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Auto-cleaning paper-based electrochemiluminescence biosensor coupled with binary catalysis of cubic Cu2O-Au and polyethyleneimine for quantification of Ni2+ and Hg2+
摘要： Inspired by the pop-up greeting cards, a 3D collapsible auto-cleaning paper-based electrochemiluminescence (ECL) biosensor (CAPEB) with different functions of signal collection and residual multiple cleaning, is developed for sensitive detection of Ni2+ and Hg2+ by simply regulating its 3D configurations. The multiple fluidic paths and the hollow-channel structure were firstly integrated into the paper substrate, realizing simultaneously repetitive auto-cleaning of the two working electrodes. For achieving ultrasensitive Ni2+ and Hg2+ monitoring, binary catalysis consisting of the intermolecular co-reaction (H2O2 and N-(4-Aminobutyl)-N-ethylisoluminol (ABEI)) and intramolecular catalysis (polyethyleneimine (PEI)-ABEI) were introduced. Specifically, silver nanospheres with a large specific surface area and excellent conductivity were grown on the paper working electrode and served as the sensor substrate for fixing PEI-ABEI and Ni2+-specific DNAzyme. With the assistance of DNAzyme, Cu2O-Au and ferrocene (Fc) labeled strand S2 were immobilized on electrode surface through the hybridization reaction, and catalyzed H2O2 to generate reactive oxygen species, promoting the luminescence of ABEI. In the existence of Ni2+, DNAzyme was activated followed by cleavage of strand S2 to induce the release of Fc, which quenched the ECL signal of ABEI, eventually realizing the detection of Ni2+. Similarly, for sensitive quantification of Hg2+, full thymine (T) bases strand S3 was modified on surface of Cu2O-Au and anchored Hg2+ by T-Hg2+-T pairing interaction. The ECL intensity was decreased along with increasing of Hg2+ due to the quenching effect of Hg2+ on ECL emission of ABEI. Based on this ingenious system, the detection of Ni2+ and Hg2+ had high sensitivity, wide linear ranges, and low detection limits. The results indicated that the integration of a multi-channel structure into a paper device chips opened new opportunities for designing promising paper-based devices for metal ions diagnosis.
关键词： electrochemiluminescence,N-(4-Aminobutyl)-N-ethylisoluminol,auto-cleaning,Cu2O-Au,paper-based device,heavy metal ion
更新于2025-09-23 15:21:01
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Optical fiber sensors for measurement of heavy metal ion concentration: A review
摘要： With the increasing of water pollution problems, detection of heavy metal ion concentration in water environment becomes significant. Optical fiber sensor, with its particular advantages of small-size, anti-electromagnetic interference, chemical inertness, remote and real-time monitoring ability, has become an ideal platform for detection of heavy metal ion concentration. In this paper, we briefly review the current research progress of heavy metal ion sensors based on optical fiber technology. Five main measurement methods are described, including optical absorbance method, fiber grating method, modal interference method, plasmonic method, and fluorescence method. The sensing mechanisms, sensing structures, sensing materials, and sensing characteristics of different kinds of measurement methods are introduced and summarized. Furthermore, the advantages and disadvantages of each measurement method are analyzed. Finally, the future development directions of optical fiber heavy metal ion sensors are also discussed.
关键词： Water pollution,Optical fiber sensor,Concentration measurement,Heavy metal ion sensor
更新于2025-09-23 15:19:57
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Fluorescence Characteristics of Aqueous Synthesized Tin Oxide Quantum Dots for the Detection of Heavy Metal Ions in Contaminated Water
摘要： Tin oxide quantum dots were synthesized in aqueous solution via a simple hydrolysis and oxidation process. The morphology observation showed that the quantum dots had an average grain size of 2.23 nm. The rutile phase SnO2 was confirmed by the structural and compositional characterization. The fluorescence spectroscopy of quantum dots was used to detect the heavy metal ions of Cd2+, Fe3+, Ni2+ and Pb2+, which caused the quenching effect of photoluminescence. The quantum dots showed the response of 2.48 to 100 ppm Ni2+. The prepared SnO2 quantum dots exhibited prospective in the detection of heavy metal ions in contaminated water, including deionized water, deionized water with Fe3+, reclaimed water and sea water. The limit of detection was as low as 0.01 ppm for Ni2+ detection. The first principle calculation based on the density function theory demonstrated the dependence of fluorescence response on the adsorption energy of heavy metal ions as well as ion radius. The mechanism of fluorescence response was discussed based on the interaction between Sn vacancies and Ni2+ ions. A linear correlation of fluorescence emission intensity against Ni2+ concentration was obtained in the logarithmic coordinates. The density of active Sn vacancies was the crucial factor that determined fluorescence response of SnO2 QDs to heavy metal ions.
关键词： heavy metal ion,tin oxide,fluorescence,quantum dot,sensing mechanism,water pollution
更新于2025-09-11 14:15:04
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Microalgae biochar-derived carbon dots and their application in heavy metal sensing in aqueous systems
摘要： This research seeks a coupled solution for managing the large amounts of biochar produced by microalgae biofuel production, and the necessity for novel, economic and accurate heavy metal sensing methods. Therefore, this study evaluated the transformation of microalgae biochar (MAB) into carbon dots (Cdots) and their subsequent application as heavy metal ion sensors in aqueous systems. The experimental phase included the transformation of MAB into microalgae biochar-derived carbon dots (MAB–Cdots), MAB–Cdot characterisation and the evaluation of the MAB–Cdots as transducers for the detection of four heavy metal ions (Pb2+, Cu2+, Cd2+, and Ni2+). MAB–Cdot fluorescence was stable over a wide range of pH and resistant to photo-bleaching, making them suitable as fluorescence probes. The MAB–Cdot fluorescence was quenched by all of the metal ions and displayed different quenching levels. Depending upon the ions involved, MAB–Cdots were used to detect the presence of heavy metal ions from concentrations of 0.012 μM up to 2 mM by measuring the reduction in fluorescence intensity. Neutral and slightly alkaline pHs were optimal for Cu2+ Ni2+ and Pb2+ heavy metal quenching. To quantify the concentration of the heavy metal ions, linear and logarithmic functions were used to model the MAB–Cdot fluorescence quenching. The sensing mechanism was determined to be reversible and purely collisional with some fluorophores less accessible than the others. This work demonstrated the ability to produce Cdots from microalgae biochar, examined their application as a transducer for detecting heavy metal ions in aqueous systems and paves the way for novel sensing systems using MAB-Cdots.
关键词： Heavy metal ion,Carbon dots,Renewable nanomaterials,Quenching,Biochar,Microalgae,Fluorescence sensors
更新于2025-09-09 09:28:46
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[IEEE 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Greifswald, Germany (2018.9.23-2018.9.28)] 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Advanced Vacuum Arc Plasma Source: Principles and Perspective Applications
摘要： A combined system including a MEVVA plasma source with a cylindrical electrostatic plasma-optical lens is considered for the first time. This combined system is of fundamental interest and could be attractive for a number of practical applications. The system can be used for effective repetitively pulsed, high current, moderate energy plasma sources of heavy metal ions and electrons. The hardware is interesting for high productivity technological equipment using dense pure plasma flow for the synthesis of fine coatings and thin films. We have studied the plasma-dynamic characteristics of high density plasma flow propagating through the plasma lens, the optical emission spectra and the charge state distribution, as a function of different experimental conditions. Application of the plasma lens to the transport of low energy high-current ion beams can improve the delivery of plasma to a substrate, as well as providing micro-droplet evaporation and elimination due to the presence of fast electrons within the lens region.
关键词： plasma-optical lens,vacuum arc,heavy metal ion source,plasmadynamics
更新于2025-09-09 09:28:46