Microcystin-LR (MC-LR) is a kind of hepatotoxin which can cause functional and structural disturbances of the liver, accumulate in aquatic organisms and transfer to higher trophic levels, a ...biocompatible electrochemical immunosensor was constructed to detect MC-LR sensitively and selectively. The three-dimensional villiform-like carbon nanotube/cobalt silicate (CNT@Co silicate) core–shell nanocomposites were synthesized and firstly used as the substrate to immobilize the antigen of MC-LR (Ag), while Fe3O4 nanoclusters/polydopamine/gold nanoparticles (Fe3O4@PDA–Au) core–shell magnetic nanocomposites were prepared as the label carrier of the immunosensor to conjugate the second antibody (Ab2) and horse radish peroxidase (HRP). Since the toxicity of nanomaterials is important in the construction of biosensors including the immobilization of antigen or antibody, the biocompatibility of such nanocomposites were investigated by monitoring the cell viability after culturing with Hela cells. Due to the excellent biocompatibility, the immunosensor can immobilize more antigens by the large surface area of the three-dimensional villiform-like structure in CNT@Co silicate, and provide high electrochemical signals by Fe3O4@PDA–Au labeled Ab2 and HRP. After investigation of the binding capability of biomolecules on nanomaterials and optimization of the conditions in the competitive immunoassay, the proposed electrochemical immunosensor shows a linear response to MC-LR in the range from 0.005μg/L to 50μg/L with a detection limit of 0.004μg/L. In addition, the specificity, reproducibility and stability of the immunosensor were also proved to be acceptable, indicating its potential application in environmental monitoring.
•Fe3O4@PDA–Au was prepared and regulated with a simple and in-situ reduction.•The biocompatibility of nanomaterials was studied by the cytotoxicity experiments.•The loading concentration of HRP and Ab2 on nanomaterials was investigated.•Core–shell nanostructures sensitized immunosensor was constructed for microcystin-LR detection.
The enantioselective detection of trace amounts of ofloxacin is very important in many fields. In this work, an enantioselective and sensitive electrochemical immunosensor was constructed for the ...detection of chiral antibiotic ofloxacin based on a dual amplification strategy using multiwall carbon nanotubes-poly(l-lysine) as a matrix to immobilize the antigen and multi-enzyme-antibody functionalized gold nanoflowers as an electrochemical detection label. The fabrication process of the dual-amplified immunosensor was characterized by scanning electron microscopy, cyclic voltammogram and electrochemical impedance spectroscopy, respectively. After the optimization of the experimental conditions, a competitive immunoassay, i.e., the association ability with the corresponding antibody between the captured antigen and free S-OFL or R-OFL in the solution, showed that the immunosensor exhibited a sensitive response to S-OFL in the range from 0.26 to 25.6ng/mL with a detection limit of 0.15ng/mL as well as a sensitive response to R-OFL in the range from 0.37 to 12.8ng/mL with a detection limit of 0.30ng/mL. Along with the acceptable sensitivity and stability, the S-OFL or R-OFL immunosensor showed selective ability to its corresponding enantiomer, suggesting this amplification strategy may hold a potential application in the detection of OFL in food or environment.
•Biocompatible MWCNT–PLL composites were synthesized to immobilize antigen.•Multi-enzyme-labeled gold nanoflowers were used to amplify the electrochemical signal.•A sensitive immunosensor was fabricated for the enantioselective detection of ofloxacin.
A broad-specific photoelectrochemical (PEC) immunosensor was developed for the simultaneous detection of ochratoxin A, ochratoxin B and ochratoxin C (OTA, OTB, OTC) by using the direct growth of CdS ...nanorods on FTO as the photoelectrode and Au nanoflowers-modified glass carbon electrode (GCE) as the bioelectrode. The bioelectrode was used to capture antigens and then associate corresponding antibodies, followed by using SiO2@Cu2+ nanocomposites to conjugate the secondary antibody (Ab2) and a DNA strand as the initiator. After the hybridization chain reaction (HCR) and the addition of hemin, numerous DNAzymes (G-quadruplex/hemin) were produced. Due to the similar enzymatic property with horseradish peroxidase (HRP), G-quadruplex/hemin can accelerate the oxidation of 4-chloro-1-naphthol (4-CN) with H2O2 to yield the biocatalytic precipitation (BCP) on the bioelectrode. Then, the bioelectrode was further treated with moderate acid and thus Cu2+ was released, which can decrease the photocurrent of the photoelectrode by the formation of CuS. Due to the advantages of surface effect of Au nanoflowers, DNA amplification and high photoelectrocatalytic activity, the proposed broad-specificity PEC immunosensor can detect OTA, OTB and OTC with a detection limit of 0.02, 0.04 and 0.03 pg/mL, respectively. In addition, the acceptable stability and selectivity suggest its possible application in the detection of OTA, OTB and OTC in water samples.
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•A broad-specific PEC immunosensor was developed to detect OTA, OTB and OTC simultaneously.•Separate electrodes including photoelectrode and bioelectrode were used in the immunosensor.•Au nanoflowers were modified on glassy carbon electrode to immobilize antigens.•Ab2-SiO2@Cu2+-S0 was prepared as the label to form G-rich DNA sequences by HCR.•The release of Cu2+ can further increase the current change by the formation of CuS.
Three kinds of immunochromatographic assays (ICAs) are proposed for the highly sensitive and rapid determination of tylosin (TYL) and tilmicosin (TIM) in eggs based on colloidal gold (CG), latex ...microsphere (LM), and time-resolved fluorescent microsphere (TRFM). Three types of ICAs could tolerate the egg matrix via simple sample pretreatment and demonstrated high sensitivity for TYL and TIM with cut-off values of 6/6/3 μg/kg and 14/14/6 μg/kg, respectively. Furthermore, in a single-blind parallel study 20 egg samples were analyzed by the three developed ICAs and confirmed by LC–MS/MS. The results showed good consistency, and there were no false positive and false negative results in our three ICAs. Consequently, the proposed three ICAs offered rapid, highly sensitive, reliable, and selectable testing platforms for screening veterinary medicine or other small molecule contaminants.
Graphic Abstract
The capacitated vehicle routing problem with stochastic demands and time windows is an extension of the capacitated vehicle routing problem with stochastic demands, in which demands are stochastic ...and a time window is imposed on each vertex. A vertex failure occurring when the realized demand exceeds the vehicle capacity may trigger a chain reaction of failures on the remaining vertices in the same route, as a result of time windows. This paper models this problem as a stochastic program with recourse, and proposes an adaptive large neighborhood search heuristic for its solution. Modified Solomon benchmark instances are used in the experiments. Computational results clearly show the superiority of the proposed heuristic over an alternative solution approach.
With the aggravation and evolution of global warming, natural disasters such as hurricanes occur more frequently, posing a great challenge to large-scale power systems. Therefore, the pre-position ...and reconfiguration of the microgrid defense resources by means of Mobile Energy Storage Vehicles (MEVs) and tie lines in damaged scenarios have attracted more and more attention. This paper proposes a novel two-stage optimization model with the consideration of MEVs and tie lines to minimize the shed loads and the outage duration of loads according to their proportional priorities. In the first stage, tie lines addition and MEVs pre-position are decided prior to a natural disaster; in the second stage, the switches of tie lines and original lines are operated and MEVs are allocated from staging locations to allocation nodes according to the specific damaged scenarios after the natural disaster strikes. The proposed load restoration method exploits the benefits of MEVs and ties lines by microgrid formation to pick up more critical loads. The progressive hedging algorithm is employed to solve the proposed scenario-based two-stage stochastic optimization problem. Finally, the effectiveness and superiority of the proposed model and applied algorithm are validated on an IEEE 33-bus test case.
•Separate electrodes including photoelectrode and bioelectrode were used in the immunosensor.•CdS/B-TiO2 nanorods with high photocurrent in the visible region was ...prepared.•Ab2-SiO2@G-quadruplex/hemin was prepared to accelerate the formation of BCP on the electrode.•A photoelectrochemical immunosensor was developed to detect MC-LR sensitively.
A photoelectrochemical immunosensor was developed for the sensitive detection of microcystin-LR (MC-LR) by using the Au nanoclusters as the substrate and silica-functionalized DNAzyme concatamers as the label carrier. The branched TiO2 nanorods (B-TiO2 NRs) decorated with CdS nanoparticles were modified on FTO and acted as the photoelectrode, while the bioelectrode was prepared by in-situ electrodepositing Au nanoclusters on dopamine-modified glassy carbon electrode (GCE) to immobilize antigen. Then, silica nanospheres with excellent monodispersity were used to conjugate the secondary antibody and G-quadruplex/hemin, which can accelerate the oxidation of 4-chloro-1-naphthol (4-CN) with H2O2 to yield the biocatalytic precipitation (BCP) on the electrode. Thus, the photoelectrocatalytic activity of the CdS/B-TiO2 NRs photoelectrode can be greatly retarded. By taking the advantages of surface effect of Au nanoclusters, DNA amplification and high photoelectrocatalytic activity, the proposed photoelectrochemical immunosensor can detect MC-LR in a wide range of 0.001–100μg/L with a detection limit of 0.7ng/L. In addition, the acceptable stability and selectivity suggested its possible application in the detection of MC-LR in water samples.
An ultrasensitive photoelectrochemical (PEC) immunoassay based on multiple signal amplification strategy was fabricated for the detection of microcystin-LR (MC-LR). The CdS/TiO2 nanorod arrays ...(CdS/TiO2 NRAs) modified FTO electrode, which can weaken the self-oxidation by photogenerated holes of CdS nanoparticles, and limit the recombination of electron-hole pairs and broaden optical absorption of TiO2 NRAs, was used as a visible-light driven material to immobilize antigens. Then, Fe3O4 nanoparticles/polydopamine (Fe3O4@PDA) was used as the carrier to load secondary antibody (Ab2) and horseradish peroxidase (HRP), where Fe3O4 nanoparticles and HRP can synergistically accelerate the oxidation of 4-chloro-1-naphthol (4-CN) by H2O2 to produce biocatalytic precipitation (BCP) on the surface of modified electrode. Due to the catalytic activity of Fe3O4 nanoparticles and HRP, the nonproductive absorption of HRP and the steric hindrance by BCP, the photocurrent change was amplified. The proposed PEC immunosensor can detect MC-LR in a range of 0.005–500 μg/L with a detection limit of 0.001 μg/L. Meanwhile, the PEC immunosensor exhibited high sensitivity, good stability, acceptable selectivity and reproducibility, indicating its potential application in environmental monitoring.
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•In-situ generation of CdS on TiO2 NRAs with high photo-to-current conversion efficiency was used.•Fe3O4@PDA conjugate was used as the label carrier to immobilize Ab2 and HRP.•Fe3O4 NPs and HRP can synergistically accelerate the oxidation of 4-CN to produce BCP.•An ultrasensitive PEC immunosensor was constructed for MC-LR detection.
•A portable and wireless point-of-need detection system for microcystin-LR (MC-LR) quantitation was developed and validated.•The detection system consisted of three main parts: screen printed carbon ...electrodes (SPCEs), smartphone-controlled electrochemical analyzer (SCEA), and Android's smartphone.•A spatiotemporal mapping of MC-LR field detection was conducted to further validate the feasibility of the SCEA for on-site screening.
The development of rapid and in situ detection method for microcystin-LR (MC-LR) with portable, reliable, and easy to use devices are highly demanded, but it is still deficient. In this study, a portable and wireless point-of-need detection system for microcystin-LR (MC-LR) quantitation was developed and validated. The whole system consisted of three main parts: screen printed carbon electrodes (SPCEs), smartphone-controlled electrochemical analyzer (SCEA), and Android's smartphone. The SCEA was a homemade ARM STM32 microcontroller-based electrochemical analyzer, which have similar performance compared with a commercially available electrochemical workstation. A smartphone installed with a user-friendly application was employed to control the analyzer, receive and analyze data, and display detection results in real-time. This system can accurately quantitate MC-LR in the range of 0.001–100 μg/L with a detection limit of 0.00011 μg/L, and the results were consistent with LC–MS/MS. In addition, a preliminary MC-LR contamination map was generated using this smartphone-based platform by measuring water samples at 6 reservoirs located in Pearl River Delta (Guangdong Province, China). The cost-effective, reliable and easy-to-use smartphone-based detection system reported here can facilitate active toxicant screening to guarantee the safety of the drinking water, particularly in resource-limited area.
In recent years, renewable energy has seen widespread application. However, due to its intermittent nature, there is a need to develop energy management systems for its scheduling and control. This ...paper introduces a multi-stage constraint-handling multi-objective optimization method tailored for resilient microgrid energy management. The microgrid encompasses diesel generators, energy storage systems, renewable energy sources, and various load types. The intelligent management of generators, batteries, switchable loads, and controllable loads ensures a reliable power supply for the critical loads. Beyond operational costs, our model also considers grid dependency as a key objective, making it particularly suited for energy management in extreme environments such as islands, border regions, and military bases. Managing complex controls of generators, batteries, switchable loads, and controllable loads presents challenging constraints that the management strategy must meet. To tackle this challenge, we propose an multi-objective optimization algorithm with multi-stage constraint-handling strategy to handle the high-dimensional complex constraints of the resilient energy management problem. Our proposed approach demonstrates superior performance compared to nine leading constrained multi-objective optimization algorithms across various test scenarios. Furthermore, the benefits of our method become increasingly evident as the complexity of the problem increases. Compared to the classical NSGA-II, the proposed NSGA-II-MC method achieved a 49.7% improvement in the Hypervolume metric on large-scale problems.
