基于氧化碳球的上转换荧光传感新方法检测银离子

本文构建了以上转换纳米粒子(Upconversion Phosphors,UCPs)为供体,氧化碳球为受体的荧光共振能量转移新体系用于Ag+的检测。氧化碳球对上转换荧光供体的发射具有良好的猝灭效果,当氧化碳球的浓度达到0.038mg/mL时,猝灭效率最大,达到78%。向该体系中加入Ag+后,在浓度为1～100nmol/L范围内,UCPs的荧光恢复程度与Ag+的浓度呈线性关系。该方法测定Ag+的检出限为0.98nmol/L。本实验首次尝试构建以氧化碳球为受体的荧光共振能量转移(FRET)传感器来检测Ag+,结合了UCPs的上转换发光特性和氧化碳球优良的猝灭能力以及良好的分散性,为Ag+的检测提供了一个新的方法。     

基于上转换荧光纳米颗粒-聚多巴胺纳米颗粒的生物传感器检测癌胚抗原

以上转换荧光纳米颗粒(Upconversion nanoparticles,UCNPs)为能量供体,聚多巴胺纳米颗粒(Polydopamine nanoparticles,PDA NPs)为能量受体,构建基于荧光共振能量转移的传感平台检测肿瘤标志物癌胚抗原(Carcinoembryonic antigen,CEA)。相比于传统的均相结构UCNPs,此传感器中夹层结构UCNPs(Sandwich-structure UCNPs,SWUCNPs)具有更高的能量转移效率。将CEA适配体标记于SWUCNPs表面,当向溶液中加入PDA NPs,体系的荧光猝灭效率最高可达95%。加入CEA后,体系的荧光恢复,恢复程度与CEA浓度在1.0~250.0 ng/mL范围内呈良好的线性关系,检出限为0.86 ng/mL(S/N=3)。此传感体系具有较高的选择性,在缓冲溶液与血清样品中均显示出良好的重现性。本传感器采用的能量受体PDA NPs合成简单、无需标记、猝灭能力强、分散性良好,研究结果可为基于UCNPs的传感体系构建提供新的方法学模型。     

基于聚间苯二胺为受体的UC-FRET传感器检测凝血酶

本文以上转换发光材料(UCPs)为供体,聚间苯二胺(PMPD)为受体,构建了基于荧光共振能量转移(FRET)的传感平台,并将其用于凝血酶的检测。一定浓度的PMPD加入到标记单链DNA的UCPs体系中,对上转换发光的猝灭效率可以达到70%。当加入浓度在0.2~5.0nmol/L范围内的目标物凝血酶时,其荧光恢复程度与浓度呈线性关系,检出限为0.18nmol/L。PMPD因其良好的水溶性、荧光猝灭能力及免标记的特点为基于FRET技术的生物样品检测提供了新的平台。     

基于上转换荧光共振能量转移的ClO~-纳米探针

以"核-内壳-外壳"三层夹心结构上转换纳米材料(Sandwich Structure Upconversion Nanoparticles,SWUCNPs)为能量供体,异硫氰酸荧光素(FITC)为能量受体,构建了一种基于上转换荧光共振能量转移(UC-FRET)的纳米探针,其荧光猝灭效率高达95%。将该纳米探针用于水溶液中ClO~-的检测,ClO~-对配体的氧化使得能量供受体之间距离增大,上转换荧光恢复程度与ClO~-的浓度呈线性关系,线性范围为0.02~3.4mmol/L,检出限为0.008mmol/L。实验结果表明该纳米探针特异性强、灵敏度高、结构灵活。     

基于甲基红-CdTe量子点荧光共振能量转移体系测定痕量强力霉素

本文以甲基红(MR)为能量给体,CdTe量子点(QDs)为能量受体,构建了MRCdTe QDs荧光共振能量转移体系,同时基于荧光猝灭法建立了检测痕量强力霉素(DOX)的新方法。实验表明,在pH=8.0的Tris-HCl缓冲介质中,聚乙烯醇(PVA)胶束能缩短MR与CdTe QDs分子间的距离,二者之间发生有效能量转移,使CdTe QDs荧光强度增强。而强力霉素能够猝灭该体系中CdTe QDs的荧光强度,以此建立了能量转移荧光猝灭法测定痕量强力霉素的新方法。实验表明强力霉素的线性范围为8~350×10-9 mol/L,检出限为2.1×10-9 mol/L。方法可应用于实际样品中强力霉素残留的测定。     

CdTe/CdS-罗丹明荧光共振能量转移猝灭法测定铅(Ⅱ)及相互作用机制的研究

以巯基乙酸为修饰剂,水相合成量子产率高达75％的CdTe/CdS核壳型量子点,建立了以CdTe/CdS QDs作为能量供体,罗丹明B作为能量受体组成的荧光共振能量转移体系.在此基础上,以CdTe/CdS-罗丹明B为荧光探针,荧光共振能量转移猝灭为理论基础,设计出一种检测pb2+含量的方法.在0～9.62×10-11mo...     

氧化石墨烯/适配体-量子点荧光探针用于ATP检测

利用量子点标记技术,通过生物偶联方式,以无毒的InP/ZnS表面标记上ATP适配体(ABA-QD)为荧光团,氧化石墨烯(GO)为猝灭剂,二者组装成GO/ABA-QD纳米荧光探针,QD与GO之间产生长程共振能量转移(LrRET),量子点荧光猝灭。当ATP存在时,ATP适配体与其特异结合,构象改变,量子点从GO表面分离,二者之间的荧光共振能量转移被打断,量子点荧光恢复,通过荧光“开”方式检测ATP,检测ATP的检测限为40 nmol/L,线性范围为0.1～30μmol/L。该新型检测ATP的方法对肿瘤的发生、疾病的诊断以及活细胞原位成像等具有重要的意义。     

基于水溶性硅量子点的汞离子荧光传感器

本文基于Hg~(2+)对水溶性硅量子点(Si QDs)的荧光猝灭效应,构建了一种简单、快捷的Hg~(2+)荧光传感器。实验发现,当Si QDs表面的氨基与Hg~(2+)结合形成配合物时,Si QDs的荧光被猝灭,根据荧光猝灭程度与Hg~(2+)的浓度关系,可实现Hg~(2+)的检测。在优化的实验条件下,Si QDs的荧光猝灭程度与Hg~(2+)浓度在5.0×10-8~1.0×10-6 mol/L范围内呈良好的线性关系(R2=0.9978),检出限(3σ)为2.2×10-8 mol/L。在此基础上,借助Hg~(2+)易于与巯基结合形成稳定配合物的原理,选用治疗Hg~(2+)中毒的药品二巯基丙磺酸钠(DMPS)为模型,利用该巯基化合物可使Hg~(2+)猝灭Si QDs的荧光恢复的特性,建立了一种检测DMPS的新方法。     

基于荧光共振能量转移的金纳米粒子/碳量子点荧光纳米探针检测精氨酸

利用碳量子点(CQDs)和金纳米粒子(Au NPs)间的荧光共振能量转移(FRET)效应成功实现了精氨酸的快速检测。采用一步微波辅助法合成具有优良荧光性能的碳量子点(CQDs),并对Au NPs/CQDs复合材料进行相应表征,分析了其猝灭和检测机制。对Au NPs/CQDs的添加量、p H值和反应时间进行了优化。在优化条件下,将此荧光体系用于精氨酸含量的检测,结果表明,荧光强度和精氨酸浓度在0.1~10.0μmol/L范围内呈良好的线性关系(R~2=0.993),检出限为5.8 nmol/L。采用本方法测定了葡萄汁中精氨酸的含量,回收率为105.4%~110.8%,表明本方法可用于果汁中精氨酸的实际检测。     

基于CdS@ZnS量子点与罗丹明B能量转移荧光猝灭法检测牛奶中土霉素

在吐温40存在下的pH 7.6 PBS缓冲溶液中,核壳型量子点CdS@ZnS与染料罗丹明B(RhB)能够发生有效的荧光共振能量转移,使能量给体CdS@ZnS的荧光猝灭,能量受体RhB的荧光增强。当加入土霉素(OTC)后,发现体系中RhB的荧光发生猝灭,且体系荧光猝灭的程度与土霉素浓度在4×10-8~60×10-8mol/L范围内呈良好的线性关系,相关系数r为0.999 0,检出限为1.13×10-9mol/L,以此建立了利用CdS@ZnS-RhB能量转移荧光猝灭法测定土霉素的新方法。方法具有稳定性好、灵敏度高、选择性好等特点,应用于牛奶中土霉素含量的测定,回收率为97.5%~103.7%,相对标准偏差(n=6)不大于2.0%。     

Fabricating UCNPs-AuNPs Fluorescent Probe for Sensitive Sensing Thiamphenicol

Anovel fluorescent probe has been constructed based on fluorescence resonance energy transfer(FRET) between upconversion nanomaterials(UCNPs) NaYF₄:Yb,Er and gold nanoparticles(AuNPs). The fluorescent "off-on" switching was formed for the detection of thiamphenicol(TAP) in egg samples. The fluorescence of UCNPs can be quenched to a certain degree by AuNPs. After adding TAP, the AuNPs generated aggregation and the fluorescence of UCNPs was recovered. The synthesized amination UCNPs and AuNPs were characterized by Fourier transform infrared spectroscopy(FTIR), UV-Vis, X-ray diffraction(XRD), energy dispersive spectrometer(EDS), and transmission electron microscope(TEM) techniques for observation and confirmation. As a model target, the detection of TAP has two linear ranges in the buffer solution within 0.01-0.1 μmol/L and 0.1-1 μmol/L using this fluorescent probe. The detection limit was obtained to be 0.003 μmol/L(S/N=3), which is favorable for trace analysis. The recovery of TAP from 98.2% to 105.3% was obtained, and the relative standard deviation(RSD) was from 2.5% to 4.3%. Furthermore, the method established in this study based on the UCNPs auto-low background fluorescence has high selectivity and strong ability to eliminate interference, which is beneficial to analyzing complex samples.     

Upconversion nanoparticle-based fluorescence resonance energy transfer assay for Cr(III) ions in urine

A novel assay of chromium(III) ion based on upconversion fluorescence resonance energy transfer was designed and established. Lysine-capped NaYF₄:Yb/Er upconversion nanoparticles (UCNPs) and dimercaptosuccinic acid-capped gold nanoparticles (AuNPs) were used as the energy donor and acceptor, respectively. They were bound together via electrostatic interaction, resulting in the quenching of the fluorescence of UCNPs by AuNPs. Chromium(III) ions can specifically and strongly interact with dimercaptosuccinic acid that was modified on the surface of AuNPs, leading to the separation of AuNPs from UCNPs and the recovery of fluorescence of UCNPs. The fluorescence recovery of UCNPs showed a good linear response to Cr³⁺ concentration in the range of 2–500 nM with a detection limit of 0.8 nM. This method was further applied to determine the levels of Cr³⁺ in urine. Compared with other fluorescence methods, current method displayed very high sensitivity and signal-to-noise ratio because of the excitation of near-infrared that can eliminate autofluorescence, providing a promising examination of biological samples for the diagnostic purposes.     

鱼精蛋白-核酸适配体-金纳米技术快速检测牛奶中的卡那霉素

基于聚阳离子鱼精蛋白与带负电的核酸适配体以及金纳米粒子之间的静电作用,发展了一种生物纳米检测技术,用于卡那霉素的检测;优化了缓冲溶液中阳离子、鱼精蛋白以及核酸适配体浓度,结果表明在20 mmol/L Na~+、1 mmol/L Mg~(2+)、2 mg/L鱼精蛋白、100 nmol/L核酸适配体条件下,卡那霉素在5~5 000 nmol/L范围内与金纳米粒子的吸光度比值呈现良好的线性关系,相关系数(R2)为0.992 8,方法的检出限为0.53 nmol/L。在此实验条件下,检测了牛奶中卡那霉素的含量,回收率为96%~98%,相对标准偏差为1.5%~3.2%。该方法选择性高,灵敏度好,线性范围广,显示出其应用于食品中卡那霉素检测的优势。     

Aptamer‐Based Turn‐On Detection of Thrombin in Biological Fluids Based on Efficient Phosphorescence Energy Transfer from Mn‐Doped ZnS Quantum Dots to Carbon Nanodots

This paper presents the first example of a sensitive, selective, and stable phosphorescent sensor based on phosphorescence energy transfer (PET) for thrombin that functions through thrombin–aptamer recognition events. In this work, an efficient PET donor–acceptor pair using Mn‐doped ZnS quantum dots labeled with thrombin‐binding aptamers (TBA QDs) as donors, and carbon nanodots (CNDs) as acceptors has been constructed. Due to the π–π stacking interaction between aptamer and CNDs, the energy donor and acceptor are taken into close proximity, leading to the phosphorescence quenching of donors, TBA QDs. A maximum phosphorescence quenching efficiency as high as 95.9 % is acquired. With the introduction of thrombin to the “off state” of the TBA‐QDs‐CNDs system, the phosphorescence is “turned on” due to the formation of quadruplex‐thrombin complexes, which releases the energy acceptor CNDs from the energy donors. Based on the restored phosphorescence, an aptamer‐based turn‐on thrombin biosensor has been demonstrated by using the phosphorescence as a signal transduction method. The sensor displays a linear range of 0–40 nM for thrombin, with a detection limit as low as 0.013 nM in pure buffers. The proposed aptasensor has also been used to monitor thrombin in complex biological fluids, including serum and plasma, with satisfactory recovery ranging from 96.8 to 104.3 %. This is the first time that Mn‐doped ZnS quantum dots and CNDs have been employed as a donor–acceptor pair to construct PET‐based biosensors, which combines both the photophysical merits of phosphorescence QDs and the superquenching ability of CNDs and thus affords excellent analytical performance. We believe this proposed method could pave the way to a new design of biosensors using PET systems.     

A simple AuNPs-based colorimetric aptasensor for chlorpyrifos detection

In this work, a simple gold nanoparticles(Au NPs) based colorimetric biosensor was developed for chlorpyrifos(Chl) detection using an aptamer as the capture probe. The Chl-aptamer with low dissociation constant(Kd) of 58.59 ± 6.08 nmol/L was selected by ss DNA library immobilized systematic evolution of ligands by enrichment(SELEX). In the absence of Chl, the Chl-aptamer acted as the stabilizer for Au NPs in salt solution. In the presence of Chl, the highly specific Chl-aptamer bound with Chl ta...     

Gold nanoparticle-enzyme conjugates based FRET for highly sensitive determination of hydrogen peroxide, glucose and uric acid using tyramide reaction

In this paper, we report a new strategy for highly sensitive determination of hydrogen peroxide, glucose and uric acid based on fluorescence resonance energy transfer (FRET) using gold nanoparticles (AuNPs) as energy acceptors. The principle is based on highly sensitive reaction of tetramethyl rhodamine (TMR) labeled tyramide and hydrogen peroxide catalysed by horseradish peroxidase (HRP), and the fluorescence spectrum of TMR (EX(max) 575 nm) partially overlaps with the visible absorption bands of AuNPs. We demonstrated an efficient FRET between tyramide labeled TMR (as energy donors) and HRP (BSA) conjugated AuNPs (as energy acceptors) due to the formation of TMR-labeled HRP-AuNPs or TMR-labeled BSA-AuNPs in the presence of H(2)O(2). We observed that the quenching of the fluorescence signal depended linearly on the H(2)O(2) concentration within a range of concentrations from 25 to 400 nM and the detection limit of this assay was 10 nM. Based on the principle for determination of H(2)O(2), we developed a new strategy for assay of glucose and uric acid by coupling with glucose oxidase (GOx)-mediated and uricase-mediated reaction. The established methods were successfully used for determination of glucose and uric acid levels in human sera, and the results obtained are in good agreement with commercially available methods. Our methods are at least 1 order of magnitude more sensitive than the commercially available methods. More importantly, our method described here can be extended to other assay designs using different oxidase enzymes, energy donors and energy acceptors, such as fluorescent quantum dots, near-infrared (NIR)-to-visible upconversion nanoparticles and even other metallic nanoparticles.     

免标记比色核酸适配体传感器同步快速检测孔雀石绿和无色孔雀石绿

研究以双特异性核酸适配体A3作为传感探针、纳米金（AuNPs）为指示剂、NaCl溶液为聚集诱导剂,构建了一种新型的免标记AuNPs比色生物传感器,可实现水产品中孔雀石绿（MG）和无色孔雀石绿（LMG）的同步、快速、可视化检测。该方法的检测原理是核酸适配体A3对MG和LMG有双特异性识别能力,可作为MG和LMG理想的识别受体。它可通过静电作用吸附到AuNPs表面,保护AuNPs并抑制高盐溶液诱导的聚集,AuNPs溶液颜色不变,即为红色;当加入靶标MG或LMG后,该核酸适配体能够与靶标特异性结合,并从AuNPs表面上解离,AuNPs失去保护作用而在高盐溶液诱导下发生聚集,溶液颜色由红变蓝。根据颜色变化,可通过肉眼定性或通过光谱仪定量分析MG和LMG的残留量。该方法首先将50 μL的核酸适配体A3（终浓度150 nmol/L）与150 μL的AuNPs（终浓度1.25 nmol/L）混合,室温孵育6 min。随后加入50 μL待测液,室温孵育30 min。最后加入50 μL NaCl（终浓度150 mmol/L）,4 min后观察溶液颜色变化,并分别测定MG和LMG在520 nm和650 nm下的吸光度值。结果表明,在最佳反应条件下,该方法能够特异性检测MG和LMG,而对磺胺嘧啶（SDZ）和硝基呋喃妥因（NFT）无交叉反应;当MG、LMG的浓度为0~17.5 μmol/L时,吸光度比值与靶标浓度呈现良好的线性关系,相关系数（R ² ）分别为0.9938和0.9715。MG和LMG的检出限分别为6.93 nmol/L和6.38 nmol/L,加标回收率分别为88.60%~93.30%和101.80%~107.00%,相对标准偏差（RSD）分别为2.27%~3.55%和2.62%~3.75%。该方法操作简单,快速和灵敏,可为水产品中MG和LMG的同步快速检测提供一种新方法。     

A Simple and Sensitive Nanogold RRS/Abs Dimode Sensor for Trace As3+ Based on Aptamer Controlled Nitrogen Doped Carbon Dot Catalytic Amplification

Using citric acid (CA) and ethylenediamine (EDA) as precursors, stable nitrogen-doped carbon dots (CD) nanosols were prepared by microwave procedure and characterized in detail. It was found that CD_Ns catalyze ethanol (Et)-HAuCl₄ to generate gold nanoparticles (AuNPs), which have strong surface plasmon resonance, Rayleigh scattering, (RRS) and a surface plasmon resonance (SPR) absorption (Abs) effect at 370 nm and 575 nm, respectively. Compled the new catalytic amplification indicator reaction with the specific As³⁺ aptamer reaction, a new RRS/Abs dual-mode aptamer sensor for the assay of trace As³⁺ was developed, based on the RRS/Abs signals increasing linearly with As³⁺ increasing in the ranges of 5–250 nmol/L and 50−250 nmol/L, whose detection limits were 0.8 nmol/L and 3.4 nmol/L As³⁺, respectively. This analytical method has the advantages of high selectivity, simplicity, and rapidity, and it has been successfully applied to the detection of practical samples.     

Label-free detection of adenosine based on fluorescence resonance energy transfer between fluorescent silica nanoparticles and unmodified gold nanoparticles

A sensitive and convenient strategy was developed for label-free assay of adenosine. The strategy adapted the fluorescence resonance energy transfer property between Rhodamine B doped fluorescent silica nanoparticles (SiNPs) and gold nanoparticles (AuNPs) to generate signal. The different affinities of AuNPs toward the unfolded and folded aptamers were employed for the signal transfer in the system. In the presence of adenosine, the split aptamer fragments react with adenosine to form a structured complex. The folded aptamer cannot be adsorbed on the surface of AuNPs, which induces the aggregation of AuNPs under high ionic concentration conditions, and the aggregation of AuNPs leads to the decrease of the quenching ability. Therefore, the fluorescence intensity of Rhodamine B doped fluorescent SiNPs increased along with the concentration of adenosine. Because of the highly specific recognition ability of the aptamer toward adenosine and the strong quenching ability of AuNPs, the proposed strategy demonstrated good selectivity and high sensitivity for the detection of adenosine. Under the optimum conditions in the experiments, a linear range from 98 nM to 100 μM was obtained with a detection limit of 45 nM. As this strategy is convenient, practical and sensitive, it will provide a promising potential for label-free aptamer-based protein detection.     

野酸枣氮掺杂荧光碳量子点高灵敏检测Hg2+

以天然产物野酸枣和色氨酸为原料,通过水热法一步合成量子产率为16.9%的氮掺杂荧光碳量子点。该碳量子点具有良好的水溶性和耐光性,在高盐环境中也呈现出了较高的稳定性。应用荧光光谱、透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)对碳量子点进行了表征。此外,Hg^2+能够有效地猝灭碳量子点的荧光,猝灭机理为电子转移的动态猝灭。基于此,可将碳量子点作为荧光探针检测Hg^2+。方法对Hg^2+的检测范围为1~50 nmol/L,检出限为0.26 nmol/L,能够应用于实际水样中Hg2+含量的测定。