木质素碳纳米酶的制备及用于检测人尿液中多巴胺

以木质素磺酸钠为碳源,水热法合成了MoS2掺杂的碳纳米酶(Mo, S-CDs),并基于其过氧化物酶特性,将其用于检测人尿中多巴胺的含量。对纳米酶的形貌进行了表征。结果显示,Mo, S-CDs为球型,直径在2 nm左右,在水中能够较好的分散;红外图谱结果表明Mo, S-CDs表面官能团丰富;X射线光电子能谱表明Mo, S-CDs中存在Mo, S, C, O元素。Mo, S-CDs具有稳定、高效的过氧化物酶催化活性,可催化H₂O₂与3,3’,5,5’-四甲基联苯胺(TMB)反应,生成氧化产物oxTMB。蓝色的oxTMB可被多巴胺还原回TMB,导致系统在oxTMB特征峰处的吸光度下降。因此,基于Mo, S-CDs对H₂O₂的传感能力构建了多巴胺-Mo, S-CDs的催化传感体系,并用于检测人尿液中多巴胺的含量。多巴胺浓度在0.5～20μmol/L范围内有良好的线性关系,检出限为0.0639μmol/L,回收率为96.5%～101.7%,相对标准偏差(RSD)<5%。     

基于智能手机传感平台的纳米酶比色法用于葡萄糖的快速检测

葡萄糖的定量检测在人体健康监测和慢性病管理方面具有非常重要的意义.目前,血液中的葡萄糖(血糖)检测主要采用基于葡萄糖氧化酶(Glucose oxidase,GOx)的比色法,因其操作简单、现象直观而应用广泛.但是,显色体系信号的读出常需要借助生化分析仪和酶标仪等仪器,需要熟练的专业人员进行操作和数据分析,因此限制了其在基层医疗部门和不发达地区的使用.本研究构建了基于具有类过氧化酶活性的四氧化三铁纳米颗粒(Fe3O4 NPs)辅助的比色法检测血糖浓度.GOx催化葡萄糖生成过氧化氢(H2O2),Fe3O4 NPs进一步催化H2O2 氧化底物3,3′,5,5′-四甲基联苯胺(TMB)生成蓝色产物,最后通过基于智能手机的便携式检测设备实现数据的自动分析.本方法的线性响应范围为1～30 mmol/L,检出限为0.366 mmol/L.将本方法用于20组临床血清样本的检测,检测结果与酶标仪和医院提供的数据具有很好的一致性.Fe3O4纳米酶具有催化活性高、稳定性好、易分离以及可回收利用的优点,且智能手机易操作,具有强大的图像采集与运算能力,可高度集成,显著降低了仪器成本,为血糖的快速比色检测提供了一种有效工具.     

基于金属有机骨架的纳米酶及其应用研究进展

金属有机骨架（MOFs）具有大量的活性位点,且其框架结构可以保护其中包裹的天然酶不被破坏,从而具有模拟天然酶的性质。因此,基于MOF的纳米酶被认为具有良好的发展潜力。MOF基纳米酶分为四大类：分别是单纯MOFs、改性MOFs、与天然酶复合的MOFs以及MOF衍生物。种类的多样性同时也造就了制备、性能以及应用的多样性,这些内容在此综述中将被详细阐述。     

基于聚多巴胺纳米粒子的荧光增强型探针检测乙酰胆碱酶

以多巴胺盐酸盐为原料,在碱性条件下通过氧化反应制备聚多巴胺荧光纳米粒子(F-PDA),再与二氧化锰(MnO2)纳米片进行复合,构建了用于检测乙酰胆碱酶(AChE)的F-PDA@MnO2复合物荧光探针。MnO2纳米片和F-PDA复合,体系的荧光被猝灭。在底物乙酰硫代胆碱(ATCh)存在下,加入AChE后,体系荧光恢复,恢复程度与AChE浓度在5.0~100mU/mL范围内呈良好的线性关系,检出限为0.14mU/mL(S/N=3)。该方法用于缓冲溶液中AChE的检测,加标回收率为89.5%~120%,相对标准偏差为1.6%~2.5%,且具有较高的选择性。可为基于F-PDA传感体系构建提供新的方法学模型。     

纳米银比色法检测多巴胺

在银纳米粒子存在下, 多巴胺可还原硝酸银生成银, 导致银纳米粒子粒径增大, 从而使溶液颜色发生改变. 基于此, 提出了一种用于检测多巴胺的纳米银比色法. 随着多巴胺浓度的增大, 溶液的颜色由浅黄色逐渐变为深黄色, 银纳米粒子溶液的吸收峰发生红移且吸光度增大. 在最优实验条件下, 该方法检测多巴胺的线性范围为0.05~16 μmol/L, 检出限为0.04 μmol/L. 该方法操作简单、 灵敏且选择性良好, 可用于人血清中多巴胺的检测.     

锰/锆-双金属有机骨架纳米酶比色法检测水中痕量氟

该文设计合成了一种新型锰/锆-双金属有机框架（Mn/Zr-MOF）纳米材料,并用于水中痕量氟的检测。顺磁性金属锰、锆赋予了Mn/Zr-MOF类过氧化物酶活性,而锆金属能选择性识别氟离子（F^-）。Mn/Zr-MOF可催化过氧化氢氧化3,3',5,5'-四甲基联苯胺（TMB）生成蓝色oxTMB,其最大吸收波长为652nm。体系中的F^-可与锆特异性结合,并抑制Mn/Zr-MOF的催化活性,使体系颜色变浅。F^-质量浓度与652nm处的吸光度呈负相关关系,据此建立了一种检测F^-的比色法。方法的线性范围为0.40~5.0mg/L,检出限为0.16mg/L。将该方法应用于实际水样中F^-测定,加标回收率为97.6%~106%,相对标准偏差为0.27%~5.2%。该方法快速、灵敏、选择性好,在实际样品分析中具有较大潜力。     

基于纳米酶的比色传感器检测重金属的研究进展

重金属污染严重威胁人体健康和生态系统安全,实现简便、快速地检测重金属,是有效监测污染状况的关键。与天然酶相比,纳米酶具有活性稳定、成本低等优点。基于纳米酶构建的比色传感器已引起诸多学者的广泛关注,逐渐成为检测重金属的常用方法之一。为此,简要概述了比色传感器的原理、比色方法和纳米酶材料分类及其类酶活性,重点综述了纳米酶比色传感器在重金属检测领域的研究进展,并展望了其实际应用中所面临的挑战与未来的发展方向（引用文献70篇）。     

基于金属有机骨架衍生多孔碳材料用于同时检测对乙酰氨基酚和盐酸多巴胺

以金属有机骨架(MOFs)作为模板,在氮气氛下对其进行热处理,合成了一种金属有机骨架衍生多孔碳材料(MOFs Pyrolysis Porous Carbon,MPPC).通过扫描电镜(SEM)、X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、拉曼光谱及N2吸附-脱附测试,对其形貌和结构进行了表征.采用滴涂法将MP...     

Highly selective colorimetric sensor for cysteine and homocysteine based on azo derivatives

A simple colorimetric method for the determination of cysteine and homocysteine has been developed. The reaction of the azo dyes containing an aldehyde group with cysteine or homocysteine afforded very stable derivatives thiazolidines or thiazinanes under neutral pH conditions. The method is selective and sensitive for cysteine and homocysteine detection without the interference of other amino acids. Importantly, the recognition of Cys and Hcy could be observed by naked eyes.     

Dual-mode Detection of Dopamine Based on Enhanced Fluorescent and Colorimetric Signals of Fe3+-H2O2-o-Phenylenediamine System

A fluorescent and colorimetric dual-mode “light-on” assay for the detection of dopamine (DA) was developed based on Fe³⁺-H₂O₂-OPD system. In general, Fe³⁺ could catalyze the H₂O₂-mediated oxidation of colorless and nonfluorescent o-phenylenediamine (OPD), and the resultant 2,3-diaminophenazine (DAP) exhibits a visible yellow color and yellow fluorescence. However, the reaction rate is extremely slow. By comparison, the introduction of DA can trigger a typical Fenton reaction that generates hydroxyl radical (?OH) continuously, thus increasing the conversion rate of OPD to DAP. Correspondingly, both color and fluorescence of the sensing system are enhanced obviously. On the basis of this fact, a sensor with dual readout for the detection of DA was established via measuring the fluorescent and colorimetric signals of the Fe³⁺-H₂O₂-OPD system. The linear ranges were 0.05–20 mM and 0.10–18 mM, and the detection limits were calculated to be 15 and 65 nM (S/N = 3) for fluorescent and colorimetric detection, respectively. The proposed dual-readout method features with simplicity, high sensitivity, visualization and good accuracy. Moreover, the method has been successfully applied to the detection of DA in human urine with satisfactory results.     

Evaluation of the oxidase like activity of nanoceria and its application in colorimetric assays

Nanomaterial-based enzyme mimics have attracted considerable interest in chemical analysis as alternative catalysts to natural enzymes. However, the conditions in which such particles can replace biological catalysts and their selectivity and reactivity profiles are not well defined. This work explored the oxidase like properties of nanoceria particles in the development of colorimetric assays for the detection of dopamine and catechol. Selectivity of the system with respect to several phenolic compounds, the effect of interferences and real sample analysis are discussed. The conditions of use such as buffer composition, selectivity, pH, reaction time and particle type are defined. Detection limits of 1.5 and 0.2 μM were obtained with nanoceria for dopamine and catechol. The same assay could be used as a general sensing platform for the detection of other phenolics. However, the sensitivity of the method varies significantly with the particle type, buffer composition, pH and with the structure of the phenolic compound. The results demonstrate that nanoceria particles can be used for the development of cost effective and sensitive methods for the detection of these compounds. However, the selection of the particle system and experimental conditions is critical for achieving high sensitivity. Recommendations are provided on the selection of the particle system and reaction conditions to maximize the oxidase like activity of nanoceria.     

Tree-shaped paper strip for semiquantitative colorimetric detection of protein with self-calibration

This paper described a convenient semiquantitative method for colorimetric detection of protein with self-calibration integrated on the test strip. Hydrophilic paper was employed as microfluidic device for running colorimetric assay, tree-shaped design was developed to ensure uniform microfluidic flow for multiple branches. The approach was validated with bovine serum albumin (BSA) colorimetric detection, and colorimetric results observed by naked eyes were consistent with that from apparatus. The device could be coupled with digital transmission of images for remote monitoring system for diagnosis, food control, and environmental analysis.     

The synthesis and recognition properties of colorimetric fluoride receptors bearing sulfonamide

Two artificial receptors, 1,2-bis-p-substituted phenyl-sulfonamido-4,5-bis-nitrobenzene, have been designed and synthesized. The interactions of these receptors with halide anions are determined by UV-vis and ¹H NMR titration experiments. Results indicate that two receptors have strong sensitivity and selectivity for fluoride among halide anions. In addition, the visible color changes upon the addition of fluoride anion can make the receptors as convenient detection tools for fluoride anion.     

A new colorimetric platform for ultrasensitive detection of protein and cancer cells based on the assembly of nucleic acids and proteins

An amplified colorimetric method has been developed for the detection of protein and cancer cells based on the assembly of nucleic acids and proteins for the first time. In this process, the assembly of nucleic acids was triggered by a biotinylated DNA strand after a sandwich immunoreaction. The biotinylated DNA strand and sandwich immunocomplex were connected by streptavidin. Then, the assembly of biotinylated bovine serum albumin (Biotin-BSA) and streptavidin-horseradish peroxidase (SA-HRP) occurred at a node of the assembled products of nucleic acids through the biotin-streptavidin reaction. Under the catalysis of horseradish peroxidase, 3,3′,5,5′-tetramethylbenzidine (TMB) was oxidized by H₂O₂ and the oxidized product was analyzed by its UV–vis absorbance signal and sensitive colorimetric detection. This colorimetric sensor could not only achieve the quantitative determination of protein by UV–vis absorbance but could also be applied for semiquantitative determination by digital visualization. Using alpha-fetoprotein (AFP) as the model target, this proposed colorimetric method showed a wide linear range from 5 pg/mL to 1 ng/mL with a detection limit of 1.95 pg/mL by the instrument, and even 5 pg/mL target protein could be distinguished simply by the naked eye. This approach was then expanded to detect cancer cells based on the recognition of folic acid receptors that were over-expressed on the cancer cells by folic acid-tethered DNA. More importantly, this strategy can be further used as a universal colorimetric method for the determination of viruses or other proteins by changing the corresponding antibodies.     

Determination of orthophosphates using a macro segmented flow analyzer (MSFA) based on colorimetric detection

Fabrication of a macro segmented flow analysis (MSFA) system based on reconfiguration of the manifold by adjustment of the sample/reagent ratio, has been found to produce a sensitive method for orthophosphate analysis based on colorimetric detection at 880 nm. Optimization of sample tube length, reaction temperature and molybdate concentration in the carrier solutions has been carried out. The larger sample tube internal diameter led to the combined advantages of better sensitivities, wider working range and higher sample throughput over most existing methods. Using the optimized conditions of 50.0 cm sample tube length (1.6 mm i.d.), 37.0 °C reaction temperature and 0.0113 M molybdate concentration in the carrier solution, the calibration model for orthophosphate standard solutions was found to be linear (y = 0.04895x + 0.003561; correlation coefficient, r²=0.9970) over the working range 0.01-2.00 mg l⁻¹ orthophosphate. The volume of the sample injected was 1.396 ml at a flow rate of 6.0 ml min⁻¹. The sample throughput of this MSFA method was 40 samples per an hour, with a detection limit of 4.0 μg l⁻¹, and %R.S.D.’s below 5%. The MSFA method was successfully applied to analysis of water and wastewater samples.     

Reaction detector with three dimensional coiled open tubes in HPLC

Summary A reaction detector with non-segmented flow in open tubes as reaction track is described. To minimize peak broadening the open tubes are arranged in a three dimensional coiled structure by knitting. At low volume flow rates the h-values in these open tubes are independent of flow rate and are significantly lower than predicted by theory. The applicability of this reactor for classical colorimetric detection with corrosive reagents is shown.Part of Ph. D. Thesis, Saarbrücken 1976