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Study on the preparation of CdTe nanocrystals on the surface of mesoporous silica and evaluation as modifier of carbon paste electrodes
摘要： Here CdTe nanocrystals were grown onto mesoporous silicas. The influence of the surface areas, volumes and pore diameters of the silica matrices on the spectroscopic properties of CdTe was evaluated. Emission properties of the CdTe were found to depend on the textural properties of silicas. Electrochemical characterization of different electrodes (unmodified carbon paste, and carbon paste modified with the mesoporous silica and with CdTe anchored onto mesoporous silica) evidenced that the presence of CdTe nanocrystals lead to a significant increase of the anodic peak referring to Cu2+ detection. The electrode with optimal characteristics responded to Cu2+ in the linear range from 5.0 × 10?8 to 2.3 × 10?6 mol L?1 and the calculated limit of detection was 6.4 × 10?8 mol L?1. The method developed here proved to be efficient for monitoring Cu2+ in sugar cane spirit (cacha?a), with quantitative results comparable to those obtained from Flame Atomic Absorbtion Spectroscopy.
关键词： CdTe nanocrystals,Mesoporous silicas,Electrochemical sensors
更新于2025-09-23 15:23:52
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Photo-refreshable electrochemical sensor based on composite electrode of carbon nanotubes and TiO2 nanoparticles
摘要： Surface fouling and passivation on the electrode during electrochemical process is a major challenge for the practical applications of electrochemical sensors. Herein, a photo-refreshable electrochemical sensor was presented based on carbon nanotubes/TiO2 nanoparticles (CNTs/TiO2-NPs) composite electrode, which not only exhibits high electrochemical activity towards the determination of 5-hydroxytryptamine and dopamine, but also displays excellent reproducibility in the surface electrochemical monitoring without damaging microstructure. The linear range for 5-hydroxytryptamine determination is 0.5-400 μM (R=0.991) under UV light irradiation with a detection limit of 0.47 μM (S/N=3). The CNTs/TiO2-NPs electrode also shows excellent response to dopamine, with the linear range of 0.05 μM to 100 μM and a detection limit of 0.022 μM (S/N =3). The high performance of this photo-refreshable electrochemical sensor should be attributed to the excellent photocatalytic activity of the TiO2-NPs and the high electrochemical activity of CNTs.
关键词： carbon nanotubes,photocatalysis,TiO2 nanoparticles,electrochemical sensors,surface fouling
更新于2025-09-23 15:22:29
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Sensing of Furfural by Molecularly Imprinted Polymers on Plasmonic and Electrochemical Platforms
摘要： The goal of this work is to test the possibility of selective detection of furfural (2-FAL) in aqueous solutions, with a molecularly imprinted polymer (MIP) receptor exploiting two different transduction methods, for food safety applications. In particular, sensors with electrochemical and surface plasmon resonance (SPR) transduction are considered. Two concentration ranges could be investigated by the different sensing approaches since the detectable concentration level depends on the sensitivity of the detection technique employed. The determination of 2-FAL at different concentration levels in the aqueous medium of interest, as for example beverages, is becoming a very crucial task not only for the relevance of furanic compounds in affecting the flavor but also for their possible toxic and carcinogenic effects on the human beings. For these reasons, their determination by a fast, easy and low-cost method is of interest. The sensor methods here proposed appears to be particularly suitable, since, although together and not individually, they allow the determination in a wide concentration range.
关键词： furfural (2-FAL),electrochemical sensors,molecularly imprinted polymers (MIPs),optical-chemical sensors,plastic optical fibers (POFs),surface plasmon resonance (SPR)
更新于2025-09-23 15:19:57
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Carbon and graphene quantum dots: a review on syntheses, characterization, biological and sensing applications for neurotransmitter determination
摘要： Neuro-transmitters have been considered to be essential biochemical molecules, which monitor physiological and behavioral function in the peripheral and central nervous systems. Thus, it is of high pharmaceutical and biological significance to analyze neuro-transmitters in the biological samples. So far, researchers have devised a lot of techniques for assaying these samples. It has been found that electro-chemical sensors possess features of robustness, selectivity, and sensitivity as well as real-time measurement. Graphene quantum dots (GQDs) and carbon QDs (CQDs) are considered some of the most promising carbon-based nanomaterials at the forefront of this research area. This is due to their characteristics including lower toxicity, higher solubility in various solvents, great electronic features, inertness, high specific surface areas, plenty of edge sites for functionalization, and strong chemical versatility, in addition to their ability to be modified via absorbent surface chemicals and the addition of modifiers or nano-materials. Hence in the present review, the synthesis methods of GQDs and CQDs has been summarized and their characterization methods also been analyzed. The applications of carbon-based QDs (GQDs and CQDs) in biological and sensing areas, such as biological imaging, drug/gene delivery, antibacterial and antioxidant activity, photoluminescence sensors, electrochemiluminescence sensors and electrochemical sensors, have also been discussed. This study then covers sensing features of key neurotransmitters, including dopamine, tyrosine, epinephrine, norepinephrine, serotonin and acetylcholine. Hence, issues and challenges of the GQDs and CQDs were analyzed for their further development.
关键词： Carbon quantum dots,Graphene quantum dots,Neurotransmitters,Biological applications,Sensing applications,Electrochemical sensors
更新于2025-09-23 15:19:57
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Nanomaterials based optical and electrochemical sensing of histamine: Progress and perspectives
摘要： Histamine is known to be a principal causative agent associated with marine food poisoning outbreaks worldwide, which is typically formed in the contaminated food by decarboxylation of histidine by bacterial histidine decarboxylase. Upon quantification of histamine in different food products, one can comment on the quality of the food and use it as an indicator of the good manufacturing practices and the state of preservation. The United States Food and Drug Administration (FDA) has established 50 ppm (50 mg/kg) of histamine as the chemical index for fish spoilage. Consumption of foods containing histamine higher than the permissible limit can cause serious health issues. Several methods have been developed for the determination of histamine in a variety of food products. The conventional methods for histamine detection such as thin layer chromatography, capillary zone electrophoresis, gas chromatography, colorimetry, fluorimetry, ion mobility spectrometry, high-performance liquid chromatography, and enzyme-linked immunosorbent assay (ELISA), are being used for sensitive and selective detection of histamine. However, there are a number of disadvantages associated with the conventional techniques, such as multi-step sample processing and requirement of expensive sophisticated instruments, which restrict their applications at laboratory level only. In order to address the limitations associated with the traditional methods, new approaches have been developed by various research groups. Current advances in nanomaterial-based sensing of histamine in different food products have shown significant measurement accuracy due to their high sensitivity, specificity, field deployability, cost and ease of operation. In this review, we have discussed the development of nanomaterials-based histamine sensing assays/strategies where the detection is based on optical (fluorescence, surface enhanced Raman spectroscopy (SERS), localized surface plasmon resonance) and electrochemical (impedimetric, voltammetry, potentiometric, etc.). Further, the advantages, disadvantages and future scope of the nanomaterials-based histamine sensor research are highlighted.
关键词： Optical sensors,Nanosensor,Nanoparticles,Food quality control,Electrochemical sensors,Histamine
更新于2025-09-19 17:15:36
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[IEEE 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - Berlin, Germany (2019.6.23-2019.6.27)] 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII) - A High-Performance Self-Powered UV Photodetector Based on Self-Doping TIO <sub/>2</sub> Nanotube Arrays
摘要： In this paper, we present a high-performance self-powered ultraviolet (UV) photodetector using electrochemical micro-porous-channel arrays based on a cost-effective and environment-friendly black TiO2 nanotube arrays (BTNAs) and polysulfide (S2-/Sx2-) electrolyte. By self-doping TiO2 the concentration and lifetime of UV photo-generated carriers are increased due to increasing oxygen vacancies and Ti3+ defects in BTNAs, effectively enhancing the carrier transport and multiple exciton effect of carriers, and thus the self-powered UV photodetector based on electrochemical micro-porous-channel arrays demonstrates a high photoresponsivity of ~22 mA/W and high-speed photoresponse of ~4 ms in rise and decay time.
关键词： TiO2 nanotube arrays,self-powered sensors,electrochemical sensors,ultraviolet photodetector
更新于2025-09-16 10:30:52
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Biocompatible Palladium Telluride Quantum Dot-Amplified Biosensor for HIV Drug
摘要： Indinavir (IDV) is a potent and well-tolerated protease inhibitor antiretroviral (ARV) drug used as a component of the highly active antiretroviral therapy (HAART) of human immunodeficiency virus (HIV). It undergoes hepatic first-pass metabolism that is catalysed by microsomal cytochrome P450-3A4 enzyme (CYP3A4), which results in pharmacokinetics that may be favourable or adverse. Therapeutic drug monitoring (TDM) of IDV during HIV treatment is therefore critical, in order to prevent the adverse effects of its first-pass metabolism and optimise an individual’s dosage regime. Biosensors are now the preferred diagnostic tools for TDM assessment at point-of-care, due to their high sensitivity and real-time response. An electrochemical biosensor for IDV was prepared by depositing a thin film of CYP3A4 (a thiolate enzyme) and thioglycolic acid-capped palladium telluride quantum dot (TGA-PdTeQD) on a cysteamine-functionalised gold disk electrode (Cyst|Au) using a combination of thiol and carbodiimide covalent bonding chemistries. The electrochemical signatures of the biosensor (CYP3A4|TGA-PdTeQD|Cyst|Au) were determined by cyclic voltammetry (CV) that was performed at a scan rate of 500 mV s?1, and the sensor responses at the characteristic reduction peak potential value of ? 0.26 V were recorded. The sensitivity, linear range (LR) and limit of detection (LOD) values of the indinavir biosensor were 4.45 ± 0.11 μA nM?1 IDV, 0.5–1.0 nM IDV (i.e. 3.6 × 10?4–7.1 × 10?4 mg L?1 IDV) and 4.5 × 10?4 mg L?1 IDV, respectively. The values of the two analytical parameters (LR and LOD) of the biosensor were by up to four orders of magnitude lower than the maximum plasma concentration (Cmax) values of indinavir (0.13–8.6 mg L?1 IDV). The IDV biosensor was successfully used to detect IDV in human serum samples containing dissolved indinavir tablet. This, therefore, indicates the indinavir biosensor’s suitability for TDM applications, using samples obtained within 1–2 h of drug intake at point-of-care, for which very low levels of the drug are expected.
关键词： Human serum,Limit of detection,Indinavir,Palladium telluride quantum dot,Cyclic voltammetry,Electrochemical sensors,Cytochrome P450-3A4
更新于2025-09-16 10:30:52
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Reagentless fabrication of a porous graphene-like electrochemical device from phenolic paper using laser-scribing
摘要： This study fabricated a portable, high-performance, and reagentless electrochemical devices using CO2 laser-scribing process, which allowed localized carbonization of a non-conductive and low-cost polymer platform, i.e., phenolic-paper. The carbonized material was extensively characterized by Raman spectroscopy, XPS, XRD, SEM, and electrochemical impedance spectroscopy. The carbon-based electrodes were obtained from the photothermal process induced by CO2 laser radiation and subsequently subjected to electrochemical treatment to fabricate a functional material with excellent conductivity and low charge-transfer resistance. Additionally, the laser-scribed electrodes presented a porous structure with graphene-like domains, thus indicating both potential for on-site electroanalytical applications and better performance than conventional carbon electrodes.
关键词： Graphene domains,Electrochemical sensors,Disposable devices,Porous material,Laser pyrolysis
更新于2025-09-12 10:27:22
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Non-enzymatic glucose sensors based on metal structures produced by laser-induced deposition from solution
摘要： The conditions for synthesis of conductive copper and nickel microstructures using laser-induced deposition technique were determined and electrocatalytic activity of these materials towards D-glucose was investigated. It was found out that formation of these conductive electrodes upon laser irradiation occurs only in solutions containing OH- coordinating ligands. Coordination via other functional groups (including carboxyl and amino) does not lead to synthesis of conductive structures. Topology and composition of copper and nickel deposits were observed using scanning electron microscopy and EDX analysis, respectively. The electrochemical properties of the synthesized structures were studied using cyclic voltamperometry and amperometry. The studied materials display linear dependencies of the Faraday current vs. concentration between 2 μM and 1.1 mM for nickel and 0.25 mM and 3 mM for copper.
关键词： Cyclic voltammetry,Nickel,Copper,Laser-induced deposition,Electrochemical sensors
更新于2025-09-12 10:27:22
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Nano- and Microfabrication for Industrial and Biomedical Applications || Chemical and biological sensors at component and?device level
摘要： Chemical and biological sensors were initially explored at the microscale as an extension of microchip technology. They have considerable advantages because of their rapid throughput, and the need for very small samples. The development of better and smaller photometric and fluorometric detectors has enabled optical absorbance systems to be produced on a chip. Electrochemical sensors measure the conductance of electrolytes in an aqueous sample, and can also measure concentrations of gases that diffuse into the sample. This makes them valuable as personal health care monitors. These systems have been applied in medical monitoring, and for monitoring and controlling industrial-scale reactions. The integrated chemFET device is an example of a real-world application of this technology, and measures pH. The device is based on the ion-sensitive field-effect transistor (ISFET), which is caused by ions in solution producing a current across a transistor. Changes in the pH produce a proportionate change in the signal. Biological material, including DNA and cells, can also be used as a sensor. Cells have been used to detect pathogens in food, by adhering them to a sensor’s surface by means of a polymer, and then detecting changes in their electrochemistry. DNA optical readout is a widely accepted method for analyzing DNA sequences.
关键词： pH measurement,Biological sensors,Microchip technology,Electrochemical sensors,Chemical sensors,ISFET,Cell-based biosensors,Optical sensors,DNA analysis
更新于2025-09-09 09:28:46