibers showed similar characteristic absorption and emission properties to those of the CdTe QDs. The fibrous QD–PLLACL composite showed stable fluorescence over 30 days at room temperature and could be used to detect chloramphenicol through fluorescence quenching caused by resonance energy transfer. This approach provides a facile shortcut for fabricating fluorescent fibers that simultaneously inherit the mechanical behavior of PLLACL fibers and the fluorescence properties of CdTe QDs for the detection of antibiotics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44584.     

CdTe量子点的纯化以及作为pH探针的研究

以巯基乙酸为稳定剂在水相中合成了CdTe量子点,并将合成的CdTe量子点进行表征、纯化。通过用0.05 mol.L-1PBS缓冲溶液调节不同的pH来考察量子点的荧光强度和pH的关系。研究发现,水溶性的CdTe量子点是pH敏感的,随着pH值的降低,量子点荧光强度的下降规律与溶液pH值呈现良好的线性关系。结果表明,CdTe量子点是一个令人满意的pH敏感的探针,有潜在的化学和生物传感能力。     

Studies on the interaction of CdTe QDs with bovine serum albumin

BACKGROUND: Quantum dots (QDs) have attracted much attention in biological and medical applications. In particular, the interaction of QDs with bovine serum albumin (BSA) is crucial, and has been systematically investigated by various spectroscopic techniques under the physiological conditions. RESULTS: The effects of ionic strength and pH on the interaction of CdTe QDs with BSA were studied by changing NaCl concentration and pH in mixed solution and making fluorescence spectroscopic measurements. The Stern‐Volmer quenching constant (K_a) of different ionic strength and pH were calculated, and information on the structural features of BSA were discussed by means of circular dichroism (CD) spectrum. CONCLUSION: Both fluorescence (FL) and circular dichroism (CD) results indicated that hydrophobic and electrostatic interactions play a major role in the binding reaction, and the nature of quenching is static, resulting in forming QDs‐BSA complexes. Copyright © 2012 Society of Chemical Industry     

碲化镉量子点与金纳米粒子用于DNA检测

A DNA fluorescence probe system based on fluorescence resonance energy transfer （FRET） from CdTe quantum dot （QD） donors to Au nanoparticle （AuNP） acceptors is presented. CdTe QDs, 2.5nm in diameter, as energy donors, were prepared in water. Au nanoparticles, 16nm in diameter, as energy acceptors, were prepared from gold chloride by reduction. CdTe QDs were linked to 5＇-NH2-DNA through 1-ethyl-3-（dimethylaminopropyl）car- bodiimide hydrochloride （EDC） as a linker, and the 3＇-SH-DNA was self-assembled onto the surface of AuNPs. The hybridization of complementary double stranded DNA （dsDNA） bound to the QDs and AuNPs （CdTe-dsDNA-Au） determined the FRET distance of CdTe QDs and Au nanoparticles. Compared to the fluorescence of CdTe-DNA, the fluorescence of CdTe-DNA-Au conjugates decreased extremely, which indicated that the FRET occurred between CdTe QDs and Au nanoparticles. The fluorescence change of this conjugate depended on the ratio of Au-DNA to CdTe-DNA. When the AuNPs-DNA to QD-DNA ratio was 10：1, the FRET efficiency reached a maximum. The probe system would have a certain degree of fluorescence recovery when a complementary single stranded DNA was introduced into this system, which showed that the distance between CdTe QDs and Au nanoparticles was increased.     

A fast synthesis of near-infrared emitting CdTe/CdSe quantum dots with small hydrodynamic diameter for in vivo imaging probes

Highly luminescent near-infrared (NIR) emitting CdTe/CdSe quantum dots (QDs) were prepared through a fast and convenient method, and a new type of multivalent polymer ligands was used as the surface substituents to prepare highly stable hydrophilic QDs with small sizes. The well-defined CdTe/CdSe QDs were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy and photoluminescence (PL) spectroscopy, respectively. The as-prepared CdTe/CdSe QDs were photostable with high PL quantum yields (QYs) (up to 66% at room temperature), low toxicity to cells at experimental dosages, and the QDs' fluorescence emissions were tunable between 700 and 820 nm. Furthermore, fluorescence imaging using CdTe/CdSe QDs conjugated with the AS1411 aptamer (targeting nucleolin) probe in cancer cells was reported, and the CdTe/CdSe QDs were also successfully applied for the fluorescence imaging of living animals. Our preliminary results illustrated that the CdTe/CdSe NIR-QDs with small sizes would be an alternative probe for ultrasensitive, multicolor, and multiplex applications, especially for in vivo imaging applications.