非标记型双底物检测核酸适配体传感器研究

采用电沉积法制备了铁氰化镍(NiHCF)氧化还原电化学探针, 以金纳米粒子(GNPs)为固定核酸适配体的载体构建了非标记型测定凝血酶(TB)和腺苷(AD)的核酸适配体传感器. 采用循环伏安法(CV)和SEM对NiHCF膜进行了表征; 利用电化学阻抗(EIS)对传感器的组装过程进行了监测; 用CV和差分脉冲伏安法(DPV)对该传感器的电化学行为进行了研究. 该传感器对凝血酶的检测在1.0 fg·mL^-1～1.0 μg·mL^-1范围内成良好的线性关系, 相关系数为0.997, 检测限为0.27 fg·mL^-1; 对腺苷的检测在1.0 fg·mL^-1～1.0 ng·mL^-1范围内成良好的线性关系, 相关系数为0.997, 检测限为0.36 fg/mL. 该传感器制备简单, 灵敏度高, 抗干扰能力强.     

基于铁氰化铜的非标记型核酸适配体传感器的构建及其对腺苷的检测

采用电化学沉积法在金电极表面制备了铁氰化铜(CuHCF)氧化还原电化学探针,通过CN~-(CuHCF)和金纳米粒子(GNPs)之间形成Au-CN键的强相互作用力,将GNPs组装到电极表面后,再通过Au-S键将巯基化的腺苷适配体组装到电极表面,构建了高灵敏检测腺苷的非标记型核酸适配体传感器。利用电化学阻抗对传感器的组装构建过程进行监测。用循环伏安法和差分脉冲法考察了该传感器的电化学行为,并探讨了支持电解质和扫速对传感器的影响。在最优实验条件下,该传感器对腺苷在100 fg/mL~50.0 ng/mL范围内呈良好的线性响应,相关系数为0.998,检出限为45.0 fg/mL。     

半胱氨酸封闭剂为电化学探针的非标记型核酸适配体传感器

采用半胱氨酸为封闭剂和氧化还原电化学探针,制备了一种新型的非标记型电化学核酸适配体传感器,并用于测定凝血酶。 利用电化学阻抗对传感器的组装过程进行了监测。 用循环伏安法和差分脉冲伏安法研究了该传感器的电化学行为。 探讨了凝血酶孵育时间、测试pH值对传感器响应的影响。 该传感器对凝血酶在10.0~10000 μg/L范围内呈良好的线性响应,检测限为2.47 μg/L。     

基于铁氰化镍的非标记型核酸适配体电化学传感器检测凝血酶

在玻碳电极（GCE）表面首先用增敏作用的多壁碳纳米管(MWCNTs)夹心于两层电沉积的铁氰化镍（NiHCF）氧化还原电化学探针之间,然后以金纳米粒子为固定核酸适配体的载体,构建了检测凝血酶的非标记型核酸适配体生物传感器。 利用扫描电子显微镜(SEM)对MWCNTs和NiHCF的形貌进行了表征。 利用电化学阻抗谱对传感器的组装过程进行了监测,用循环伏安法（CV）和差分脉冲伏安法（DPV）对传感器的电化学行为进行了研究。 以铁氰化镍为探针的传感器对凝血酶的检测在1.0 ng/L~1.0 mg/L范围内呈良好的线性关系,相关系数为0.998,检测限为0.2 ng/L(S/N=3)。     

石墨烯修饰电化学适配体传感器测定双酚A

构建了一种检测双酚A(BPA)的电化学适配体传感器。利用在线电化学方法将氧化石墨烯还原为石墨烯,通过石墨烯与单链DNA之间的相互作用,将BPA适配体单链DNA吸附固定在修饰电极上,制备了BPA电化学适配体传感器。以铁氰化钾-亚铁氰化钾平衡电对为电化学探针,利用电化学循环伏安法和差分脉冲伏安法对BPA传感器的性能进行了研究。结果表明,在最优化实验条件下,传感器对BPA的检测线性范围在1.0×10~(-15)~1.0×10~(-10)mol/L之间,检出限为3.3×10~(-16)mol/L(S/N=3)。     

基于水滑石-金纳米粒子的阻抗型核酸适配体传感器的研究

在玻碳电极表面用电化学沉积法一步合成钴铝水滑石-金纳米粒子(CoAl LDH-GNPs)复合纳米材料,以复合纳米材料作为核酸适配体(Apt)的固定化基质,建立了一种高灵敏的阻抗型适配体传感器.采用扫描电镜(SEM)和能量色散谱仪(EDS)对CoAl LDH-GNPs复合纳米材料进行了表征,对电极的组装过程采用循环伏安法和电化学阻抗进行表征,对传感器的性能采用电化学阻抗进行研究.复合纳米材料CoAl LDH-GNPs构筑的传感器对凝血酶(THR)具有良好的信号响应,线性相关系数R=0.995,检出限为0.3 ng/L(S/N=3),检测范围为1.0 ng/L～ 100 μg/L.     

聚硫堇为探针与固定化载体的适配体传感器用于双酚A的检测研究

研制了一种简单和灵敏地检测环境激素双酚A(BPA)的电化学适配体传感器。首先在玻碳电极(GCE)表面采用电沉积法沉积一层多孔纳米金(NP-Au),再采用电聚合法将硫堇(TH)和适配体(APT)一步聚合到电极表面,以聚硫堇(PTH)作为电化学探针和APT的固定化载体,以牛血清白蛋白(BSA)抑制非特异性吸附,构筑GCE/NP-Au/PTH+APT/BSA传感器。采用差分脉冲伏安法对该传感器的电化学性能进行探究,发现双酚A在10.0 fg/mL~1.0 ng/mL浓度范围内有较好的信号响应,检出限为5.3 fg/mL。以GCE/PTH+APT/BSA传感器作为对照,其对双酚A在10.0 fg/mL~1.0 ng/mL浓度范围内呈线性关系,检出限为9.0 fg/mL。结果表明多孔纳米金的引入可有效提高传感器的灵敏度。GCE/NP-Au/PTH+APT/BSA传感器具有选择性高和检出限低等优点。     

基于溴化银－银－碳纳米管复合物与核酸适配体的阴极光电化学传感器检测赭曲霉素A

该研究利用水热法制备了一种新的溴化银－银－碳纳米管（AgBr－Ag－CNTs）复合材料,并通过扫描电子显微镜、X-射线衍射和X-射线光电子能谱对其进行表征。以AgBr－Ag－CNTs作为光电阴极,相比于单一的AgBr和二元的AgBr－Ag复合材料,其具有更高的光电化学活性。采用K3［Fe（CN）6］作为光电子受体能进一步提高光电流信号。基于AgBr－Ag－CNTs为光电阴极传感基底,构建了一种灵敏检测赭曲霉素A （OTA）的核酸适配体传感器。对目标物的线性浓度范围为4.0 pg/mL ~ 2.5 ng/mL,相关系数（r2）为0.994,检出限为1.5 pg/mL。该传感器制备简单、成本低、灵敏度高、抗干扰强,对样品检测的回收率为92.0% ~ 108%,可用于实际样品中OTA的分析。     

磷掺杂ZIF-67衍生复合材料的免疫传感器检测人免疫球蛋白

以六水合硝酸钴(Co(NO3)2·6H2O)和2-甲基咪唑(C4H6N2)为原料,通过水热法合成了ZIF-67,进一步煅烧后制备磷掺杂的CoP@C,并对其形貌及物相进行表征。CoP@C与离子液体(IL)混合修饰碳糊电极(CPE)制备CoP@C/IL-CPE,并以戊二醛(GA)为交联剂,牛血清白蛋白(BSA)为封闭剂,构建BSA/免疫球蛋白抗体(anti-IgG)/GA/CoP@C/IL-CPE传感器。通过循环伏安法和电化学阻抗谱研究其电化学行为,并用差分脉冲伏安法对人免疫球蛋白进行定量检测。在最佳条件下,该传感器对免疫球蛋白检测的线性范围为0.01～1000 ng/mL,检出限为4 pg/mL。     

高灵敏赭曲霉毒素A电化学适配体传感器的构建

利用CdS QDs/SiO_2纳米粒子作为电子媒介体制备了一种高灵敏度的赭曲霉毒素A(OTA)电化学适配体传感器.实验过程中,首先合成了CdS QDs/SiO_2纳米粒子,之后采用透射电子显微镜、紫外吸收光谱方法等对制备的纳米材料进行了表征.该复合材料在保持了SiO_2纳米粒子良好的生物相容性和均一性的同时增加了CdS QDs的负载量,从而有利于传感器的信号放大.在组装过程中,先将捕获探针(cDNA)固定在金电极表面,适配体与捕获探针杂交形成双链,此时没有电化学信号;当OTA存在时,适配体会与OTA结合而从电极表面脱离,再将标记有CdS QDs/SiO_2纳米复合材料的信号探针(sDNA)与电极上自由的cDNA杂交,产生电化学信号.最优条件下,传感器电化学信号强度增加值与OTA浓度在0.5 pg/m L~10.0 ng/m L范围内呈现良好的线性关系,检测限低至0.091 pg/m L.     

非标记型血小板衍生生长因子核酸适体传感器

合成了介孔二氧化硅负载金纳米颗粒(Au-MSN), 通过壳聚糖(CHIT)将Au-MSN固定到裸玻碳电极表面, 采用自组装法将带巯基的血小板衍生生长因子(PDGF)核酸适体固定到Au-MSN修饰过的玻碳电极表面, 制得PDGF核酸适体传感器. 以亚甲基蓝作为电化学活性嵌入剂, 通过检测核酸适体与目标分析物PDGF特异性结合前后亚甲基蓝电信号的变化, 实现了对PDGF的定量检测. 考察了缓冲溶液的pH、 扫描速度及PDGF培育时间等条件对检测结果的影响. 结果表明, 在pH为7.6时, 该传感器的检测范围为0.1 pg/mL~1 μg/mL, 检出限为0.03 pg/mL. 该传感器制作简单、 成本低廉、 灵敏度高且稳定性好.     

基于Cu-TPA的电化学生物传感器对黄曲霉毒素B1的检测

利用对苯二甲酸铜(Cu-TPA)能产生强的电化学信号设计了一种灵敏的电化学生物传感器, 并将其用于测定黄曲霉毒素B1(AFB1). 信号探针中的Cu-TPA含有可产生电化学信号的Cu(Ⅱ), 当加入一定量的AFB1后, AFB1与探针中特定的适配体结合, 使信号探针脱落, 电化学信号降低. 根据电化学信号值的变化实现了对AFB1的检测. 在最佳条件下, 该传感器的检出限为4.2×10 ^-6 ng/mL(S/N=3), 线性范围为10 ^-5~10 ng/mL. 将该传感器用于啤酒中AFB1的检测, 回收率为95%~106%.     

Poly(allylamine hydrochloride) Functionalized Multiwalled Carbon Nanotube Modified Carbon Paste Electrode as Acetylcholinesterase Biosensor Transducer

In this work, a sensitive, practical and reliable acetylthiocholine (ATCh) biosensor based on poly(allylamine hydrochloride) functionalized multiwalled carbon nanotube (PAH/MWCNT) was fabricated and used for pesticide detection. As far as we know, this is the first work that constitutes the usage of PAH and MWCNT for ATCh biosensor. The developed system was characterized by using scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The influence of parameters such as enzyme amount and pH were examined and a linearity between 5×10^?5 M?2.0×10^?3 M for ATCh was obtained. The proposed biosensor was applied for a model pesticide, monocrotophos, detection. The analytical curve showed an excellent linearity in the monocrotophos concentration range of 1–25 pg/mL with an incubation time of 5 min. Limit of detection and limit of quantification values were calculated as 0.88 and 2.9 pg/mL, respectively. The system was also applied for detection of monocrotophos in grape, tomatoe, tap and mineralized water samples and promising recovery values were obtained.     

An Electrochemical Aptamer Biosensor for Bisphenol A on a Carbon Nanofibre-silver Nanoparticle Immobilisation Platform

A nanocomposite platform of silver nanoparticles and carbon nanofibres (AgCNFs) was used to immobilise a bisphenol A specific 63-mer ssDNA aptamer to form a biosensor. The fabrication process of the biosensor was studied with electrochemical impedance spectroscopy and cyclic voltammetry in the presence of [Fe(CN)₆]^3−/4− as redox probe. The biosensor detected bisphenol A in a linear range of 0.1–10 nM, with a limit of detection of 0.39 nM using square wave voltammetry (SWV). The biosensor exhibited good selectivity in the presence of interfering species at 100-fold concentrations and was used to detect BPA in real water sample.     

Electrochemical Determination of Aflatoxin B1 (AFB1) Using a Copper-Based Metal-Organic Framework (Cu-MOF) and Gold Nanoparticles (AuNPs) with Exonuclease III (Exo III) Assisted Recycling by Differential Pulse Voltammetry (DPV)

Abstract

A sensitive electrochemical biosensor was designed for determination of aflatoxin B1 (AFB1) using a copper-based metal-organic framework (Cu-MOF), which has strong electrochemical activity and exonuclease III (Exo III)-assisted recycling for dual signal amplification. Hairpin DNA (S1) was immobilized on the electrode. The AFB1 was recognized by aptamer DNA (S2) and complementary DNA (S3) was released. The S3 hybridized with the hairpin S1 to form the Exo III hydrolyzed double-stranded DNA, leaving a partial sequence of hairpin DNA (S1′) on the electrode and releasing S3 for the next cycle of the opening and digestion of hairpin S1. The amplified S1′ then was able to combine with more signal probes. Cu-MOF bond gold nanoparticles (AuNPs) by -NH₂ were immobilized to capture DNA (S4) to obtain Cu-MOF/AuNPs/S4. This signal probe Cu-MOF/AuNPs/S4 was able to hybridize with the electrode and generate an amplified electrochemical signal. Under the optimized conditions, this electrochemical biosensor for AFB1 exhibited a low detection limit of 6.7?×?10^?7?ng/mL at a signal-to-noise equal to 3 and a wide linear range from 10^?6 to 1?ng/mL. The biosensor was also used to analyze AFB1-spiked beer sample with recovery values between 96% and 103%. This method has the potential to become a valuable technology for detecting various toxins by the selection of the appropriate aptamer DNA.     

DNA Electrochemical Aptasensor for Detecting Fumonisins B1 Based on Graphene and Thionine Nanocomposite

In this paper, a novel aptasensor was designed by with the dual amplification of Au nanoparticles (AuNPs) and graphene/thionine nanocomposites (GS‐TH) for sensitive determination of fumonisins B₁ (FB₁). AuNPs is modified at the electrode surface to increase the electrical conductivity and fabricate specific recognition interface for FB₁ through the hybridization of capture DNA and its aptamer. Large number of TH molecules were loaded at the surface of graphene sheet to served as electrochemical probe and increase its electrochemical signal due to the excellent conductivity and large surface area of graphene sheet. This type of nanocomposites is then assembled to the single strand section of FB₁ aptamer at electrode surface by π–π stacking interactions between them, leading to an enhanced electrochemical signal. After the specific combination between FB₁ aptamer and its target (FB₁) in solution, GS–TH was released from electrode surface, resulting in a decreased electrochemical signal. The result demonstrated that the decreased currents were proportional to the FB₁ concentration in the range of 1–10⁶ pg/mL with a detection limit of 1 pg/mL. Besides, the developed aptasensor was also applied successfully for the determination of FB₁ in feed samples. The result shows this aptasensor has a higher sensitivity and selectivity.     

Ultrasensitive electrochemical immunosensor of carcinoembryonic antigen based on gold-label silver-stain signal amplification

A novel gold-label silver-stain electrochemical immunosensor based on polythionine-gold nanoparticles (PTh-Au NPs) modified glassy carbon electrode (GCE) as a platform and secondary antibody labeled Au NPs (Ab₂-Au NPs) as immumoprobe for carcinoembryonic antigen (CEA) detection. The sandwich-type biosensor adopted anodic stripping voltammetry to detect silver stripping signal when the Ab₂-Au NPs of the formed immunocomplexes were stained with silver.     

An intriguing electrochemical impedance aptasensor based on a porous organic framework supported silver nanoparticles for ultrasensitively detecting theophylline

Porous organic frameworks (POFs) are excellently stable porous materials, which can be employed as host platforms to support metal nanoparticles as functional composites for various applications. Herein, a novel POF is successfully prepared via Friedel-Crafts reaction. Silver nanoparticles (Ag NPs) are embedded in the prepared POF to generate an Ag@POF composite, which not only possesses high surface area, outstanding physicochemical stability and outstretched π-conjugation skeleton, but also exhibits preferable electrochemical stability and conductivity. This composite is able to immobilize a mass of aptamer strands to fabricate an intriguing electrochemical aptasensor. Electrochemical impedance spectroscopy (EIS) is a commonly used technology to analyze the electrochemical signal variation. The Ag@POF-based biosensor shows the excellent electrochemical detection behavior through analyzing EIS. For instance theophylline as a research mode, the Ag@POF based electrochemical aptasensor reveals ultra-sensitiveness, high selectivity, remarkable stability, good repeatability and simple operability even in various real samples. Notably, this aptasensor has the sensitive detection performance with the limit of detection of 0.191 pg/mL (1.06 pmol/L) in a wide concentration range of 5.0 × 10^-4 – 5.0 ng/mL (2.78 × 10^-3 – 27.8 nmol/L).