screen-printed electrode Dotaz Zobrazit nápovědu
This article is focused on an optimization of acetylcholinesterase immobilization on screen printed platinum electrodes. An acetylcholinesterase layer cross linked by glutaraldehyde and another non cross linked were compared according to several parameters including background current, current before and current after inhibition by paraoxon. The percentage of inhibition was also calculated. The results obtained confirmed the importance of glutaraldehyde cross linking in the design of the acetylcholinesterase based biosensor.
- MeSH
- acetylcholinesterasa chemie MeSH
- biosenzitivní techniky metody využití MeSH
- butyrylcholinesterasa chemie MeSH
- elektrochemie metody přístrojové vybavení MeSH
- financování organizované MeSH
- glutaraldehyd analogy a deriváty chemie MeSH
- organofosfáty chemie izolace a purifikace MeSH
- reagencia zkříženě vázaná chemie MeSH
Electric spark discharge was employed as a green, fast and extremely facile method to modify disposable graphite screen-printed electrodes (SPEs) with copper, nickel and mixed copper/nickel nanoparticles (NPs) in order to be used as nonenzymatic glucose sensors. Direct SPEs-to-metal (copper, nickel or copper/nickel alloys with 25/75, 50/50 and 75/25wt% compositions) sparking at 1.2kV was conducted in the absence of any solutions under ambient conditions. Morphological characterization of the sparked surfaces was performed by scanning electron microscopy, while the chemical composition of the sparked NPs was evaluated with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The performance of the various sparked SPEs towards the electro oxidation of glucose in alkaline media and the critical role of hydroxyl ions were evaluated with cyclic voltammetry and kinetic studies. Results indicated a mixed charge transfer- and hyroxyl ion transport-limited process. Best performing sensors fabricated by Cu/Ni 50/50wt% alloy showed linear response over the concentration range 2-400μM glucose and they were successfully applied to the amperometric determination of glucose in blood. The detection limit (S/N 3) and the relative standard deviation of the method were 0.6µM and <6% (n=5, 2µM glucose), respectively. Newly devised sparked Cu/Ni graphite SPEs enable glucose sensing with distinct advantages over existing glucose chemical sensors in terms of cost, fabrication simplicity, disposability, and adaptation of green methods in sensor's development.
New screen-printed sensor with a boron-doped diamond working electrode (SP/BDDE) was fabricated using a large-area linear antenna microwave chemical deposition vapor system (LA-MWCVD) with a novel precursor composition. It combines the advantages of disposable printed sensors, such as tailored design, low cost, and easy mass production, with excellent electrochemical properties of BDDE, including a wide available potential window, low background currents, chemical resistance, and resistance to passivation. The newly prepared SP/BDDEs were characterized by scanning electron microscopy (SEM) and Raman spectroscopy. Their electrochemical properties were investigated by cyclic voltammetry and electrochemical impedance spectroscopy using inner sphere ([Fe(CN)6]4-/3-) and outer sphere ([Ru(NH3)6]2+/3+) redox probes. Moreover, the applicability of these new sensors was verified by analysis of the anti-inflammatory drug lornoxicam in model and pharmaceutical samples. Using optimized differential pulse voltammetry in Britton-Robinson buffer of pH 3, detection limits for lornoxicam were 9 × 10-8 mol L-1. The oxidation mechanism of lornoxicam was investigated using bulk electrolysis and online electrochemical cell with mass spectrometry; nine distinct reaction steps and corresponding products and intermediates were identified.
- MeSH
- bor * chemie MeSH
- elektrody MeSH
- elektrolýza * MeSH
- oxidace-redukce MeSH
- Ramanova spektroskopie MeSH
- Publikační typ
- časopisecké články MeSH
Diabetes mellitus can be considered one of the most widespread diseases globally. Hence, the diabetes research is currently focused on developing an effective, low-cost sensor having high stability and suitable analytical characteristics. Screen printed carbon electrodes (SPCEs) embody ideal candidates for insulin determination due to the small area of the working electrode eliminating the solution volume required for the given purpose. Modification of SPCEs by using nanoparticles resulted in an increase of the working electrode surface area and formation of a higher number of active species. The aim of this paper is to examine the impact of a chitosan membrane on the electrochemical determination of insulin on NiO nanoparticles (NiONPs) and multi-walled nanotube (MWCNTs) modified SPCE (NiONPs/MWCNTs/SPCE). This study is primarily conceived to compare the analytical characteristics and stability of NiONPs/chitosan-MWCNTs/SPCE and NiONPs/MWCNTs/SPCE. An electrode modified with chitosan displays a wider linear range, one of 0.25 μM - 5 μM (R2 0.997); a lower limit of detection, 94 nM; a high sensitivity (0.021 μA/μM) and better stability than that of an electrode without chitosan. According to these characteristics, the polymer is considered a necessary compound of the electrochemical insulin sensor, improving the sensor's analytical characteristics.
- MeSH
- biosenzitivní techniky přístrojové vybavení MeSH
- chitosan chemie MeSH
- elektrochemické techniky přístrojové vybavení MeSH
- elektrody MeSH
- inzulin analýza MeSH
- lidé MeSH
- limita detekce MeSH
- membrány umělé * MeSH
- nanočástice chemie MeSH
- nanotrubičky uhlíkové chemie MeSH
- nikl chemie MeSH
- rekombinantní proteiny analýza MeSH
- uhlík chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The detection of cancer antigens is a major aim of cancer research in order to develop better patient management through early disease detection. Many cancers including prostate, lung, and ovarian secrete a protein disulfide isomerase protein named AGR2 that has been previously detected in urine and plasma using mass spectrometry. Here we determine whether a previously developed monoclonal antibody targeting AGR2 can be adapted from an indirect two-site ELISA format into a direct detector using solid-phase printed gold electrodes. The screen-printed gold electrode was surface functionalized with the anti-AGR2 specific monoclonal antibody. The interaction of the recombinant AGR2 protein and the anti-AGR2 monoclonal antibody functionalized electrode changed its electrochemical impedance spectra. Nyquist diagrams were obtained after incubation in an increasing concentration of purified AGR2 protein with a range of concentrations from 0.01 fg/mL to 10 fg/mL. In addition, detection of the AGR2 antigen can be achieved from cell lysates in medium or artificial buffer. These data highlight the utility of an AGR2-specific monoclonal antibody that can be functionalized onto a gold printed electrode for a one-step capture and quantitation of the target antigen. These platforms have the potential for supporting methodologies using more complex bodily fluids including plasma and urine for improved cancer diagnostics.
- MeSH
- biosenzitivní techniky * MeSH
- elektrochemické techniky MeSH
- elektrody MeSH
- kovové nanočástice MeSH
- lidé MeSH
- limita detekce MeSH
- monoklonální protilátky MeSH
- mukoproteiny analýza MeSH
- nádory MeSH
- onkogenní proteiny analýza MeSH
- zlato MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Saliva represents one of the most useful biological samples for non-invasive testing of health status and diseases prognosis and therefore, the development of advanced sensors enabling the determination of biomarkers in unspiked human whole saliva is of immense importance. Herein, we report on the development of a screen-printed graphite sensor modified with carbon nanomaterials generated by spark discharge for the determination of guanine and adenine in unspiked human whole saliva. The designed sensor was developed with a "green", extremely simple, fast (16 s), fully automated "linear mode" sparking process implemented with a 2D positioning device. Carbon nanomaterial-modified surfaces exhibit outstanding electrocatalytic properties enabling the determination of guanine and adenine over the concentration range 5 - 1000 nM and 25 - 1000 nM, while achieving limits of detection (S/N 3) as low as 2 nM and 8 nM, respectively. The sensor was successfully applied to the determination of purine bases in unspiked human whole saliva following a simple assay protocol based on ultrafiltration that effectively alleviates biofouling issues. Recovery was 96-108%.
Flunitrazepam, also known as "Rohypnol" or "Rophy" among other trade and street names, is an extremely potent benzodiazepine that is prescribed to treat severe insomnia. Due to these attributes, flunitrazepam, when is surreptitiously administered to an alcoholic or soft drink, is associated with "drug-facilitated sexual assault". We report here for the first time, a low cost lab-on-a-screen-printed electrochemical cell (SPC) based on iron-sparked graphite working electrode modified with glucose oxidase (GOx) and glucose hydrogel droplets (GluHD) for the detection of flunitrazepam. Iron-spark modification increases the response of the sensor by ca. 3-fold compared with that of the plain electrode, while an in situ deoxygenation process, based on GOx-glucose enzyme reaction, depletes dissolved oxygen. As a result, the method enables interference free voltammetric measurements of the electro reduction of the nitro group of flunitrazepam at ca. -0.71 to -0.78 V vs. Ag printed pseudo reference electrode depending on the sample's matrix, and the detection of the drug at the sub-millimolar level. GOx/GluHD-FeSPC was directly applied to the drop-volume (∼60 μL) detection of flunitrazepam to a wide range of untreated and undiluted spiked samples (Pepsi cola®, Vodka, Whisky, Tequila, Gin, and Rum) of different acidity (pH 2.3-8.4), and alcohol content up to 40% v/v. Data demonstrate the excellent performance of the sensor for point-of-need screening of flunitrazepam and suggest that GOx/GluHD-FeSPC holds promise as an effective analytical tool to prevent phenomena of covert drug administration.
- MeSH
- alkoholické nápoje analýza MeSH
- anxiolytika analýza MeSH
- Aspergillus niger enzymologie MeSH
- biosenzitivní techniky metody MeSH
- elektrochemické techniky metody MeSH
- elektrody MeSH
- flunitrazepam analýza MeSH
- glukosa chemie MeSH
- glukosaoxidasa chemie MeSH
- grafit chemie MeSH
- kyslík chemie MeSH
- lidé MeSH
- limita detekce MeSH
- sycené nápoje analýza MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
A novel enzyme-free electrochemical immunosensor was developed for highly sensitive detection and quantification of human epididymis protein 4 (HE4) in human serum. For the first time, core/shell CdSe/ZnS quantum dots were conjugated with anti-HE4 IgG antibodies for subsequent sandwich-type immunosensing with superparamagnetic microparticles functionalized with anti-HE4 IgG antibodies, which allow rapid and efficient HE4 capture from the sample. Electrochemical detection of anti-HE4 IgG - HE4 - anti-HE4 IgGCdSe/ZnS immunocomplex was performed by recording the current response of Cd(II) ions, released from dissolved quantum dots at screen-printed carbon electrode (SPCE), modified with mercury or bismuth film. The linear range of the detection was from 20 pM to 40 nM with limit of detection of 12 pM using three times the standard deviation of blank criterion at mercury-film SPCE and from 100 pM to 2 nM with limit of detection of 89 pM at bismuth-film SPCE. Proposed electrochemical immunosensor meets the requirements for fast and sensitive quantification of HE4 biomarker in early stage of ovarian cancer and due to the proper sensitivity and specificity presents a promising alternative to enzyme-based probes used routinely in clinical diagnostics.
- MeSH
- biosenzitivní techniky * MeSH
- bismut chemie MeSH
- časná detekce nádoru MeSH
- elektrochemické techniky * MeSH
- elektrody MeSH
- exprese genu MeSH
- imunoanalýza * MeSH
- imunokonjugáty chemie metabolismus MeSH
- kvantové tečky chemie MeSH
- lidé MeSH
- nádorové biomarkery krev genetika MeSH
- nádory vaječníků krev diagnóza genetika patologie MeSH
- proteiny analýza genetika metabolismus MeSH
- protilátky chemie metabolismus MeSH
- rtuť chemie MeSH
- sloučeniny kadmia chemie MeSH
- sloučeniny selenu chemie MeSH
- sloučeniny zinku chemie MeSH
- uhlík chemie MeSH
- vazba proteinů MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
