ZIF-8封装AuNCs荧光传感器用于铁离子的检测

介绍一个适合于本科教学使用的综合创新实验,设计合成了一种荧光传感器Au NCs@ZIF-8,并将其用于铁离子(Fe^(3+))的检测。MOFs具有高效吸附、聚集检测物的特点,因此选择将Au NCs封装到ZIF-8中,从而实现目标物的定量检测。封装后,由于Au NCs具有AIE特性,所以Au NCs@ZIF-8的荧光强度明显增强。ZIF-8是一种多孔材料,加入Fe^(3+)后,Fe^(3+)能够进入ZIF-8内部,导致Au NCs的荧光被Fe^(3+)猝灭,成功用于实际水样中Fe^(3+)的检测。尽管该实验步骤复杂并涉及新型纳米材料的合成和表征,但它成功地整合了无机化学、分析化学以及材料化学的相关知识,且操作难度适宜。这为提升学生的动手能力和科技前沿理解提供了一次宝贵的机会。

Ratiometric Fluorescence Detection of 6-Mercaptopurine Based on the Nanohybrid of Fluorescence Carbon Dots and Gold Nanoclusters

The development of a simple and accurate quantitative method for the determination of 6-mercaptopurine (6-MP) is of great importance because of its serious side effects. Ratiometric fluorescence (RF) sensors are not subject to interference from environmental factors, and exhibit enhanced precision and accuracy. Therefore, a novel RF sensor for the selective detection of 6-MP was developed. The present work reports a sensitive and selective RF sensor for the detection of 6-mercaptopurine, by hybridizing carbon nanodots (CDots) and gold nanoclusters (AuNCs) capped with bovine serum albumin (BSA). The CDots serve as the reference signal and the AuNCs as the reporter. On addition of the 6-MP, AuNCs formed aggregates, because the existing cross-links within the AuNCs and BSA structure were broken in favour of the Au-S bonds, which can enhance the fluorescence of AuNCs, while the fluorescence of CDots is stable against 6-MP, leading to distinct ratiometric fluorescence changes when exposed to 6-MP. 6-MP could be detected in the range of 0 - 30.22 μM with a detection limit of 54 nM. The developed sensor was applied for the determination of 6-MP in human serum samples and satisfactory results were obtained.

利用AuNCs@GSH-CAP体系荧光增强检测BSA的研究

蛋白质的研究是当下的热点,目前已经涉及到了生物、医学、食品等各个领域,而纳米技术的发展极大程度上促进了对蛋白质的研究.简便、高灵敏、高选择性的检测方法是实现重大疾病早期诊断和治疗的关键,也是目前市场潜力巨大的方向.但是许多检测方法的荧光探针合成较为复杂以及成本高,且需要使用有毒性的有机试剂.采用氯霉素(CAP)荧光猝灭的金纳米簇(AuNCs@GSH)体系作为探针,通过体系荧光增强效应来检测牛血清白蛋白(BSA).BSA可以增强AuNCs@GSH-CAP体系荧光强度,在一定浓度范围内体系荧光增强与BSA的浓度呈正相关.该方法具有较好的选择性和抗干扰性,且荧光效果明显,实现了在10~160μmol/L内具有良好的线性关系,其检测限为0.1μmol/L,对于蛋白质的快速检测有良好的发展前景.

Gold Nanoclusters Templated by Poly-cytosine DNA as Fluorescent Probes for Selective and Sensitive Detection of Thiocyanate

Gold nanoclusters(AuNCs) were prepared in the presence of the nucleobases of poly-cytosine DNAs in this paper. We have demonstrated tliat the fluorescence of the AuNCs is quenched by thiocyanate(SCN^-) through the interaction between SCN^- and gold atoms. AuNCs can receive energy from nucleobases to boost their emission intensity, while in the presence of SCN^-, they coordinate with Au atoms and influence the energy transfer between the nucleobases and AuNCs, leading to the fluorescence quenching. The decreased fluorescence intensity was in proportion to the concentration of SCN^- in the range of 8.0×10^-7-1.5×10^-5 mol/L with a limit of detection of 4.2×10^-7 mol/L(3σ). We further validated the practice of this probe througli the detection of SCbT in natural water samples.

Microwave-assisted in situ synthesis of fluorescent gold nanoclusters with BSA/montmorillonite and application on latent fingermark imaging

A method for in situ preparation of fluorescent gold nanoclusters(Au NCs) with bovine serum albumin/montmorillonite composite powder(Au NC-BSA/MMT) was developed, and the products were used to detect latent fingermarks. In this work, Au NCs were "grown" both inside and on the surface of BSA/MMT clay using one-step reduction of HAu Cl4 by BSA. The as-prepared Au NC-BSA/MMT nanocomposites emit intensive red fluorescence under the excitation of UV-visible light and show stable chemical features and low toxicity. The obtained fluorescent powders were characterized by UV-visible absorption spectroscopy,fluorescence spectroscopy, infrared spectroscopy, transmission electron microscopy/high-resolution transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction to depict their sizes, structural information and optical features. Given their environmentally friendly preparation, simple operation, low cost, efficient UVvisible radiation-dependent photoluminescence and good affinity with finger residues, the in situ synthesized Au NC-BSA/MMT nanocomposite powders were used as an alternative fluorescent developing reagent for developing latent fingermarks deposited on various object surfaces(such as glass, aluminum foil, painted metal, plastic products and weighing papers) for individual identification. As results, the developed fingermarks with clear patterns and satisfactory level-2(minutiae points) and level-3(sweat pores) ridge details were obtained. Notably, treated prints could be excited by red light and emitted near infrared fluorescence, which was beneficial to avoid background interference and reduce the damage caused by UV light. With the advantages of the simple preparation process and good enhancement performance for latent fingermarks, the proposed method might be used in the preparation of various fluorescent probes for detecting trace evidence in forensic sciences.

Emerging NIR-Ⅱ Luminescent Gold Nanoclusters for In Vivo Bioimaging

Gold nanoclusters(AuNCs)with near-infraredⅡ(NIR-Ⅱ)photoluminescence(PL)have emerged as novel bioimaging probes for in vivo disease diagnosis.So far,it still lacks a systematic review focusing on the synthesis,PL tuning,and in vivo imaging of NIR-Ⅱluminescent AuNCs.In this review,we briefly introduce the synthesis of NIR-Ⅱluminescent AuNCs using various surface ligands.We discuss the origins and properties of NIR-ⅡPL in AuNCs,and summarize the strategies for improving and/or tuning NIR-ⅡPL emissions.We also provide an overview of the recent progress in the application of AuNCs in tumor-targeted imaging,molecular imaging,and other areas(such as the sensitive imaging of bones,vessels,lymph nodes,etc.).Finally,we present the prospects and challenges in the field of NIR-Ⅱluminescent AuNCs and related imaging applications,expecting to offer comprehensive understanding of this field,and thereby deepening and broadening the biological application of AuNCs.

金纳米团簇所发射荧光的稳定性及其表面的光催化氧化还原

金纳米团簇的荧光和光催化活性是其重要性质.本文合成了水溶性的卡托普利(Capt)和谷胱甘肽(GSH)覆盖的Au_(25)(Capt)_(18)和Au_(15)(GSH)_(13)纳米团簇,并研究了与其表面光氧化还原过程相关的荧光稳定性。发现Au_(25)(Capt)_(18)在氧气环境和近红外飞秒激光(810nm,300mW)照射下,出现了因表面氧化导致的双光子荧光效率衰减。而Au_(15)(GSH)_(13)的双光子荧光效率在相同的激发下保持稳定.两种金纳米团簇荧光稳定性不同的原因被归因于其不同的带隙,并使用光子能量高于两种金纳米团簇带隙的单光子激发证实了这一解释。通过添加不同试剂进行对比实验,对Au_(25)(Capt)_(18)表面金原子的光催化氧化还原活性进行了调控和理解.

Ratiometric fluorescence and visual sensing of ATP based on gold nanocluster-encapsulated metal-organic framework with a smartphone

Adenosine triphosphate(ATP)plays an important role in various biological processes and the ATP level is closely associated with many diseases.Herein,we designed a novel dual-emissive fluorescence nanoplatform for ATP sensing based on red emissive europium metal-organic framework(Eu-MOF)and blue emissive gold nanoclusters(AuNCs).The presence of ATP causes the decomposition of Eu-MOF owing to strong affinity of Eu3+with ATP.As a result,the red emission of Eu-MOF decreases while the blue emission of AuNCs remains unchanged.The distinct red/blue emission intensity change enables the establishment of a ratiometric fluorescent and visual sensor of ATP.Moreover,a fluorescent paper-based sensor was fabricated with the ratiometric ATP probes,which enabled easy-to-use and visual detection of ATP in serum samples with a smartphone.

基于CDs/AuNCs@ZIF-8的双发射比率荧光传感器快速检测铅离子

将碳点(CDs)和发光材料金纳米团簇(AuNCs)封装在沸石咪唑酸框架(ZIF-8)中,构建了CDs/AuNCs@ZIF-8双发射比率荧光传感器。表征了其形貌和光学性能,探讨了铅离子(Pb^(2+))对该比率探针的荧光猝灭机理。根据Pb^(2+)对比率探针的猝灭作用,利用该比率探针的荧光强度比值(F_(644)/F_(460))的变化定性定量检测Pb^(2+)。在最佳条件下,CDs/AuNCs@ZIF-8对Pb^(2+)的检测范围为9~140μmol/L,检出限为3.61μmol/L。将该双发射比率荧光传感器应用于实际水样的测定,加标回收率在93.0%~111.2%之间,相对标准偏差(RSD)小于7.0%。该方法能够用于实际样品中Pb^(2+)的检测。

基于聚A单链DNA模板合成金纳米簇快速检测化妆品中的氯霉素

以聚A单链DNA为模板合成的金纳米簇,构建了一种新的荧光生物传感方法用于检测化妆品中的氯霉素。结果表明,最优试验条件为:反应温度为25℃,反应时间为5 min,缓冲液pH值为5.5。该方法用于检测氯霉素残留的检测线性范围为0.01~80μmol/L,检出限为7.0 nmol/L。用该方法测定爽肤水、面膜、玻尿酸样品中氯霉素的含量,回收率为98.12%~108.40%,相对标准偏差为2.32%~8.82%。

Site-specific fabrication of gold nanocluster-based fluorescence photoswitch enabled by the dual roles of albumin proteins

Fluorescence photoswitch is becoming increasingly desirable for many applications,but its controllable fabrication still remains challenging yet.In this paper,a new strategy is proposed to fabricate fluorescence photoswitch by harnessing dual roles of albumin proteins as both photochrome carriers and biotemplates of fluorophore.As an example,we demonstrated the successful fabrication of a fluorescence photoswitch by incorporating both the photochromic diarylethene dye(CMTE)and red-emitting fluorescent gold nanoclusters(AuNCs)into the specific domains of bovine serum albumin(BSA)in a highly controllable manner.Detailed spectral and photophysical characterisation showed that CMTE well-retains the photochromic properties within the CMTE–BSA–AuNC construct,although its photoconversion rate is slightly retarded.Different from previously reported photoswitches,the fluorescence of the present system is mainly modulated via the inner filter effect(IFE)mechanism,which exhibits high switching efficiency with an on-off ratio up to 90%,reversible fluorescence response and good antifatigue performance.This work provides a new,generable albumin protein-assisted strategy of fabricating advanced fluorescence photoswitch,which can find wide applications in biological,optical and information fields.

基于对硝基苯酚荧光内滤效应的脂肪酶活性测定

基于金纳米簇的荧光特性和对硝基苯酚的荧光内滤效应检测脂肪酶活性。利用谷胱甘肽制备金纳米簇,作为反应体系的荧光团,棕榈酸对硝基苯酯在脂肪酶的作用下水解为对硝基苯酚,充当荧光吸收剂,基于荧光内滤机理测定脂肪酶活性,并对反应条件进行优化。结果显示:棕榈酸对硝基苯酯质量浓度1.6 mg/mL、pH 7.5、温度50℃、反应时间20 min时,相对荧光强度(F_(0)-F)与脂肪酶活性在5.6~196 U/L范围内呈正相关,线性方程为y=2.0035+0.9368x,相关系数r2为0.9978,检出限(信噪比为3)1.3 U/L。该方法操作简便,灵敏度高,可应用于脂肪酶活性的测定。

DNA模板荧光金属纳米团簇的合成及应用

荧光金属纳米团簇的尺寸介于金属原子和纳米颗粒之间,特殊的结构和尺寸赋予了金属纳米团簇一系列优异的荧光特性,如荧光强度高、抗光漂白性能强、较大的斯托克斯位移。脱氧核糖核酸(DNA)由于其独特的结构和可设计的序列而成为合成金属纳米簇的理想模板。DNA模板的金属纳米簇主要包括DNA模板的银纳米团簇(DNA-AgNCs)、铜纳米团簇(DNA-CuNCs)、金纳米团簇(DNA-AuNCs)等。DNA模板的金属纳米团簇作为一种新型的荧光纳米探针在生物传感和生物成像等领域具有较大潜在应用价值。基于先前对DNA模板的金属纳米团簇的研究,系统总结了DNA模板的金属纳米簇的制备、性质和在生物传感以及生物成像中的应用。最后,讨论了DNA模板的金属纳米簇的未来发展研究重点和前景。

金纳米簇的制备及其盐酸小檗碱检测应用

以谷胱甘肽为还原剂和稳定剂、氯金酸为金源,合成了谷胱甘肽-金纳米簇(GSH-Au NCs)。基于盐酸小檗碱对GSH-Au NCs的荧光猝灭作用建立了一种盐酸小檗碱荧光检测新方法。对体系pH值、缓冲类型、反应时间等实验条件进行了优化,在优化的实验条件下,方法的线性范围为2.44~24.4μmol·L^(-1),检出限为0.16μmol·L^(-1)。方法可用于盐酸小檗碱片剂中盐酸小檗碱含量的测定,且结果可靠。

荧光金纳米簇的制备及对水杨醛的高灵敏检测

开发了一种新型荧光传感器,即利用甲硫氨酸(Met)作为保护剂和还原剂,微波辅助快速合成了具有橙色荧光的金纳米簇(Met-AuNCs),用于检测水杨醛(SA)。在检测中,SA的醛基和AuNCs上的氨基发生亲核加成,形成席夫碱,与此同时Met的表面状态被改变,使AuNCs失去氨基酸配体的保护发生聚集。随着SA浓度的增加,AuNCs的特征荧光峰消失,而席夫碱的荧光强度逐渐增强,荧光由橙色变为绿色。用于SA检测的荧光传感器具有简单、快速、肉眼检测、高灵敏度等优点。该方法检测SA的线性范围为0.1~9.4μmol/L,检测限(LOD)低至7.4nmol/L。

大豆蛋白金纳米簇“关—开”型荧光探针检测炭疽杆菌生物标志物DPA

炭疽杆菌是高致病性病原微生物,引起的炭疽病在我国属于乙类传染病,因此建立操作简便、灵敏准确的炭疽杆菌检测方法对预防和控制炭疽传播,维护公共卫生安全至关重要。该研究创新性地提出以绿色材料大豆蛋白为保护剂和还原剂,采用微波加热法合成了一种具有强烈红色荧光发射的大豆蛋白金纳米簇(SPI-AuNCs)。采用TEM、 UV-Vis、 FL、 XPS、 FTIR等方法表征了SPI-AuNCs的成功合成和部分特殊性能。结果表明SPI-AuNCs呈球形,粒径大小在1.8~3.2 nm范围内,平均粒径为2.65 nm,在500~550 nm范围内未出现表面等离子体共振峰;SPI-AuNCs的最大激发波长为370 nm,最大发射波长为680 nm。SPI-AuNCs的表面官能团主要有—NH、—COOH、—OH、—SH等官能团,元素的组成主要包括C、 N、 O、 S、 Au元素。根据Cu^(2+)与SPI-AuNCs表面基团通过配位作用形成非荧光复合物,使荧光猝灭;而2,6-吡啶二羧酸(DPA)与Cu^(2+)具有更高的亲和力,可将Cu^(2+)从SPI-AuNCs表面竞争下来,使荧光恢复,据此建立了一种荧光“关-开”策略检测DPA的新方法。在最佳实验条件下,荧光恢复率(ΔF/F_(1))与DPA的浓度在1.15~70.0μmol·L^(-1)范围内呈良好的线性关系,线性方程为ΔF/F_(1)=0.011c+0.131,相关系数r=0.991,方法检出限为0.34μmol·L^(-1)。同时,通过加标回收实验研究了湖水和牛奶样品中DPA,得到加标回收率在97.3%~103.6%,表明了该方法在环境和食品样本DPA的检测中具有很大的应用潜力,可以为环境监测和食品安全提供方法学支持。

Green synthesis of gold nanoclusters using papayajuice for detection of L-lysine

Gold nanoclusters were rapid synthesized within 3 min at 120 ℃ by using papaya juice as a capping and reducing agent(P-AuNCs). The properties of the fluorescent probe were characterized by fluorescent spectroscopy, UV-vis spectroscopy, dynamic light scattering and transmission electron microscope.Based on the surface electron density increase-induced fluorescence enhancing principle, a high selective method for detection of L-lysine was developed with the as-prepared P-AuNCs coupling the fluorescence emission at 440 nm. The fluorescent probe showed high stability and good biocompatibility. Its fluorescence intensity was found to be linearly dependent on the L-lysine concentration in the range of 10.0μmol/L to 1000.0 μmol/L(R^2=0.969) with a limit of detection of 6.0μmol/L. Furthermore, the PAuNCs based approach was applied for monitoring the urine L-lysine contents, demonstrating great potential of fluorescent probes in real samples analysis.

基于金纳米簇和碳量子点的比率荧光传感法快速检测Hg^(2+)

汞离子(Hg^(2+))是一种致癌和无法生物降解的高毒重金属污染物,因此开发Hg^(2+)的快速检测方法对环境监测和人类健康维护具有重要意义。本研究成功构建了对Hg^(2+)快速裸眼筛查和检测的比率荧光传感器。首先采用水热合成法制备了发红色荧光的金纳米簇(Gold nanoclusters,AuNCs),采用微波辅助法制备了具有高量子产率(85%)且发蓝色荧光的碳量子点(Carbon quantum dots,CDs),然后将AuNCs和CDs简单混合,构建了具有单一激发和双发射的AuNCs-CDs比率荧光传感器。基于Hg^(2+)和Au~+的高亲和嗜金属效应,Hg^(2+)可明显猝灭AuNCs-CDs中AuNCs在670 nm处的荧光发射峰,而CDs在420 nm处的参比荧光强度基本保持不变。AuNCs-CDs的比率荧光信号(I_(670)/I_(420))与在0.005~1 mg·L^(-1)范围内的Hg^(2+)浓度呈良好的线性关系,检出限为1.5μg·L^(-1)。与此同时,随着Hg^(2+)浓度的增加,AuNCs-CDs在紫外灯下的发光颜色可用裸眼明显分辨(由粉红色变为蓝色)。该方法不仅对其他金属离子具有抗干扰性,而且在河水、大米以及白菜实际样品检测中也具有可行性,加标回收率为84.5%~105.1%。因此,利用AuNCs-CDs可构建一种理想的比率荧光传感器,其可用于Hg^(2+)的快速灵敏检测,并有望真正应用到食品安全和环境检测中。

基于牛血清白蛋白修饰的金纳米簇的荧光光谱法快速测定维生素B_(12)药片中Co^(2+)的含量

采用化学还原法合成牛血清白蛋白(BSA)修饰的金纳米簇(AuNCs),基于Co^(2+)对AuNCs的荧光猝灭作用,提出了一种快速、简便、灵敏测定Co^(2+)含量的方法。以柠檬酸为还原剂、BSA为保护剂、氯金酸为原料合成AuNCs。分取0.20 mL AuNCs溶液,加入0.6 mL pH 9.0碳酸钠-碳酸氢钠缓冲溶液,用水稀释至1.00 mL,在发射波长630 nm处测量上述体系(空白体系)的荧光强度F0。取10片维生素B12药片,研磨后,分取0.1270 g,用水溶解并稀释至100 mL,分取10μL于空白体系中,混匀后静置反应5 min,测量荧光强度F,利用荧光强度的差值ΔF(ΔF=F0-F)进行定量。结果显示:合成的AuNCs分布均匀,Co^(2+)对AuNCs体系有荧光猝灭作用,属于动态猝灭过程。添加10倍Co^(2+)浓度的干扰离子,Fe^(2+)、Pb^(2+)、Al^(3+)、Zn^(2+)、Mg^(2+)、Cr^(3+)、Cu^(2+)、Sr^(2+)、Mn^(2+)、Ca^(2+)不产生干扰,Fe3+、Ni2+的干扰可通过添加三乙醇胺和邻二氮菲掩蔽,Hg2+的干扰严重。Co^(2+)浓度分别在2.0×10^(-11)~1.5×10^(-10)mol·L^(-1)和1.5×10^(-10)~9.9×10^(-10)mol·L^(-1)内与对应的ΔF呈线性关系,检出限(3s/k)为1.7×10^(-12)mol·L^(-1)。按照标准加入法对两个厂家的实际样品进行回收试验,所得测定值和标签值较为接近,Co^(2+)回收率均接近100%,测定值的相对标准偏差(n=5)均小于5.0%。

基于金纳米团簇/氧化石墨烯的高灵敏复合荧光纳米传感器检测水产品中重金属汞离子

目的基于金纳米团簇(aptamer@gold nanoclusters,Apt@AuNCs)/氧化石墨烯(graphene oxide,GO)的高灵敏复合荧光纳米传感器建立检测水产品中汞离子(Hg^(2+))的方法。方法以寡核苷酸序列为模板通过一步法快速合成具有直接特异性识别Hg^(2+)能力的Apt@AuNCs;Apt@AuNCs作为荧光能量供体,与GO纳米片结合,形成Apt@AuNCs/GO复合荧光纳米体系,此时,Apt@AuNCs荧光被GO猝灭;Hg^(2+)以T-Hg^(2+)-T结构与Apt@AuNCs结合,使得Apt@AuNCs脱离GO表面,体系荧光得到恢复,从而实现Hg^(2+)的快速荧光法检测。结果最佳检测条件为:选择适配体序列为CCCCCCCCCCCCTTCTTTCTTCCCCTTGTTTGTT、GO质量浓度为0.30 mg/mL、激发波长为345 nm、GO与Apt@Au NCs孵育时间为35 min。该方法的Hg^(2+)检出限为0.189 nmol/L,定量限为0.630 nmol/L,线性范围为0.5~10.0 nmol/L。选择小龙虾和鲢鱼作为实际检测样品,通过标准加入法进行测试,其加标回收率为87.18%~109.90%。结论该复合荧光纳米体系无需复杂预处理,实现了对实际样品中Hg^(2+)的现场、简单快速且高灵敏的测定,为水产品中Hg^(2+)的检测提供了一种新思路。