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1.
Inspired by dual-signaling ratiometric mechanism which could reduce the influence of the environmental change, a novel, convenient, and reliable method for the detection of mercury ions (Hg2+) based on Y-shaped DNA (Y-DNA) was developed. Firstly, the Y-DNA was formed via the simple annealing way of using two different redox probes simultaneously, omitting the multiple operation steps on the electrode. The Y-DNA was immobilized on the gold electrode surface and then an obvious ferrocene (Fc) signal and a weak methylene blue (MB) signal were observed. Upon addition of Hg2+, the Y-DNA structure was transformed to hairpin structure based on the formation of T-Hg2+-T complex. During the transformation, the redox MB gets close to and the redox Fc gets far away from the electrode surface, respectively. This special design allows a reliable Hg2+ detection with a detection range from 1 nM to 5 μM and a low detection limit down to 0.094 nM. Furthermore, this biosensor exhibits good selectivity and repeatability, and can be easily regenerated by using l-cysteine. This study offers a simple and effective method for designing ratiometric biosensors for detecting other ions and biomolecules.  相似文献   

2.
The supramolecular interaction between N,N-diethyl-2-(1-naphthalenyloxy)propanamide (napropamide) and β-cyclodextrin (β-CD) has been studied by spectrofluorimetry. The results showed that β-CD reacted with napropamide to form an inclusion complex with an association constant of 3.18×103 l mol−1. The composition of the complex was 1:1 (β-CD:napropamide). Based on the significant enhancement of fluorescence intensity of napropamide in inclusion complex, a spetrofluorimetric method with high sensitivity and selectivity was developed for the determination of napropamide in aqueous solution. Under the optimum conditions, the complex had excitation and emission maxima at 285 and 339 nm, respectively. The linear range of the method was 3.7-1500 ng ml−1 with a detection limit of 1.1 ng ml−1. The proposed method was successfully used to determine napropamide in river water.  相似文献   

3.
R. Sridhar 《Tetrahedron letters》2005,46(51):8837-8839
A simple and efficient method for the synthesis of β-hydroxy selenides is reported at room temperature in impressive yields for the first time by the highly the regioselective ring-opening of oxiranes with benzeneselenol in water under supramolecular catalysis in the presence of β-cyclodextrin. This is a direct one-pot synthesis of β-hydroxy selenides under mild conditions using water as solvent and has many advantages over the existing methodologies. β-Cyclodextrin can also be recovered and reused.  相似文献   

4.
The behavior of a modified carbon platinum electrode (Pt) for lead(II) determination by square wave voltammetry (SWV) was studied. The modified electrode is obtained by electrodeposition of hydroxyapatite (HAP) on the surface of a bare platinum electrode. The new electrode (HAP/Pt) revealed interesting electroanalytical detection of lead(II) based on the adsorption of this metal onto hydroxyapatite under open circuit conditions. After optimization of the experimental and voltammetric conditions, the best voltammetric responses-current intensity and voltammetric profile were obtained in 0.2 mol L?1 KNO3 with: 30 min accumulation time, 5 mV pulse amplitude and 1 mV s?1 scan rate. The observed detection (DL, 3σ) and quantification (DL, 10σ) limits in pure water were 2.01 × 10?8 and 6.7 × 10?7 mol L?1, respectively. The reproducibility of the proposed method was determined from five different measurements in a solution containing 2.2 × 10?6 mol L?1 lead(II) with a coefficients of variation of 2.08%.The electrochemical of hydroxyapatite at platinum surfaces was characterized, after calcinations 900 °C, by X-ray diffraction, infrared spectroscopy, chemical and electrochemical analysis.  相似文献   

5.
A novel amperometric choline biosensor has been fabricated with choline oxidase (ChOx) immobilized by the sol-gel method on the surface of multi-walled carbon nanotubes (MWCNT) modified platinum electrode to improve the sensitivity and the anti-interferential property of the sensor. By analyzing the electrocatalytic activity of the modified electrode by MWCNT, it was found that MWCNT could not only improve the current response to H2O2 but also decrease the electrocatalytic potential. The effects of experimental variables such as the buffer solutions, pH and the amount of loading enzyme were investigated for the optimum analytical performance. This sensor shows sensitive determination of choline with a linear range from 5.0 × 10−6 to 1.0 × 10−4 mol/L when the operating pH and potential are 7.2 and 0.15 V, respectively. The detection limit of choline was 5.0 × 10−7 mol/L. Selectivity for choline was 9.48 μA·(mmol/L)−1. The biosensor exhibits excellent anti-interferential property and good stability, retaining 85% of its original current value even after a month. It has been applied to the determination of choline in human serum. Translated from Chinese Journal of Analytical Chemistry, 2006, 34(7): 910–914 (in Chinese)  相似文献   

6.
Electrochemical biosensors have made outstanding achievements in recent years. However, the single pursuit of sensitivity and accuracy sometimes cannot meet the detection requirements and achieve high-efficiency measurements. Therefore, no-washing biosensors have more practical advantages. In this work, a disposable point-of-care (POC) electrochemical biosensor was designed for the sensitive and fast detection of neuron-specific enolase (NSE). Fe3O4 and CuS nanoparticles were used as the substrate material for capturing Ab1 and the signal probe for labeling Ab2 respectively. The disposable syringe filter was introduced into the determination procedure for simple sample separation, which easily realized no-washing detection. Due to the syringe filters with 200 nm pore diameter could only allow the small nanoparticles of CuS−Ab2 pass through, the large-sized immunocomplex of Fe3O4−Ab1/NSE/CuS−Ab2 were blocked on the membrane. The uncombined CuS−Ab2 particles were pushed out from the syringe and would occur electron transfer between Cu2+ and Cu+ to generate a current signal detected by the Au electrode. Under optimal conditions, the no-washing biosensor shows a wide linear concentration range (100 fg mL−1∼50 ng mL−1) with the limit of detection of 33 fg mL−1 (S/N=3). Additionally, the biosensor exhibited excellent selectivity, storage stability and reproducibility. The outstanding advantages of the no-washing biosensor make it more suitable for POC testing.  相似文献   

7.
铂纳米颗粒修饰电化学DNA传感器检测大豆中转基因成分   总被引:2,自引:0,他引:2  
用电沉积方法将铂纳米颗粒修饰在玻碳电极表面,然后将花椰菜花叶病毒35S启动子ssDNA片段直接吸附在铂纳米颗粒上,制成特异的电化学DNA传感器。用扫描电子显微镜和循环伏安法对修饰铂纳米颗粒电极进行了表征。ssDNA探针与互补目的ssDNA杂交,以[Co(phen)3]3 (phen=1,10-Phe-nanthroline)为杂交指示剂,用方波伏安法进行检测,表现出良好的响应信号。与在裸玻碳电极上修饰的探针相比,测定目的基因的灵敏度显著提高。传感器对互补目的ssDNA检测的线性范围为2.14×10-9~2.14×10-7mol/L;检出限为1.0×10-9mol/L,与3个碱基错配的DNA序列杂交,观察不到明显的杂交信号。样品DNA经HindⅢ非限制性内切酶酶切后测定,杂交检测信号增大。用传感器检测含量不同的转基因大豆DNA和非转基因大豆DNA的混合溶液,杂交前后的电流差与转基因DNA的含量呈良好线性关系。连续5次测量含有100%转基因大豆DNA杂交后的电信号,相对标准偏差为5.89%,固定探针的电极再生后可重复使用8次。  相似文献   

8.
Tang B  Wang X  Wang G  Yu C  Chen Z 《Talanta》2006,69(1):113-120
An indirect spectrofluorimetric method with high sensitivity and selectivity was developed for the determination of antifungal drug: tolnaftate (TNF), depending on the supramolecualr multirecognition interaction among the anionic surfactant sodium laurylsulfate (SLS), β-cyclodextrin (β-CD) and β-naphthol (ROH). The mechanism of the inclusion was studied and discussed by means of fluorescence spectrum, infra-red spectrograms and 1HNMR spectroscopy. Results showed that the naphthalene ring of ROH and the hydrophobic hydrocarbon chain of SLS were included into the β-CD's cavity to form a ROH:SLS:β-CD ternary inclusion complex with stoichiometry of 1:1:1 at room temperature, which provided effective protection for the excited state of ROH. At λex/λem = 273/360 nm, the fluorescence intensity was linear over a tolnaftate concentration range of 2.46 × 10−9 to 2.10 × 10−6 mol L−1. The detection limit and relative standard deviation was 7.50 × 10−10 mol L−1 and 1.4%, respectively. The interference of 31 foreign substances was slight. The proposed method had been successfully applied to the determination of tolnaftate in artificial mixed samples with almost quantitative recovery.  相似文献   

9.
乙酰胆碱和胆碱化学发光生物传感器的研究   总被引:3,自引:0,他引:3  
宋正华  章竹君  范文哲 《化学学报》1998,56(12):1207-1213
将具有分子识别功能的乙酰胆碱酯酶和胆碱氧化酶及进行换能反应的luminol和Cu^2^+分别固定在多孔玻璃和离子交换剂的柱中,组成流动注射式胆碱和乙酰胆碱化学发光传感器,让传感器分子识别反应和换能反应在各自最佳pH值下进行。这一新型生物传感器优化了发光量子产率,避免了在传感元件上直接发光所产生的散射干扰。测定乙酰胆碱和胆碱的线性范围达到1~1000pmol,检测限为500fmol,每次测定时间为2min,寿命为6个月,已用于鼠脑及人血清中乙酰胆碱和胆碱的测定。  相似文献   

10.
The unique binding event between Escherichia coli single-stranded DNA binding protein (SSB) and single-stranded oligonucleotides conjugated to gold (Au) nanoparticles is utilized for the electrochemical detection of DNA hybridization. SSB was attached onto a self-assembled monolayer (SAM) of single-stranded oligonucleotide modified Au nanoparticle, and the resulting Au-tagged SSB was used as the hybridization label. Changes in the Au oxidation signal was monitored upon binding of Au tagged SSB to probe and hybrid on the electrode surface. The amplified oxidation signal of Au nanoparticles provided a detection limit of 2.17 pM target DNA, which can be applied to genetic diagnosis applications. This work presented here has important implications with regard to combining a biological binding event between a protein and DNA with a solid transducer and metal nanoparticles.  相似文献   

11.
A novel gelation occurs in water during supramolecular self-assemblies of α-cyclodextrins being threaded onto amphiphilic LA-PEG-LA copolymer end-capped with methacryloyl groups. The rheologic studies show that the gels are thixotropic and reversible. While exposed to UV irradiation with a photoinitiator added in advance, they can be photopolymerized in situ to give rise to chemically cross-linked biodegradable hydrogels with the markedly improved mechanical strength. The gels formed prior to and after UV irradiation are characterized using FTIR, 1H NMR, WAXD and TGA techniques. The swelling ratio and in vitro degradation of the photocured hydrogels are also investigated. It appears that both physical and chemical gels have the potential to be used as injectable biomaterials.  相似文献   

12.
Cold nanoparticles(AuNPs) functionalized with supiamolecular macrocycles are versatile and diverse hybrid nanoinaterials,which combine and enhance the characteristics of the two components.In this mini-review,we summarize the recent research progress on the synthesis and assembly of AuNPs functionalized with different supramoleciilar macrocyclic compounds,i.e.,crown ethers,cyclophanes, cyclodextrins(CDs),cucurbit[n]urils(CB[n]),calix[n]arenes,and pillar[n]arenes(P[n]A).Meanwhile, applications of these supramoleciilar hybrid nanomaterials in the fields of sensors,biomedicine and plasmonic devices are also presented.  相似文献   

13.
Wu S  Lan X  Cui L  Zhang L  Tao S  Wang H  Han M  Liu Z  Meng C 《Analytica chimica acta》2011,(2):170-176
Electrochemical reduced β-cyclodextrin dispersed graphene (β-CD-graphene) was developed as a sorbent for the preconcentration and electrochemical sensing of methyl parathion (MP), a representative nitroaromatic organophosphate pesticide with good redox activity. Benefited from the ultra-large surface area, large delocalized π-electron system and the superconductivity of β-CD-graphene, large amount of MP could be extracted on β-CD-graphene modified electrode via strong π–π interaction and exhibited fast accumulation and electron transfer rate. Combined with differential pulse voltammetric analysis, the sensor shows ultra-high sensitivity, good selectivity and fast response. The limit of detection of 0.05 ppb is more than 10 times lower than those obtained from other sorbent based sensors. The method may open up a new possibility for the widespread use of electrochemical sensors for monitoring of ultra-trace OPs.  相似文献   

14.
Haghighi B  Bozorgzadeh S 《Talanta》2011,85(4):2189-2193
ZnO nanoparticles (nanoZnO) were decorated on multiwalled carbon nanotubes (MWCNTs) and then the prepared nano-hybrids, nanoZnO-MWCNTs, were immobilized on the surface of a glassy carbon electrode (GCE) to fabricate nanoZnO-MWCNTs modified GCE. The prepared electrode, GCE/nanoZnO-MWCNTs, showed excellent electrocatalytic activity towards luminol electrochemiluminescence (ECL) reaction. The electrode was then further modified with lactate oxidase and Nafion to fabricate a highly sensitive ECL lactate biosensor. Two linear dynamic ranges of 0.01-10 μmol L−1 and 10-200 μmol L−1 were obtained for lactate with the correlation coefficient better than 0.9996. The detection limit (S/N = 3) was 4 nmol L−1 lactate. The relative standard deviation for repetitive measurements (n = 6) of 10 μmol L−1 lactate was 1.5%. The fabrication reproducibility for five biosensors prepared and used in different days was 7.4%. The proposed ECL lactate biosensor was used for determination of lactate in human blood plasma samples with satisfactory results.  相似文献   

15.
A novel and highly efficient allylation of aldehydes using allyltributyltin has been developed in aqueous medium catalyzed by β-cyclodextrin in the presence of HCl without any metal catalysts to afford the corresponding homoallylic alcohols in good yields. The β-cyclodextrin can be recovered and reused for a number of runs without significant loss of activity.  相似文献   

16.
用纳米金溶胶与聚乙烯醇缩丁醛(PVB)构成复合固酶基质,采用溶胶-凝胶法固定葡萄糖氧化酶(GOx)于铂电极表面,并在葡萄糖溶液中加入高氯酸·三-2,2′-联吡啶合钴(Ⅲ)作为电子媒介体,制成了高灵敏的葡萄糖生物传感器.葡萄糖氧化酶吸附在纳米金颗粒表面上稳定且保持其生物活性;而电子媒介体的存在,显著提高了传感器的响应灵敏度.该传感器对葡萄糖响应的线性范围为1.2×10-8~6.2×10-6 mol/L,检出限6.2×10-9 mol/L(S/N=3).该生物传感器有效消除了抗坏血酸、尿酸的干扰,可用于人体血清中葡萄糖的测定.  相似文献   

17.
β-Thalassemia is an inherited disorder mainly caused by mutations in the gene of the β-globin chain of adult haemoglobin (HbA). Clinically, β-thalassemia can be a mild or silent condition, or it can cause severe diseases, leading to transfusion dependence. Studies at the gene level have identified a large number of variations in the β-globin gene in different populations. In the Mediterranean area one of the most common mutation is the C → T substitution in the codon 39 of the gene.A new procedure for detecting codon 39 mutation in the β-globin gene is reported, based on a DNA piezoelectric biosensor. An oligonucletidic probe (25-mer), specific for the region around codon 39, is immobilised on the gold surface of a piezoelectric quartz crystal. The hybridisation between the immobilised probe and the complementary strand in solution is detected recording the variations of the crystal frequency.Experiments with synthetic oligonucleotides were initially performed. Distinguishable frequency shifts were obtained from the interaction between the immobilised probe and the complementary and the mismatch oligonucleotides. A solution containing 50% of both the oligonucleotides has been also tested and distinguished from the others evaluating the resulting signals. Experiments with non-complementary oligonucleotides gave no signal variation. The biosensor was able to distinguish between sequences differing in only one base also using polymerase chain reaction-amplified samples [771 base pairs (bp)] of DNA extracted from human blood of thalassemic and healthy (normal) patients or patients with β-thalassemia traits.The optimised DNA piezoelectric biosensor has been successfully applied to the determination of one of the most frequent mutation characteristic of β-thalassemia in the Mediterranean population.  相似文献   

18.
Capecitabine, known as an anti-cancer drug, despite clinical evidence in the general society of patients, the absence of specific data from the perception of increased toxic effects in older people and randomized trials, can be harmful to the body. So, its measurement is essential. A novel electrochemical sensor was fabricated based on glassy carbon electrode (GCE) decorated by molecularly imprinted polymer (MIP)-coated magnetic nanocomposite of iron (II, III) oxide @graphene oxide (Fe3O4@GO) for the detection of capecitabine. The MIP was deposited on the surface of core@shell nanocomposite by non-covalent imprinting process. Fe3O4@GO@MIP composite was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) techniques. The electrochemical performance of proposed sensor was investigated by cyclic and square wave voltammetry techniques. Several parameters such as the electrochemical behavior of the modified electrodes, the type and pH value of supporting electrolyte and scan rates were studied. Under the optimized conditions, the linear range and detection limit were obtained 1.0–100.0 nM and 0.324 nM, respectively. The proposed electrode was successfully applied to the quantification of capecitabine in health human plasma and pharmaceutical samples.  相似文献   

19.
A highly sensitive and label-free impedimetric biosensor is achieved based on an adjunct probe attached nearby the capture probe. In this work, the adjunct probe was co-assembled on the surface of gold electrode with the capture probe hybridized with the reporter probe, and then 6-mercapto-1-hexanol was employed to block the nonspecific binding sites. When target DNA was added, the adjunct probe functioned as a fixer to immobilize the element of reporter probe displaced by the target DNA sequences and made the reporter probe approach the electrode surface, leading to effective inhibition of charge transfer. The increase in charge transfer resistance is related to the quantity of the target DNA in a wide range. The linear range for target DNA with specific sequences was from 0.1 nM to 0.5 μM with a good linearity (R = 0.9988) and a low detection limit of 6.3 pM. This impedimetric biosensor has the advantages of simplicity, sensitivity, good selectivity, and large dynamic range.  相似文献   

20.
This paper presents a microsensor chip integrated with a gold nanoparticles‐modified ultramicroelectrode array (UMEA) as the working electrode for the detection of copper ions in water. The microsensor chip was fabricated with Micro‐Electromechanical System technique. Gold nanoparticles were electrodeposited onto the surface of UMEA at a constant potential of ?0.3 V. The ratio d/Rb of interelectrode spacing (d) over the individual electrode’s radius (Rb) was investigated to improve the electrochemical performance. The UMEA with a d/Rb of 20 showed the best hemispherical diffusion mode, resulted in fast response time and high current response. The gold nanoparticles increased the active surface area of UMEA by not changing the geometries of UMEA, and the current response was increased further. Incorporating the optimized characteristic of UMEA and gold nanoparticles, the microsensor showed a good linear range from 0.5 to 200 µg L?1 of copper ions in the acetate buffer solutions with the method of square wave stripping voltammetry. Compared with the gold nanoparticles‐modified disk electrode, the gold nanoparticles‐modified UMEA showed higher sensitivity (0.024 µA mm?2 µg?1 L) and lower limit of detection (0.2 µg L?1). Water samples from river water and tap water were analyzed by the microsensor chip with recovery ranging from 100.7 % to 107.8 %.  相似文献   

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