基于碳量子点过氧化物模拟酶的肌氨酸比色测定

以果皮为原料制备了水溶性碳量子点(CQDs), 透射电子显微镜分析表明其平均粒径为2.4 nm; 红外光谱分析证实CQDs表面富含含氧官能团. 所得CQDs可催化H₂O₂氧化3,3',5,5'-四甲基联苯胺(TMB)生成蓝色氧化产物(ox-TMB). 基于上述反应, 建立了测定H₂O₂的分析方法, 在pH=3.5, 温度40 ℃, TMB浓度为1.0 mmol/L及孵育时间15 min的条件下, 当H₂O₂浓度在5.0~100 μmol/L范围时, ox-TMB的吸光度随H₂O₂浓度的升高而线 性增强, 方法的检出限为3.0 μmol/L. 鉴于H₂O₂是肌氨酸氧化酶催化肌氨酸氧化的产物之一, 建立了CQDs催化H₂O₂氧化TMB间接测定肌氨酸的分析方法. 结果表明, 当肌氨酸浓度在0.5~350 μmol/L范围内时, 吸光度 与其浓度呈良好的线性关系, 方法的检出限为0.3 μmol/L; 将该方法应用于人体尿样的测定, 回收率为94%~99%.     

炭-/石墨烯量子点在超级电容器中的应用

炭-/石墨烯量子点作为新兴的炭纳米材料,因具有独特的小尺寸效应和丰富的边缘活性位点而在高性能超级电容器电极材料的研发方面展现出巨大潜力。针对目前炭-/石墨烯量子点在超级电容器电极材料方面的应用优势和存在的关键问题,本文以炭-/石墨烯量子点、量子点/导电炭复合材料、量子点/金属氧化物复合材料、量子点/导电聚合物复合材料以及量子点衍生炭这些电极材料为脉络,梳理了近年来该领域的发展状况,尝试阐释炭-/石墨烯量子点在电极材料、复合材料和衍生炭电极材料中所起到的关键作用,最后对炭-/石墨烯量子点电极材料的发展进行了展望。本综述以期为炭-/石墨烯量子点基电极材料的研究提供一定参考和依据。     

Biomass-based Carbon Dots as Peroxidase Mimics for Colorimetric Detection of Glutathione and L-Cysteine

Biomass-carbon dots(named as B-CDs) have been successfully prepared via facile one-step hydrothermal reflux treatment at a low temperature from passion fruit peel. The as-prepared B-CDs had a uniform sphere morphology and size of 1-3 nm, which possessed rich nitrogen/oxygen-containing functional groups. B-CDs could imitate peroxidase and accelerate the reaction process of H₂O₂ oxidizing the substrate 3,3',5,5'-tetramethylbenzidine(TMB), which caused an obvious color change in the solution due to the oxidization of achromic TMB into blue oxidation product(ox-TMB) with an absorption peak at 652 nm. Furthermore, the product could be further reduced to native colorless TMB by the reducing agent glutathione or L-Cysteine. Thus, depending on the peroxidase-like properties of B-CDs, we developed a colorimetric approach to detecting both glutathione and L-Cysteine, which showed superior selective and sensitive detection towards glutathione and L-Cysteine in a linear range of 0-20 µmol/L. The limits of detection were 0.62 and 0.58 µmol/L, respectively.     

基于碳量子点的光电器件应用新进展

碳量子点(CQDs)作为一种新型荧光碳纳米材料,由于其较高的电子迁移率、较长的热电子寿命、极快的电子取出速度,可调的带隙宽度、较强的稳态荧光等独特的光电性质和可溶液加工、成本低廉的特点,使得CQDs在光电器件领域具有广阔的应用前景,近年来受到人们的广泛关注,重要的研究成果不断涌现。本文首先简要介绍了CQDs的合成方法、化学结构及其光电性质,然后总结了CQDs在发光二极管(LEDs)、太阳能电池(SCs)和光电探测器(PDs)等光电器件领域的研究进展,最后对CQDs的发展方向进行了展望。     

碳点的合成及对锰离子的比色检测——推荐一个大学化学综合实验

In this experiment, carbon dots were prepared by hydrothermal method with citric acid as raw material. The colorimetric detection of Mn²⁺ was realized via the catalytic oxidation discoloration of Mn²⁺ to 3, 3', 5, 5'-tetramethylbenzidine (TMB) in the mixed system of carbon dots and TMB. Selectivity and sensitivity of the detection were studied by UV-Vis absorption spectrum. This comprehensive experiment covers the preparation and characterization of nanomaterials and the analysis and detection to important substances. It not only exercises students' comprehensive ability to use knowledge and experimental skills, but also helps to broaden students' academic vision.     

氮硫共掺杂碳量子点对胃液pH值的精确检测

以水杨酸和硫脲为原料,通过水热法一步合成水溶性好、稳定性强、量子产率高(36.23%)、呈蓝光的氮硫共掺杂碳量子点(N,S-CQDs).在302 nm波长激发下,N,S-CQDs在发射波长409 nm处的荧光强度与pH值(在2.01～5.11范围内)线性关系良好,相关系数为0.9931,可原位、实时检测胃液内pH值在Δ0.01范围内的变化.可用于胃癌早期诊断和新生儿健康防护.400μg/m L N,S-CQDs孵育铜绿微囊藻细胞48 h,存活率82.8%,其可作为人体胃细胞荧光探针,经人体排泄进入水环境,对淡水浮游生物毒性低,环境友好.     

Synthesis of MnO2/MWNTs Nanocomposites Using a Sonochemical Method and Application for Hydrazine Detection

A sonochemical method has been successfully used to synthesize MnO₂/MWNTs nanocomposites. The structure and nature of the resulting MnO₂/MWNTs composite were characterized by scanning electron microscopy (SEM), energy‐dispersive X‐ray diffraction (EDX), X‐ray photoelectron spectroscopy (XPS).The results show that the sonochemically synthesized MnO₂ nanoparticles were homogeneously dispersed on the modified MWNT surfaces. The performance of the MnO₂/MWNTs nanocomposites modified electrode was characterized using cyclic voltammetry (CV) and Nyquist plots. The electrode exhibits efficient electron transfer ability and high electrochemical response towards hydrazine. This may be attributed to the small particle size, high dispersion of MnO₂ particles. The fabricated hydrazine sensor showed a wide linear range of 5.0×10^?7–1.0×10^?3 M with a response time less than 5 s and a detection limit of 0.2 μM. Taking the advantage of the unique properties of both MWNTs and MnO₂, it would greatly broaden the applications of MWNTs and MnO₂.     

Nanozyme Based on Dispersion of Hemin by Graphene Quantum Dots for Colorimetric Detection of Glutathione

Compared with natural enzymes, nanozymes have the advantages of good catalytic performance, high stability, low cost, and can be used under extreme conditions. Preparation of highly active nanozymes through simple methods and their application in bioanalysis is highly desirable. In this work, a nanozyme based on dispersion of hemin by graphene quantum dot (GQD) is demonstrated, which enables colorimetric detection of glutathione (GSH). GQD was prepared by a one-step hydrothermal synthesis method. Hemin, the catalytic center of heme protein but with low solubility and easy aggregation that limits its catalytic activity, can be dispersed with GQD by simple sonication. The as-prepared Hemin/GQD nanocomplex had excellent peroxidase-like activity and can be applied as a nanozyme. In comparison with natural horseradish peroxidase (HRP), Hemin/GQD nanozyme exhibited a clearly reduced Michaelis–Menten constant (K_m) when tetramethylbenzidine (TMB) was used as the substrate. With H₂O₂ being the substrate, Hemin/GQD nanozyme exhibited a higher maximum reaction rate (V_max) than HRP. The mechanisms underlying the nanozyme activity were investigated through a free radical trapping experiment. A colorimetric platform capable of sensitive detection of GSH was developed as the proof-of-concept demonstration. The linear detection range was from 1 μM to 50 μM with a low limit of detection of 200 nM (S/N = 3). Determination of GSH in serum samples was also achieved.     

石墨烯量子点-银纳米颗粒复合物用于过氧化氢和葡萄糖比色检测

以石墨烯量子点(GQDs)为还原剂和稳定剂,在其表面原位生长银纳米粒子(AgNPs),制备了具有良好分散性的GQDs/AgNPs纳米复合物,其粒径小于30 nm.GQDs/AgNPs纳米复合物具有类过氧化物酶的催化活性,能有效催化H2O2氧化3,3',5,5'-四甲基联苯胺(TMB)并发生显色反应.稳态动力学分析表明,GQDs/AgNPs催化动力学遵循典型的Michaelis-Menten模型,其催化机理符合乒乓机制.与辣根过氧化物酶(HRP)相比,GQDs/AgNPs纳米复合物具有更强的亲和性.基于GQDs/AgNPs的催化活性和葡萄糖氧化产生H2O2的原理,建立了H2O2和葡萄糖的比色检测方法,检出限分别为0.18和1.6 μmol/L.将本方法应用于血浆中葡萄糖的检测分析,结果与标准方法相符.     

基于碳量子点荧光探针测定法莫替丁的研究

以木炭为碳源,采用回流的方法制备了碳量子点。用荧光光谱、紫外光谱法研究了该碳量子点与法莫替丁的相互作用。实验发现,在pH为7.1的Tris-HCl缓冲溶液中,法莫替丁的加入可使碳量子点荧光信号显著增强,其浓度在8.0×10~(-9)~1.0×10~(-7) mol/L范围内与碳量子点荧光信号强度的增加值△F呈良好的线性关系,相关系数r为0.9993。据此,提出了以碳量子点为荧光探针测定法莫替丁的新方法,方法检出限(3s/k)为2.0×10~(-9) mol/L。该方法简便、快捷、灵敏,应用于样品中法莫替丁含量的测定,回收率范围为98.50%~103.2%。     

基于CdTe量子点测定烟酸诺氟沙星的新方法研究

以巯基乙酸修饰的CdTe量子点(QDs)为荧光探针, 考察了不同条件下烟酸诺氟沙星对CdTe QDs荧光的猝灭作用. 发现在磷酸缓冲液中(PBS, pH 7.40, 0.10 mol/L), 其猝灭作用最强, 随后对其猝灭机理进行了讨论. 在此基础上建立了基于荧光猝灭法检测烟酸诺氟沙星含量的新方法, 该方法的线性范围为0.10～90 μg/mL, 线性方程为DF＝26.6206c－20.8273 (μg/mL), 相关系数r为0.997, 检测限(3S/N)为2.50×10^－2 μg/mL. 应用此法检测兽药雏乐宝、烟酸氟哌酸和强效氟哌酸中烟酸诺氟沙星的含量, 百分标示量在93.0%～104.0%范围内变化, 相对标准偏差(RSD)≤4.2%|与常用的紫外分光光度法相比, 该法具有准确度高、灵敏度高且检测范围宽等优势, 显示出潜在的应用前景.     

Synthesis of Fluorescent Carbon Quantum Dots from Dried Lemon Peel for Determination of Carmine in Drinks

Carbon quantum dots(CQDs) with a quantum yield of 11% were synthesized via a simple, low-cost and green hydrothermal treatment using dried lemon peel as carbon source. The obtained CQDs showed a strong emission at the wavelength of 505 nm with an optimum excitation of 425 nm. Carmine with maximum absorption wavelength at 508 nm could selectively quench the fluorescence of CQDs. Based on this principle, a fluorescence probe was developed for carmine determination. The quenching mechanism of CQDs was elucidated. A linear relationship was found in the carmine concentration range of 0.20—30.00 mg/L with the detection limit(3σ/k) of 0.16 mg/L. Satisfactory results were achieved when the method was applied for the determination of carmine in soft drinks.     

碳量子点阳离子表面活性剂的多功能性

碳量子点以其多彩的荧光及廉价而丰富的制备原料引起人们的广泛兴趣。至今,已有大量关于碳量子点制备及其荧光性能直接利用的文献报道。若采用恰当的方法对碳量子点进行化学修饰,则可以将其转化为实用的精细化学品,从而拓展碳量子点的应用领域。本文报道了一种碳量子点阳离子表面活性剂的制备方法。首先,乙二胺四乙酸、二乙胺及双氧水的混合水溶液经水热处理,获得碳量子点(以OX-CQDs表示),再以氯代正构十二烷对其进行季铵化修饰,获得新型碳量子点阳离子表面活性剂(以OX-CQDs-C₁₂H₂₅表示)。OX-CQDs-C₁₂H₂₅具有良好的降低水的表面张力和减小水接触角的能力,水的界面张力能降低至26.7 mN∙m⁻¹,其性能超过了一些新型的Gemini型阳离子表面活性剂;季铵化的修饰也大大提高了OX-CQDs对大肠杆菌的抑菌能力,低至0.41 mg∙mL⁻¹的OX-CQDs-C₁₂H₂₅溶液其抑菌率接近100%。表面活性剂,抑菌性和荧光性能赋予了OX-CQDs-C₁₂H₂₅的多种功能性。     

基于碳量子点光活性模拟酶性能灵敏检测焦磷酸根离子

利用简单的水热法合成了具有良好水溶性、优良光活性模拟酶性质的碳量子点(CDs),该量子点在可见光照(λ≥400 nm)下可以催化氧化辣根过氧化物酶(HRP)的特征底物3,3,5,5-四甲基联苯(TMB),生成与HRP催化氧化相同的产物。铜离子可与CDs发生配位作用,使CDs聚集光诱导模拟酶的活性降低;焦磷酸根(ppi)存在时,铜离子与ppi配位生成Cu~(2+)-ppi复合物,从而使CDs分散模拟酶活性恢复。利用这一现象建立了一种比色检测ppi的方法,在最佳条件下,检测信号与ppi的浓度之间存在良好的线性关系,其线性范围为1.0×10~(-6)~5.0×10~(-3)mol/L,检出限为2.5×10~(-7)mol/L。将该方法应用于健康人血浆中ppi的检测,ppi的回收率为97.4%~104.8%,研究表明该比色传感器可用于人血浆中ppi的检测。     

Colorimetric Detection of Glucose Using WO3 Nanosheets as Peroxidase-mimetic Enzyme

In the present work, WO₃ nanosheets(WO₃ NSs) were prepared by a facile method at room temperature. The obtained WO₃ NSs showed peroxidase-like activity, which could catalyze 3,3',5,5'-tetramethylbenzidine(TMB) to form a blue oxidation product(ox TMB) in the presence of H₂O₂. Based on this, convenient and sensitive colorimetric methods for the detection of H₂O₂ and glucose were established. The linear ranges for detecting H₂O₂ and glucose were 1-200 μmol/L and 1-100 μmol/L, respectively. The limits of the detection of H₂O₂ and glucose were as low as 0.79 and 0.96 μmol/L, respectively. This method was also successfully applied to the detection of glucose in urine samples. The detection result was consistent with that of the value detected by the clinical method, indicating the potential in clinical diagnosis and biomedical detection.     

类石墨相氮化碳量子点（g-CNQDs）用于水质中三硝基苯酚的检测

基于类石墨相氮化碳量子点( g-CNQDs)建立了一种高效、灵敏、简单的荧光化学传感器用于检测水相中的三硝基苯酚( TNP)。 g-CNQDs是一种新型纳米半导体材料,具有很好的水溶性、生物相容性、环境友好、良好荧光特性,无毒性,通过简单的固相反应法,制备了g-CNQDs材料,探讨了g-CNQDs与TNP之间的相互作用(如仔-仔共轭作用、氢键相互作用和静电作用)引起的g-CNQDs荧光猝灭过程。此荧光传感器响应速度快,对TNP具有良好的选择性。实验结果表明,本方法在0.1~100 nmol/L和0.1~100μmol/L的浓度范围内呈现良好的线性关系,检出限为0.05 nmol/L ( S/N=3)。 g-CNQDs材料在化学传感器方面有很好的应用前景,利用此荧光传感器对实际水样中的TNP进行了检测,为监测水环境中TNP提供了新方法。     

CdSe量子点探针共振光散射法检测溶菌酶

基于CdSe量子点与溶菌酶之间的相互作用, 采用共振光散射法建立了简单快速检测溶菌酶的新方法. 在优化的实验条件下, 当溶菌酶浓度在0.01~0.8 μmol/L范围内变化时, 散射光强度与溶菌酶浓度间呈现良好的线性关系, 相关系数为0.9960. 此方法对溶菌酶的检出限为5.2 nmol/L, 对0.09 μmol/L溶菌酶5次平行测定的相对标准偏差为2.1%, 此方法选择性较好, 常见离子、蛋白质及常见氨基酸对溶菌酶检测干扰较小, 这种新方法已被用于合成样品中溶菌酶的检测, 并取得较好结果. 为进一步考察CdSe量子点与溶菌酶之间的相互作用, 进行了圆二色光谱、透射电子显微镜和荧光寿命表征研究, 结果表明, CdSe量子点与溶菌酶的结合不仅使溶菌酶的构象发生变化, 也使CdSe量子点的分散状态和荧光寿命发生了改变.     

CdTe/CdS半导体量子点作为农药百草枯的高灵敏传感器

用硫普罗宁(Tiopronin, TP)作为稳定剂合成了水溶性的高荧光CdTe/CdS量子点. 研究了该量子点与10种农药的相互作用. 实验发现, 当农药浓度为4.76×10^-6 mol/L时, 农药百草枯(Paraquat)能显著猝灭CdTe/CdS量子点的荧光, 使其荧光强度下降87.3%, 而分别加入乙酰甲胺磷及辛硫磷等其它9种农药, 仅能使CdTe/CdS量子点的荧光强度下降0.1%～5.1%, 显示了该CdTe/CdS量子点对百草枯的特异性传感作用. 采用吸收光谱和时间分辨荧光动力学研究了百草枯对CdTe/CdS量子点的荧光猝灭机理. 计算得出荧光强度猝灭的Stern-Volmer常数K为2.03×10⁶, 而寿命猝灭的Stern-Volmer常数K为4.25×10⁵. 结果表明, 百草枯对CdTe/CdS量子点的荧光猝灭主要为静态过程, 而动态过程的贡献较小. 利用二者的猝灭作用建立了对农药百草枯的高灵敏检测新方法, 校正曲线的线性范围为9.90×10^-9～1.50×10^-6 mol/L, 检出限为6.35×10^-9 mol/L, R=0.999. 用该方法对3种食品和3种水样中残留农药进行了检测, 加标回收率均在82.2%～98.5%之间, 其相对标准偏差为2.62%~8.35%.     

Synthesis of Carbon Quantum Dots Nanoparticles by Cyclic Voltammetry and Its Application as Methanol Tolerant Oxygen Reduction Reaction Electrocatalyst

Carbon quantum dot (CQD) nanoparticles are synthesized by one‐step electrochemical method, cyclic voltammetry (CV), at different potentials using graphite rods and NaOH/EtOH as electrolyte. The electro‐chemically manufactured CQD is characterized by Transmission electron microscopy, Ultra violet absorption, X‐ray diffraction and Fourier transform infrared spectrometry. The morphology and microstructure methods confirm the formation of high quality CQD. Finally, we design a new gas diffusion electrode (GDE) based on CQD pasted on carbon paper for the oxygen reduction reaction at cathode side as methanol tolerance in direct methanol fuel cell and compared it with standard Pt‐C catalysts using cyclic voltammetry and linear sweep voltammetry. The ORR results in presence of methanol indicate that the GDE prepared from CQD exhibits methanol tolerance compared to the GDE prepared from Pt/C (Electrochem).     

基于红色碳量子点的荧光法快速检测饮料中的胭脂红

该研究以红色碳量子点为荧光探针,建立了一种饮料中胭脂红的荧光快速检测方法,以满足食品着色剂胭脂红的检测需求.首先以对苯二胺为碳源,于180℃水热反应合成红色碳量子点(RCDs).研究发现所制备的RCDs的荧光发射峰与胭脂红的紫外可见吸收峰明显重叠,且两者之间存在内滤效应.基于内滤效应机理,建立了一种对胭脂红定量检测的荧...