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•A ratiometric fluorescent probe was designed for detecting ciprofloxacin (CIPRO).•The mechanism was based on La3+-enhanced fluorescence of GSH@AuNCs.•The probe displayed outstanding ...detection stability due to ratiometric response.•The probe also possessed the features of fast response and excellent sensitivity.•The probe was successfully applied to the determination of CIP in human urine and milk samples.
In this research work, ultrasensitive and reliable ratiometric sensor was designed for assay of ciprofloxacin (CIPRO). The platform consists of thiolate-protected gold nanoclusters (GSH@AuNCs) with high fluorescence quantum yield and long-term stability. In the existence of lanthanum (La3+) ion, the GSH@AuNCs emission was sharply raised owing to the formation of La3+/GSH@AuNCs system accompanied with aggregation-induced emission enhancement (AIEE). Addition of CIPRO, a good La3+ ion coordinator, decreased the fluorescence emission of La3+/GSH@AuNCs system at 610 nm significantly as a result of disaggregation caused by the removal of La3+ ion from GSH@AuNCs surface. Furthermore, the blue emission of La3+-CIPRO coordination complex appears at 440 nm. Under optimized conditions, the fluorescence ratios (F440/F610) were linearly increased with increasing the CIPRO amount within the range of 0.003–200 µM with a limit of detection equal to 0.2 nM (S/N = 3). The as-fabricated La3+/GSH@AuNCs system possesses outstanding reliability and sensitivity for the detection of CIPRO. The system was effectively used to assay CIPRO in human urine and milk specimens with recoveries % of 97.6–102.3 % and 96.7–105.7 % for urine and milk samples, respectively and RSD % did not exceed 2.5 %, suggesting the accuracy of the method.
Unmanned Aerial Vehicles (UAVs) are considered an important element in wireless communication networks due to their agility, mobility, and ability to be deployed as mobile base stations (BSs) in the ...network to improve the communication quality and coverage area. UAVs can be used to provide communication services for ground users in different scenarios, such as transportation systems, disaster situations, emergency cases, and surveillance. However, covering a specific area under a dynamic environment for a long time using UAV technology is quite challenging due to its limited energy resources, short communication range, and flying regulations and rules. Hence, a distributed solution is needed to overcome these limitations and to handle the interactions among UAVs, which leads to a large state space. In this paper, we introduced a novel distributed control solution to place a group of UAVs in the candidate area in order to improve the coverage score with minimum energy consumption and a high fairness value. The new algorithm is called the state-based game with actor-critic (SBG-AC). To simplify the complex interactions in the problem, we model SBG-AC using a state-based potential game. Then, we merge SBG-AC with an actor-critic algorithm to assure the convergence of the model, to control each UAV in a distributed way, and to have learning capabilities in case of dynamic environments. Simulation results show that the SBG-AC outperforms the distributed DRL and the DRL-EC3 in terms of fairness, coverage score, and energy consumption.
Carbon paste electrode (CPE) modified with porous copper based metal organic framework (Cu-MOF) nanocomposite is described for analysis of cyanide (CN−) for the first time. The electrochemical ...performance of the proposed electrode was investigated by differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The Cu-MOF nanocomposite was characterized using scanning electron microscope (SEM), N2-adsorption-desorption isotherms, powder X-ray powder diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Under optimal conditions of measurements, the anodic peak (Ipa) decreases linearly in the range of 1.87–25 μM with LOD of 0.60 μM (at S/N = 3). The Cu-MOF/CPE showed good selectivity towards CN− measurement with no significant interference in pH 7.0 using 0.25 M KCl to increase the medium conductivity and to stabilize the analyte and prevents its volatility. Moreover, the method was successfully applied for determination of CN− in different environmental water samples.
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•A new electrochemical sensor was proposed for analysis of cyanide (CN−) for the first time.•The electrochemical sensor is a porous copper metal organic framework (Cu-MOF) modified carbon paste electrode.•The mechanism of detection based on decreasing the peak currents of Cu-MOF by the target analyte CN−.•The sensor exhibits good sensitivity, stability, reproducibility, and sufficient selectivity towards CN−.•The proposed sensor was used to detect CN− in different water samples with satisfactory results.
An ultrasensitive dual-signal ratiometric electrochemical sensor was developed for creatinine detection utilizing silver nanoparticles (Ag) with intrinsic self-calibration afforded by iron-nickel ...bimetallic Prussian blue (FeNiPBA) analogues. The Ag@FeNiPBA exhibits two redox signals corresponding to the Ag
+
/Ag and Fe
3+
/Fe
2+
systems. Adding chloride (Cl
−
) solution increases the anodic current of the Ag/Ag system significantly due to the formation of silver chloride through solid-state electrochemistry. While the anodic current of the Ag/Ag system decreases in the presence of creatinine due to the competitive reaction, the Fe/Fe system's anodic current remains the same, which enables a ratiometric response. Under optimized conditions, the response ratio (I
Ag
/I
Fe
) decreases while the creatinine concentration increases linearly between 0.015 and 140 μM, with 0.004 μM as a good detection limit (S/N = 3). These results demonstrate superior performance over previously reported methods for electrochemical creatinine determination. The high sensitivity arises from the signal amplification of the Ag/AgCl solid-state electrochemistry, while the selectivity originates from the specific interaction between Ag
+
and creatinine. The Ag@FeNiPBA hybrid can quantify creatinine in real samples with good recoveries. This work opens up new opportunities for applying dual-signal nanostructures to develop electrochemical sensors for (bio)molecule detection.
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•AuNPs@Cu-MOF was synthesized by a facile method.•It shows a good electro-catalytic activity towards D-PA determination.•D-PA is detected by the formation of complex at low ...potential.•The modified sensor shows wide linear range and low LOD.•The sensor was efficiently applied for capsules, plasma and urine samples.
Copper based-metal organic frameworks modified with gold nanoparticles (AuNPs@Cu-MOF) was fabricated via facile approach. The nanocomposite was used to decorate glassy carbon electrode (GCE) for the electrochemical sensing of D- penicillamine (D-PA). The nanocomposite was characterized using different techniques such as scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray spectroscopy (PXRD), thermogravimetry (TGA), nitrogen adsorption–desorption isotherms, and Fourier Transform infrared spectroscopy (FTIR). Formation of a new anodic peak of Cu(II)-D-PA complex at + 0.38 V was used to detect D-PA. Cyclic and square wave voltammetric studies proved that AuNPs elevated the conductivity of Cu-MOF. The sensor exhibited wide linear range (0.4–75 × 10−7 M) and low detection limit (0.11 × 10−7 M) with a good sensitivity (0.9 ± 0.01 μA/μM). It was successfully applied for the estimation of D-PA in different real samples with recoveries % and relative standard deviations % (RSDs %) in the range of 95.6–102.5% and 2.4–3.3%, respectively.
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•A novel DA fluorescent probe was developed using β-CD/N@GQDs modified with PYL.•Upon addition of PYL, the yellow emission of probe was decreased.•Attachment of DA to PYL/β-CD@ N@GQDs ...enhances the blue emission at 420 nm.•Using the fluorescent probe, DA can be detected down to 0.117 nM.•The fluorescent probe shows high selectivity towards DA detection.
Herein, a novel and rapid fluorometric nanoprobe was constructed for quantitation of dopamine (DA) in presence of biologically interfering compounds. The nanoprobe based on synthesis of yellow emissive nitrogen doped graphene quantum dots (N@GQDs) by advanced thermal driven oxidation. After that, the synthesized N@GQDs was capped with β-cyclodextrin (β-CD), followed by interaction with pyridoxal (PYL) vitamin B6 cofactor. This interaction resulted in diminishing the yellow fluorescence of β-CD/N@GQDs, and appearance of blue emission peak at 420 nm. Upon addition of DA, the blue emission of β-CD/N@GQDs was increased after excitation at λ = 330 nm. Under optimum conditions, the nanoprobe exhibited a linear range of 0.36–400 nM with limit of detection (LOD) of 0.117 nM. In addition, the fluorescent nanoprobe shows high selectivity and can be used for detection of DA in complicated biological matrices and human serum. This strategy might provide a potential tool for clinical diagnosis and biomedical research for DA related diseases.
An innovative electrochemical nanoprobe, for analysis of salinomycin (SAL), was proposed. The nanoprobe based on decoration of glassy carbon electrode (GCE) with 3D rose like La3+@ ZrO2 supported on ...reduced graphene oxide (RGO) nanosheets. The 3D rose like La3+@ ZrO2 was synthesized via sintering process. The successful decoration of 3D rose like La3+@ ZrO2 on the surface of RGO was characterized using different spectroscopic and analytical techniques. The obtained voltammetric results confirmed the good electrochemical performance of 3D rose like La3+@ ZrO2 in terms of lower peak potential (Epc) and higher cathodic current (Ipc). Moreover, the modified nanoprobe showed wide linearity range (0.34–115 × 10−8 M), lower detection limit (0.11 × 10−8 M) and higher selectivity. Besides, the nanocomposite showed good applicability for analysis of SAL in biological fluids and during pharmacokinetic evaluation in rabbit plasma. The obtained results opens a new venue for the determination of futuristic drug, SAL, during pharmacokinetic and pharmacodynamics studies.
•3D like La3+@ZrO2 was prepared by facile hydrothermal co-precipitation method.•Reduced graphene oxide (RGO) was used as supporter and a signal amplifier.•3D like La3+@ZrO2 NFs/RGO is efficient electro-catalyst for salinomycin (SAL).•The proposed sensor exhibited good sensitivity, reproducibility, stability and selectivity towards SAL analysis.•The proposed sensor shows good applicability towards SAL and during pharmacokinetic evaluation.
Herein, a novel and rapid fluorometric nanoprobe was constructed for quantitation of dopamine (DA) in presence of biologically interfering compounds. The nanoprobe based on synthesis of yellow ...emissive nitrogen doped graphene quantum dots (N@GQDs) by advanced thermal driven oxidation. After that, the synthesized N@GQDs was capped with β-cyclodextrin (β-CD), followed by interaction with pyridoxal (PYL) vitamin B
cofactor. This interaction resulted in diminishing the yellow fluorescence of β-CD/N@GQDs, and appearance of blue emission peak at 420 nm. Upon addition of DA, the blue emission of β-CD/N@GQDs was increased after excitation at λ = 330 nm. Under optimum conditions, the nanoprobe exhibited a linear range of 0.36-400 nM with limit of detection (LOD) of 0.117 nM. In addition, the fluorescent nanoprobe shows high selectivity and can be used for detection of DA in complicated biological matrices and human serum. This strategy might provide a potential tool for clinical diagnosis and biomedical research for DA related diseases.
Herein, a novel “ON-OFF” colorimetric and fluorometric chemosensor; 1N-allyl-2-(2, 5-dimethoxyphenyl)-4, 5-diphenyl-1H-imidazole (ADPPI), was constructed for sequential determination of Cu2+ and S2− ...ions in aqueous media. The interaction between chemosensor ADPPI and different metal cations was investigated using UV-VIS and fluorimetric spectroscopy. ADPPI showed a favorable and good interaction with Cu2+ ions producing blue colored solution peaked at 610 nm with blue fluorescence at λem. = 447 nm. The produced complex between Cu2+ ions and ADPPI can be used as a cascade probe for detection of S2− ions. The detection limits (LODs) were 1.01 nM and 1.25 μM for Cu2+ and S2− ions, respectively (the lowest between the family of colorimetric and fluorometric chemosensors). To further increase the applicability of the proposed method, Cu2+ and S2− ions concentrations were measured in environmental water samples.
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•An imidazole derived colorimetric and fluorometric chemosensor has been developed for rapid detection of Cu2+ and S2-.•The chemosensor exhibited binding-induced color changes from colorless to blue.•The formed L-Cu2+ complex has been used as a new cascade sensor for detecting S2-.•The chemosensor shows good sensitivity and selectivity.•The method was applied efficiently for analysis of Cu2+ and S2- in environmental water samples with high selectivity.
Herein, a rational combination of dispersive solid-phase sorbent and 2-(2, 4-Dihydroxyphenyl)-3, 5, 7-trihydroxychromen-4-one (morin) was proposed for sensitive and selective determination of Al3+ ...ion. Nickel ferrite nanospheres (NiFe2O4 NS) functionalized with morin was used to preconcentrate and estimate Al3+ via the formation of fluorescent complex at pH 7.0. The functionalization was assisted by anionic surfactant sodium dodecyl sulphate (SDS) and ultrasonication. The results revealed that the fluorescence intensity of Al-morin/SDS@ NiFe2O4 NS is higher than Al-morin. Functionalization of NiFe2O4 NS with morin was confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffractometer (PXRD), and fluorescence spectroscopy. Under the optimum conditions, the fluorescence intensity increased with increasing of Al3+ concentrations in the range of 0.28–500.0 ng mL−1 with LOD (S/N = 3) of 0.09 ng mL−1. The method was applied for the determination of Al3+ in natural waters and human serum samples with recoveries % of 97–104% and RSDs % of 2–4%.
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•Rationale combination of NiFe2O4 NS and morin was proposed.•Combination was aided by anionic surfactant SDS and ultrasonication.•It was used for solid-phase microextraction of Al3+ ion.•The method exhibits simplicity, sensitivity and reliability.•It was used to estimate Al3+ ion in natural waters and blood serum samples.
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