共查询到20条相似文献,搜索用时 15 毫秒
1.
A highly selective electrochemical sensor was fabricated based on a modified carbon paste electrode with zinc ferrite nanoparticles (ZnFe2O4 NPs). The nanocomposite has attractive properties such as high surface-to-volume ratio and good electrocatalytic activity towards the drugs acetaminophen (AC), epinephrine (EP), and melatonin (MT), best at working voltages of 0.35, 0.09 and 0.55 V (vs. Ag/AgCl), respectively. The linear ranges (and detection limits) are 6.5–135 (0.4) μmol L?1 for AC, 5–100 (0.7) μmol L?1 for EP, and 6.5–145 (3) μmol L?1 for MT. 相似文献
2.
The work describes a hybrid electrochemical sensor for highly sensitive detection of the anesthetic lidocaine (LID). Porous carbon (PC) was synthesized from an isoreticular metal-organic framework-8 (IRMOF-8) and drop cast onto a glassy carbon electrode (GCE). A layer of a molecularly imprinted polymer (MIP) layer was then fabricated in situ on the modified GCE by electro-polymerization, with LID acting as the template and resorcinol as the functional monomer. Hexacyanoferrate is used as an electrochemical probe. The electrical signal (typically acquired at 0.335 V vs. SCE) increases linearly in the 0.2 pM to 8 nM LID concentration range, with a remarkable 67 fM detection limit (at an S/N ratio of 3). The sensor is stable and selective. Eventually, rapid and accurate detection of LID in spiked real samples was successfully realized. 相似文献
3.
A composite consisting of chitosan containing azidomethylferrocene covalently immobilized on sheets of reduced graphene oxide was drop-casted on a polyester support to form a screen-printed working electrode that is shown to enable the determination of nitrite by cyclic voltammetry and chronoamperometry. Both reduction and oxidation of nitrite can be accomplished due to the high electron-transfer rate of this electrode. Under optimal experimental conditions (i.e. an applied potential of 0.7 V vs. Ag/AgCl in pH 7.0 solution), the calibration plot is linear in the 2.5 to 1450 μM concentration range, with an ~0.35 μM limit of detection (at a signal-to-noise ratio of 3). The sensor was successfully applied to the determination of nitrite in spiked mineral water samples, with recoveries ranging between 95 and 101 %. 相似文献
4.
A binary nanocomposite of type copper tungstate and polyaniline (CuWO4@PANI) is described that was obtained by single step polymerization on the surface of a glassy carbon electrode (GCE). The resulting electrode is shown to be a viable tool for voltammetric sensing of quercetin (Qn) in blood, urine and certain food samples. The nanocomposite was characterized by UV-visible absorption spectroscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and high-resolution transmission electron microscopy. Differential pulse voltammetry was applied to quantify Qn, typically at the relatively low working potential of 0.15 V (vs. Ag/AgCl). The modified GCE has a wide analytical range (0.001–0.500 μM) and a low detection limit (1.2 nM). The sensor is reproducible, selective and stable. This makes it suitable for determination of Qn in real samples without complicated sample pretreatment. 相似文献
5.
A photoelectrochemical wire microelectrode was constructed based on the use of a TiO2 nanotube array with electrochemically deposited CdSe semiconductor. A strongly amplified photocurrent is generated on the sensor surface. The microsensor has a response in the 0.05–20 μM dopamine (DA) concentration range and a 16.7 μM detection limit at a signal-to-noise ratio of 3. Sensitivity, recovery and reproducibility of the sensor were validated by detecting DA in spiked human urine, and satisfactory results were obtained. 相似文献
6.
Under visible-light irradiation, a cathodic photoelectrochemical (PEC) sensor is presented for highly sensitive determination of Cr(VI) at a potential of ?0.25 V (vs SCE). PbS quantum dots (QDs) were capped with mercaptoacetic acid and assembled on the surface of an indium tin oxide (ITO) electrode via the linker poly(diallyl dimethyl ammonium chloride) providing a photoactive sensor. Cr(VI) accepts the photoelectrons generated by the PbS QDs. This promotes the separation of electron holes and enhances the cathodic photocurrent generated by a 470-nm LED. The sensor has 10 pM detection limit and a linear working range from 0.02 nM to 2 μM of chromate. The method was successfully applied to the determination of Cr(VI) and total chromium in spiked environmental water samples. 相似文献
7.
The authors describe a surface plasmon resonance (SPR) based aptasensor for the carcinogenic mycotoxin aflatoxin B1 (AFB1) in a direct assay format. The aptamer is immobilized on the surface of a commercial sensor chip, and the SPR signal increases on binding of AFB1. The sensor chip can be fully regenerated by passing a flow of buffer over it upon which bound AFB1 dissociates from the aptamer. The biosensor works in the 0.4 nM to 200 nM AFB1 concentration range and has a 0.4 nM detection limit. It allows AFB1 to be determined in complex samples such as diluted red wine and beer. The assay is sensitive, and the chip is easily regenerated and stable. The method therefore overcomes certain limitations of antibody-based SPR assays and of competitive SPR assays for AFB1. 相似文献
8.
Xiaoyu?Chen Qingquan?Liu Minghuan?Liu Xiaoyan?Zhang Suying?Lin Yisong?Chen Junyang?Zhuang Da-Peng?Yang
The authors describe an amperometric sensor for dopamine (DA) by employing olive-like Fe2O3 microspheres (OFMs) as the electrocatalyst for DA oxidization. The OFMs were prepared by using a protein templated method. The structure and properties of the OFMs were characterized by scanning electron microscopy, X-ray powder diffraction, energy dispersive x-ray spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The OFMs possess excellent catalytic activity towards DA oxidization due to their unique morphology. The sensor responds to DA within less than 5 s. The sensor, best operated at a voltage of +0.2 V (vs. SCE) responds linearly in the 0.2 to 115 μM DA concentration range and has a 30 nM detection limit. The selectivity, reproducibility and long-term stability of the sensor are acceptable. It performs well when applied to spiked human urine samples. 相似文献
9.
Zhenjing Zhuang Haiqin Lin Xiong Zhang Fei Qiu Huiyong Yang 《Mikrochimica acta》2016,183(10):2807-2814
The authors describe a method for the fabrication of a nanohybrid composed of carbon dots (C-dots) and gold nanoparticles (AuNPs) by in-situ reduction of C-dots and hydroauric acid under alkaline conditions. The process does not require the presence of surfactant, stabilizing agent, or reducing agent. The hybrid material was deposited in a glassy carbon electrode (GCE), and the modified GCE exhibited good electrocatalytic activity toward the oxidation of nitrite due to the synergistic effects between carbon dots and AuNPs. The findings were used to develop an amperometric sensor for nitrite. The sensor shows a linear response in the concentration range from 0.1 μmol?L-1 to 2 mmol?L-1 and a low detection limit of 0.06 μmol?L-1 at the signal-to-noise ratio of 3. 相似文献
10.
A highly selective and sensitive aptasensor is described for voltammetric determination of the pesticide chlorpyrifos (CPS). The sensor was constructed by modifying a glassy carbon electrode (GCE) with gold nanorods and a polymer that was molecularly imprinted with an aptamer against CPS. This results in double specific recognition. Under optimal conditions and a working potential as low as 0.22 V (vs. Ag/AgCl), the nanotools has a dynamic range that covers the 1.0 fM - 0.4 pM CPS concentration range, and the detection limit is 0.35 fM. This is lower than any of the previously reported methods. This MIP-aptasensor is selective over structural analogs, stable, and adequately reproducible. It was successfully applied to the determination of CPS in spiked food samples. 相似文献
11.
Mojtaba Mahyari 《Mikrochimica acta》2016,183(8):2395-2401
The authors describe a method for amperometric determination of thiodiglycol (TDG), the main hydrolysis product of sulfur mustard. The electrode consists of a mixture of graphene nanosheets, silver nanoparticles and the ionic liquid octylpyridinium hexafluorophosphate. Electrochemical oxidation of TDG was performed by cyclic voltammetry at pH 4 and revealed a pair of well-defined redox peaks at potentials of 0.43 and 0.19 V (vs. Ag/AgCl). Amperometric detection was accomplished over a dynamic range that is linear in the 10–3700 μM concentration range. The detection limit (at an S/N of 3) is 6 μM. The electrode was applied to the determination of TDG in (spiked) waste water and gave recoveries that ranged from 98.2 to 103.3 %. 相似文献
12.
Huisoo Jang Cheol Hwan Kwak Gibum Kim Sun Min Kim Yun Suk Huh Tae-Joon Jeon 《Mikrochimica acta》2016,183(9):2649-2654
The authors describe an SPR sensor chip coated with gold nanoparticles (AuNPs) that enables highly sensitive determination of genetically modified (GM) crops. Detection is based on localized surface plasmon resonance (LSPR) with its known sensitivity to even minute changes in refractive index. The device consists of a halogen light source, a light detector, and a cuvette cell that contains a sensor chip coated with AuNPs. It is operated in the transmission mode of the optical path to enhance the plasmonic signal. The sample solution containing target DNA (e.g. from the GM crop) is introduced into the cuvette with the sensor chip whose surface was functionalized with a capture DNA. Following a 30-min hybridization, the changes of the signal are recorded at 540 nm. The chip responds to target DNA in the 1 to 100 nM concentration range and has a 1 nM detection limit. Features of this sensor chip include a short reaction time, ease of handling, and portability, and this enables on-site detection and in-situ testing. 相似文献
13.
Ali?Karimizefreh Farzaneh?Aghakhani?Mahyari Maryam?VaezJalali Raheleh?Mohammadpour Pezhman?Sasanpour
The authors describe an impedimetric method for the quantitation of the DNA of the human papilloma virus (HPV) type 16. A glassy carbon electrode (GCE) was modified with gold nanosheets and is shown to be superior to a common gold disk electrode. A single-stranded 25mer oligonucleotide (ssDNA) acting as the probe DNA was immobilized via its thiolated 5′ end on both electrodes. After hybridization with target (analyte) DNA, electrochemical impedance spectra were acquired in the presence of hexacyanoferrate as a redox marker. The sensor can distinguish between complementary, non-complementary and single base pair mismatches of HPV ssDNA. At a 1 mM hexacyanoferrate concentration, the biosensors respond to target DNA in the 1 μM to 1 pM concentration range, and the detection limit is 0.15 pM. The results illustrate that the use of gold nanosheets on a GCE distinctly improves the detection and differentiation of HPV compared to using bare gold. 相似文献
14.
CdSe:Eu nanocrystals were successfully synthesized and characterized by transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectric spectroscopy. The CdSe:Eu nanocrystals showed enhanced green electrochemiluminescence (ECL) intensity when compared to pure CdSe nanocrystals. Further, the nanocrystals were used to design an ECL immunosensor for the detection of carcinoembryonic antigen (CEA) that has a linear response over the 1.0 fg·mL?1 to 100 ng·mL?1 CEA concentration range with a 0.4 fg·mL?1 detection limit. The assay was applied to the determination of CEA in human serum samples. 相似文献
15.
The authors report on a novel sorbent (thermally treated natural zeolite; clinoptilolite) for use in dispersive micro-solid phase extraction (D-μ-SPE) of polycyclic aromatic hydrocarbons (PAHs) from water samples. The method was applied to the D-μ-SPE of 16 priority PAHs which then were quantified by gas chromatography with mass spectrometric detection (GC-MS). The method was validated in terms of specificity and selectivity, linearity and linear range, accuracy, precision, uncertainty, limits of detection and quantification. Figures of merit include (a) linear analytical ranges between 2.08 and 208 ppb, and (b) detection limits in the range from 0.01 to 0.92 ppb. The method was successfully applied to the determination of PAHs in river waters. 相似文献
16.
The authors report that sulfide ions are capable of inhibiting the peroxidase-like activity of copper nanoclusters (CuNCs). The catalytic activity of CuNCs toward the oxidation of the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine by H2O2 is remarkably decreased in the presence of sulfide. Based on this finding, a colorimetric assay was developed for the rapid determination of sulfide. Best operated at a wavelength of 652 nm, it has a 0.5 μM detection limit. The method is highly selective and has been successfully applied to the quantification of sulfide in environmental water samples. 相似文献
17.
The authors describe a fluorescent probe for sulfide that is based on carboxy-functionalized semiconducting polymer dots (P-dots). The dots were prepared from carboxy-functionalized poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-2,1′-3-thiadiazole)] (referred to as COOH-PFBT) via co-precipitation. The P-dots aggregate on addition of Cu(II) ions and their green fluorescence (with excitation/emission peaks at 455/540 nm) is then quenched. Fluorescence is restored on addition of sulfide to the aggregates due to the formation of CuS. This quenching-recovery (“off-on”) mechanism forms the basis for a new sulfide detection scheme. Fluorescence increases linearly in the 1.25 to 75.0 μM sulfide concentration range, with a 0.45 μM detection limit. Good selectivity over other anions is demonstrated. The method shows recoveries ranging between 98.6% and 105.7% when applied to the determination of sulfide in spiked real water samples. 相似文献
18.
A voltammetric sensor is described for the quantitation of propyl gallate (PG). A screen-printed carbon electrode (SPCE) was modified with reduced graphene sheets that were decorated with cobalt diselenide nanoparticles (CoSe2@rGO). The material was hydrothermally prepared and characterized by several spectroscopic techniques. The modified SPCE displays excellent electrocatalytic ability towards PG. Differential pulse voltammetry, with a peak voltage at 0.34 V (vs. Ag/AgCl) has a sensitivity of 12.84 μA·μM?1·cm?2 and a detection limit as low as 16 nM. The method is reproducible, selective, and practical. This method was applied to the determination of PG in spiked meat samples, and the result showed an adequate recovery. 相似文献
19.
Shuhuai Li Chunhua Liu Guihao Yin Jinhui Luo Zhenshan Zhang Yixian Xie 《Mikrochimica acta》2016,183(12):3101-3109
The authors describe an electrochemical sensor for the neonicotinoid insecticide imidacloprid (IMI) based on Pt-In catalytic nanocomposite film and Bromophenol blue amplification. The Pt-In nanocomposite film was deposited on the surface of a modified glassy carbon electrode. The composite molecularly imprinted polymer (MIP) was prepared by electro-polymerization using bromophenol blue doped o-aminophenol as functional monomer and 4-tert-butylcalix[6]arene-IMI supramolecular inclusion complex as template molecule. The experimental results showed that the current intensity of IMI was clearly amplified in the potential range from ?0.3 to ?1.8 V, because of the double amplification, based on the Pt-In film and Bromophenol blue catalysis. Moreover, the double recognition ability of the sensor, which relied on the MIP and the vacuum structure of 4-tert-butylcalix[6]arene, effectively increased the specific recognition performance. The feasibility of its practical applications has been demonstrated by the analysis of vegetable samples. 相似文献
20.
The authors describe a microsensor for the determination of biochemical oxygen demand. Different from established BOD detection schemes that incorporate a film of immobilized microbes, the sensitive element of this BOD microsensor consists of magnetite-functionalized Bacillus subtilis that can be immobilized and regenerated on an ultramicroelectrode array (UMEA). Modification and regeneration are magnetically controlled. The oxygen consumed is amperometrically quantified by using an UMEA modified with palladium nanoparticles and reduced carboxy graphene. The assay can be performed within 5 min owing to the fast mass transfer of the magnetite-functionalized microbes on the surface of the UMEA. The calibration plot, best acquired at a voltage of -0.4 V vs. Ag/AgCl, is linear in the 2 to 15 mg?L?1 BOD concentration range. A critical comparison with other BOD sensor shows the sensitivity of this sensor to be largely improved. It was successful applied to the determination of BOD in spiked water samples. 相似文献