Label-free aptamer-based electrochemical impedance biosensor for 17β-estradiol

A novel aptamer-based label-free electrochemical impedance spectroscopy biosensor for 17β-estradiol has been fabricated. The aptamers were firstly immobilized on the gold electrode through Au-S interaction; the aptamer probe was then bound with the addition of 17β-estradiol to form the estradiol/aptamer complex on the electrode surface. This leads to a significantly larger interfacial electron transfer resistance than that without the addition of 17β-estradiol. The change in the resistance had a linear relationship with 17β-estradiol concentration in the range of 1.0 × 10(-8) to 1.0 × 10(-11) mol L(-1), with a detection limit of 2.0 × 10(-12) mol L(-1). The biosensor showed high selectivity to 17β-estradiol and good stability. The designed biosensor has been applied to detect 17β-estradiol in human urine with satisfactory results.     

基于多边形金纳米颗粒的非标记型可卡因适体传感器的研制

实验合成了多边形金纳米颗粒,通过壳聚糖(CHIT)将合成的多边形金纳米颗粒固定在玻碳电极表面,然后通过自组装技术将带巯基的捕获DNA探针固定在修饰有多边形金纳米颗粒的电极表面,利用杂交反应使可卡因适体与DNA捕获探针结合,制成非标记型可卡因适体传感器。以六氨合钌作为电化学指示剂,通过测量传感器与目标物可卡因结合前后电流变化情况对可卡因进行测定。考察了缓冲溶液的pH、可卡因培育时间、扫描速度等对测定的影响。结果表明,在pH为7.40时该传感器的检测范围为1.0×10-10～1.0×10-3 mol/L,检测限为3.0×10-11 mol/L。该传感器制作简单,响应好,抗干扰能力强。     

MoS_2中空纳米球的制备及在超灵敏microRNA电化学生物传感器中的应用

采用模板法制备了二硫化钼中空球纳米材料,利用扫描电子电子显微镜、X射线衍射仪和Raman光谱仪对材料的形貌和结构进行表征.将适配体固定在金纳米粒子和二硫化钼共同修饰的电极上构建了一种新型的微小核糖核酸(microRNA)电化学生物传感器,采用循环伏安、微分脉冲伏安和电化学阻抗等技术对构筑的传感器进行表征.结果表明,microRNA浓度在1.0×10~(-10)~1.0×10~(-16)mol/L范围内峰电流(I)与microRNA浓度的负对数(-lgc)呈良好的线性,目标miRNA的检出限为0.55×10~(-16)mol/L.构建出的传感器具备选择性好、灵敏度高、稳定性强等特性,具有广阔的应用前景.     

新型"三明治"结构DNA电化学传感器对急性早幼粒细胞白血病相关融合基因的检测

基于急性早幼粒细胞白血病(APL)中PML/RARα融合基因的碱基序列,设计了新型的锁核酸(LNA)修饰寡核苷酸作为捕获探针和信号探针,研究出一种基于"三明治"传感模式的电化学生物传感器对PML/RARα融合相关基因进行检测.靶序列分别与捕获探针和信号探针杂交后形成"三明治"结构.将修饰电极置于含有底物3,3′,5,5′-四甲基联苯胺(TMB)和过氧化氢的测定溶液中,用计时电流法检测靶序列.结果表明,该传感器可定量识别和检测溶液中人工合成的短链APL PML/RARα融合基因片段.经过条件优化,杂交前后电流值与靶标链浓度在1.0×10~(-12) ～2.5×10~(-11) mol/L范围内呈良好的线性关系,检出限为8.5×10~(-13) mol/L.该方法简单、特异性好,有望用于实际样品的检测.     

氧化石墨烯修饰碳离子液体电极同时测定鸟嘌呤和腺嘌呤

以离子液体1-丁基-3-甲基咪唑六氟磷酸盐为粘合剂制备了碳糊电极,然后将氧化石墨烯滴涂到碳糊电极表面制成了一种新型的氧化石墨烯修饰碳离子液体电极。研究了鸟嘌呤和腺嘌呤在修饰电极上的电化学行为。实验结果表明,在0.1 mol/L醋酸盐缓冲溶液中(pH4.5),鸟嘌呤和腺嘌呤在该修饰电极上具有良好的电化学行为,在2.0×10-7～1.5×10-5mol/L浓度范围内鸟嘌呤和腺嘌呤的浓度在该电极上与电化学响应信号呈良好的线性关系,相关系数分别为为0.992和0.996。信噪比为3时,检出限为1.0×10-8mol/L。     

壳聚糖/Nafion膜固定氯化血红素制备过氧化氢生物传感器

以壳聚糖/Nafion复合膜为载体在玻碳电极上固定氯化血红素制备过氧化氢生物传感器。研究了血红素电极制备过程中的影响因素及其电化学性质,在1.0 mol/L pH 9.8的NH3-NH4Cl缓冲溶液中,血红素电极对H2O2的催化还原峰电流与H2O2浓度在7.5×10-5~1.45×10-3mol/L范围内成良好的线性关系,检测灵敏度为35.28μA/mM,检测限为3.5×10-5mol/L(S/N=3),同时研究了血红素电极的重现性、稳定性和选择性。     

基于Ru(bpy)2+3/AuNPs/SWCNTs/腺苷适配体电化学发光生物传感器用于腺苷的检测

利用AuNPs/Nafion复合膜技术固定Ru(bpy)2+3,采用羧基化碳纳米管固定氨基化腺苷适配体,制备腺甘电化学发光生物传感器.采用循环伏安法和电化学发光法对传感器进行表征.结果表明,此传感器具有良好的稳定性和重现性.腺苷与传感器作用后,腺苷与其适配体形成G四面体结构,Ru(bpy)2+3的电化学发光强度降低.在最佳实验条件下,电化学发光强度降低量与腺苷浓度的负对数在1.0×10-11~1.0×10-7 mol/L范围内呈良好的线性关系,线性方程为ΔIECL=-890lgC-5050,检出限(S/N=3)为5.0 × 10-12 mol/L.对1.0 × 10-10 mol/L腺苷平行测定11次,相对标准偏差为2.7%.用于尿液中腺苷的测定,加标回收率在 97.1%~110.0%之间.     

基于直立碳纳米管大面积金粒子的DNA生物传感器用于早幼粒白血病/维甲酸受体α融合基因检测

基于直立碳纳米管上的大面积金粒子构建了新型的电化学DNA生物传感器,用于急性早幼粒细胞白血病PML/RARα融合基因的检测。首先在直立碳纳米管电极表面溅射金粒子,采用自组装方法将巯基修饰的单链DNA固定到电极上,将氨基修饰的单链DNA和羧基化的CdTe量子点通过酰胺缩合反应生成CdTe修饰的DNA探针,通过与目标DNA的双杂交反应形成三明治结构,利用差分脉冲阳极溶出伏安法检测电极表面捕获的CdTe量子点,从而对DNA进行定量分析。结果表明,电极上Cd2+峰电流与目标DNA浓度(1.0×10-12~1.0×10-8 mol/L)的对数值呈线性关系,线性方程为ipa(μA)=1.626+0.132lgC(mol/L)(R=0.996),检出限为4.0×10-13 mol/L(3σ)。传感器表现出良好的重现性和稳定性。     

纳米金/石墨烯修饰电极的制备及其对多巴胺的测定

利用电化学还原方法制备纳米金/石墨烯修饰玻碳电极,研究了多巴胺(DA)在该修饰电极上的电化学行为,建立了电化学测定多巴胺的新方法。结果表明,在磷酸盐缓冲溶液中,此修饰电极对多巴胺的电化学响应具有很好的催化作用。利用差示脉冲伏安技术对多巴胺的电化学氧化进行定量分析,多巴胺的氧化峰电流与其浓度在1.0×10-7～1.0×10-5mol/L范围内呈良好的线性关系,检测限低至4.0×10-8mol/L。该修饰电极适于多巴胺的分析检测。     

量子点双标记的Fe3O4@Au磁性纳米DNA电致发光型传感器

合成了Fe3O4@Au磁性纳米粒子,并根据单链寡聚核苷酸(ss-DNA)杂交原理,利用量子点电化学发光,构建了DNA电化学传感器.在磁控玻碳电极(MCGCE)表面,将5′-SH-ssDNA捕获探针自组装在Fe3O4@Au磁性纳米粒子上,然后与目标DNA互补的一端杂交形成dsDNA,再与双标记了量子点的5′-NH2-ssDNA-NH2-3′信号探针杂交形成三明治杂交的DNA.应用循环伏安法对DNA的固定与杂交进行了表征.目标DNA浓度在1.0×10-13～1.0×10-11 mol/L范围与其响应的ECL信号呈线性关系,检出限为1.8×10-14mol/L.由于采用量子点双标记法,检测的灵敏度显著提高.     

以天青Ⅰ为介体的纳米金颗粒增强的葡萄糖传感器

采用层层自组装的方法和异种电荷互相吸引的原理,将Nafion修饰在金电极上固载带正电荷的天青Ⅰ,并利用天青Ⅰ中的氨基固载纳米金,再通过纳米金将酶固定在金电极表面,制成了葡萄糖传感器.采用循环伏安法和交流阻抗法,研究了金电极表面组装各层之后的电化学特征,以及电极对葡萄糖的电化学催化作用. 结果表明,天青Ⅰ不仅可以固定酶和纳米金,而且还可以在酶和电极之间有效地传递电子.在优化的实验条件下,该传感器对葡萄糖响应的线性范围为5.1×10-6 ~4.0×10-3 mol/L,检出限(S/N=3)为1.0 μmol/L.该生物传感器显示出较好的稳定性和抗干扰能力,将其用于人体血清中葡萄糖的测定,结果令人满意.     

氧化石墨烯/铁氰化铈修饰玻碳电极同时测定扑热息痛和咖啡因

采用滴涂法和电沉积法制备了氧化石墨烯/铁氰化铈(CeFe(CN)6)纳米复合膜修饰玻碳电极。用扫描电镜对氧化石墨烯和氧化石墨烯/CeFe(CN)6纳米复合膜进行了表征。分别用循环伏安法和差分脉冲伏安法研究了扑热息痛和咖啡因在修饰电极上的电化学行为。结果表明,在0.1 mol/L醋酸盐缓冲溶液(pH5.0)中,扑热息痛和咖啡因在此修饰电极上具有良好的电化学行为,扑热息痛和咖啡因分别在1.0×10-7～6.0×10-5mol/L和1.0×10-6～1.3×10-4mol/L浓度范围内与电化学响应信号呈良好的线性关系,相关系数分别为0.990和0.992;信噪比为3时,扑热息痛和咖啡因检出限分别为5.0×10-8mol/L和5.2×10-7mol/L。将本方法用于人尿样品分析,回收率为96.1%～105.4%。     

基于适体生物传感器的碱性磷酸酯酶化学发光检测腺苷

制备了一种可用于腺苷检测的适体生物传感器,以羧基磁性微球为载体,在其表面组装腺苷适体与地高辛修饰之腺苷适体互补的核酸短链,先加入一定浓度的腺苷,再连接抗地高辛的碱性磷酸酯酶,用化学发光法检测发光值,根据腺苷加入前后化学发光强度的变化来定量检测腺苷。实验考察了羧基磁性微球用量、氨基修饰的腺苷适体用量、地高辛修饰的核酸短链用量及抗地高辛的碱性磷酸酯酶用量对体系组装和腺苷识别的影响。结果显示,优化条件下,在1.0×10~(-7)~1.0×10~(-3)mol/L范围内,腺苷浓度的对数与发光信号呈线性关系(r~2=0.976 9),定量下限为1.0×10~(-7)mol/L。与其他核苷相比,腺苷的选择特异性更好,且在稀释血清中适体对腺苷有很好的特异性识别能力。     

Determination of radon using solid state nuclear tracks wireless sensing method

A highly sensitive and selective electrochemiluminescent (ECL) biosensor for the determination of adenosine was developed. Single DNA (capture DNA) was immobilized on the gold electrode through Au-thiol interaction at first. Another DNA modified with tris(2,2'-bipyridyl) ruthenium(II)-doped silica nanoparticles (Ru-SNPs) that contained adenosine aptamer was then modified on the electrode surface through hybridizing with the capture DNA. In the presence of adenosine, adenosine-aptamer complex is produced rather than aptamer-DNA duplex, resulting with the dissociation of Ru-SNPs-labeled aptamer from the electrode surface and the decrease in the ECL intensity. The decrease of ECL intensity has a direct relationship with the logarithm of adenosine concentration in the range of 1.0×10(-10) to 5.0×10(-6)molL(-1). The detection limit of the proposed method is 3.0×10(-11)molL(-1). The existence of guanosine, cytidine and uridine has little interference with adenosine detection, demonstrating that the developed biosensor owns a high selectivity to adenosine. In addition, the developed biosensor also demonstrates very good reusability, as after being reused for 30 times, its ECL signal still keeps 91% of its original state.     

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized on L-glutathione self-assembled monolayers

A novel hydrogen peroxide biosensor has been fabricated based on covalently linked horseradish peroxidase （HRP） onto L- glutathione self-assembled monolayers （SAMs）. The SAMs-based electrode was characterized by electrochemical methods, and direct electrochemistry of HRP can be achieved with formal potential of-0.242 V （vs. saturated Ag/AgCl） in pH 7 phosphate buffer solution （PBS）, the redox peak current is linear to scan rate and rate constant can be calculated to be 0.042 s^-1. The HRP-SAMs- based biosensors show its better electrocatalysis to hydrogen peroxide in the concentration range of 1 × 10^-6 mol/L to 1.2 × 10^-3 mol/L with a detection limit of 4 × 10^-7 mol/L. The apparent Michealis-Menten constant is 3.12 mmol/L. The biosensor can effectively eliminate the interferences of dopamine, ascorbic acid, uric acid, catechol and p-acetaminophen.     

基于 G-四联体门控制效应的铅离子适配体传感器

将富鸟嘌呤(G)序列核酸适配体与门控制效应相结合,通过控制门的开关实现信号放大,构建了新型电化学生物传感器,用于铅离子(Pb2+)的高灵敏检测。首先将单-6-巯基-β-环糊精(6-SH-β-CD)自组装在金电极上,形成有序排列的分子自组装膜,且分子之间留有空隙,可作为探针通过的门结构。随后将发夹结构的富含 G 序列的核酸适配体修饰在环糊精次面端口,制得可特异性识别 Pb2+的电化学生物传感器。富 G 序列适配体结合 Pb2+后可折叠形成 G-四联体结构(G4-Pb2+),覆盖住电极表面的探针通道,产生关门效应,使探针氧化还原电流强度减小,进而形成门控制效应,利用该效应可进行 Pb2+的定量检测。门控制效应显著提高了信噪比和检测的灵敏度,在1×10-13~5×10-11 mol/ L 浓度范围内,Pb2+浓度的负对数与 DPV 响应电流呈良好的线性关系,检出限为3.6×10-14 mol/ L(DL=3δb / K)。传感器用于实际水样品中 Pb2+的测定,结果令人满意。     

Electrochemical deoxyribonucleic acid biosensor based on the self-assembly film with nanogold decorated on ionic liquid modified carbon paste electrode

An electrochemical DNA biosensor was fabricated by self-assembling probe single-stranded DNA (ssDNA) with a nanogold decorated on ionic liquid modified carbon paste electrode (IL-CPE). IL-CPE was fabricated using 1-butylpyridinium hexafluorophosphate as the binder and the gold nanoparticles were electrodeposited on the surface of IL-CPE (Au/IL-CPE). Then mercaptoacetic acid was self-assembled on the Au/IL-CPE to obtain a layer of modified film, and the ssDNA probe was further covalently-linked with mercaptoacetic acid by the formation of carboxylate ester with the help of N-(3-dimethylamino-propyl)-N'-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide. The hybridization reaction with the target ssDNA was monitored with methylene blue (MB) as the electrochemical indicator. Under the optimal conditions, differential pulse voltammetric responses of MB was proportional to the specific ssDNA arachis sequences in the concentration range from 1.0×10(-11) to 1.0×10(-6) mol L(-1) with the detection limit as 1.5×10(-12) mol L(-1) (3σ). This electrochemical DNA sensor exhibited good stability and selectivity with the discrimination ability of the one-base and three-base mismatched ssDNA sequences. The polymerase chain reaction product of arachis Arabinose operon D gene was successfully detected by the proposed method, which indicated that the electrochemical DNA sensor designed in this paper could be further used for the detection of specific ssDNA sequence.     

层层自组装纳米金与乙酰胆碱酯酶电化学生物传感器检测有机磷农药

采用层层自组装技术制备了快速检测有机磷农药的生物传感器,利用带正电荷的高分子聚电解质聚二烯丙基二甲基氯化铵(PDDA)将乙酰胆碱酯酶(AChE)和金纳米粒子(AuNPs)通过静电力逐层固定到玻碳电极(GCE)表面,并采用交流阻抗和微分脉冲伏安法研究了此生物传感器的电化学行为。由于金纳米粒子优异的电催化性能和良好的生物相容性,使固定化的乙酰胆碱酯酶对其底物具有更高的亲和力和更快的响应速度。实验结果表明:修饰金纳米粒子后,传感器的氧化电流明显增大,在4.6×10-5～5.3×10-3mol/L范围内,固定化酶的抑制率与甲基对硫磷浓度的对数成正比,检出限为7.6×10-6mol/L。该生物传感器具有制备方法简便、成本低、灵敏度高等优点,已成功用于蔬菜样品中甲基对硫磷含量的测定。     

多壁纳米管修饰电极电催化3,4-二羟基苯甲酸研究

应用循环伏安(CV)和方波伏安(SWV)法研究3,4-二羟基苯甲酸(DHBA)在多壁碳纳米管修饰的玻碳电极上的电化学行为.实验表明:该修饰电极对DHBA有较强的电催化作用.由方波伏安法测定的氧化峰电流在DHBA浓度为4.0×10-6~1.0×10-4mol/L和2.0×10-4~8.0×10-4mol/L范围内分段呈线性变化关系;相关系数各为0.9995和0.9992,检测限1.0×10-6mol/L.     

Electrochemical determination of methimazole based on the acetylene black/chitosan film electrode and its application to rat serum samples

A novel method has been developed for the determination of methimazole, which was based on the enhanced electrochemical response of methimazole at the acetylene black/chitosan composite film modified glassy carbon electrode. The electrochemical behavior of methimazole was studied at this film electrode by cyclic voltammetry and differential pulse voltammetry. The experimental results showed that methimazole exhibited a remarkable oxidation peak at 0.63V at the film electrode. Compared with the bare glassy carbon electrode, the oxidation peak current increased greatly, and the peak potential shifted negatively, which indicated that the acetylene black/chitosan film electrode had good catalysis to the electrochemical oxidation of methimazole. The enhanced oxidation current of methimazole was indebted to the nano-porus structure of the composite film and the enlarged effective electrode area. The influences of some experimental conditions on the oxidation of methimazole were tested and the calibration plot was examined. The results indicated that the differential pulse response of methimazole was linear with its concentration in the range of 1.0×10(-7) to 2.0×10(-5)mol/L with a linear coefficient of 0.998, and in the range of 4.0×10(-5) to 3.0×10(-4)mol/L with a linear coefficient of 0.993. The detection limit was 2.0×10(-8)mol/L (S/N=3). The film electrode was used to detect the content of methimazole in rat serum samples by the standard addition method with satisfactory results.