An enhanced electrochemiluminescence sensor modified with a Ru(bpy)32+/Yb2O3 nanoparticle/nafion composite for the analysis of methadone samples

Emerging trends and recent advances in MXene/MXene-based nanocomposites toward electrochemiluminescence sensing and biosensing

Electrochemiluminescence (ECL) sensing systems have surged in popularity in recent years, making significant strides in sensing and biosensing applications. The realization of high-throughput ECL sensors hinges on the implementation of novel signal amplification strategies, propelling the field toward a new era of ultrasensitive analysis. A key strategy for developing advanced ECL sensors and biosensors involves utilizing novel structures with remarkable properties. The past few years have witnessed the emergence of MXenes as a captivating class of 2D materials, with their unique properties leading to exploitation in diverse applications. This review provides a comprehensive summary of the latest advancements in MXene-modified materials specifically engineered for ECL sensing and biosensing applications. We thoroughly analyze the structure, surface functionalization, and intrinsic properties of MXenes that render them exceptionally suitable candidates for the development of highly sensitive ECL sensors and biosensors. Furthermore, this study explores the broad spectrum of applications of MXenes in ECL sensing, detailing their multifaceted roles in enhancing the performance and sensitivity of ECL (bio)sensors. By providing a comprehensive overview, this review is expected to promote progress in related areas.

How new nanotechnologies are changing the opioid analysis scenery? A comparison with classical analytical methods

Opioids such as heroin, fentanyl, raw opium, and morphine have become a serious threat to the world population in the recent past, due to their increasing use and abuse. The detection of these drugs in biological samples is usually carried out by spectroscopic and/or chromatographic techniques, but the need for quick, sensitive, selective, and low-cost new analytical tools has pushed the development of new methods based on selective nanosensors, able to meet these requirements. Modern sensors, which utilize "next-generation" technologies like nanotechnology, have revolutionized drug detection methods, due to easiness of use, their low cost, and their high sensitivity and reliability, allowing the detection of opioids at trace levels in raw, pharmaceutical, and biological samples (e.g. blood, urine, saliva, and other biological fluids). The peculiar characteristics of these sensors not only have allowed on-site analyses (in the field, at the crime scene, etc.) but also they are nowadays replacing the gold standard analytical methods in the laboratory, even if a proper method validation is still required. This paper reviews advances in the field of nanotechnology and nanosensors for the detection of commonly abused opioids both prescribed (i.e. codeine and morphine) and illegal narcotics (i.e. heroin and fentanyl analogues).

An electrochemiluminescence sensor based on the CNTs and CdSe@ZnSe for determination of melamine in milk samples

In this work, a novel electrochemiluminescence (ECL) sensor based on the CdSe@ZnSe and CNTs was constructed for the detection of melamine. CdSe@ZnSe acted as the co-reaction promoter for the enhancement of Ru(bpy)32+/tri-n-propylamine (TPrA) system and CNTs acted as carriers to immobilize more CdSe@ZnSe. The initial ECL signal significantly amplified due to the synergistic effect of CNTs and CdSe@ZnSe. The ECL signal decreased with the addition of melamine, and the change value of ECL intensity (ΔI) was linearly related to the logarithm of melamine concentration. The constructed ECL sensor was able to detect melamine in the range of 1.0 × 10-11 - 1.0 × 10-7 M, and the detection limit was 3.3 × 10-12 M (S/N = 3). It can be used to detect melamine in milk samples.

Biosensors based on functional nucleic acids and isothermal amplification techniques

In the past few years, with the in-depth research of functional nucleic acids and isothermal amplification techniques, their applications in the field of biosensing have attracted great interest. Since functional nucleic acids have excellent flexibility and convenience in their structural design, they have significant advantages as recognition elements in biosensing. At the same time, isothermal amplification techniques have higher amplification efficiency, so the combination of functional nucleic acids and isothermal amplification techniques can greatly promote the widespread application of biosensors. For the purpose of further improving the performance of biosensors, this review introduces several widely used functional nucleic acids and isothermal amplification techniques, as well as their classification, basic principles, application characteristics, and summarizes their important applications in the field of biosensing. We hope to provide some references for the design and construction of new tactics to enhance the detection sensitivity and detection range of biosensing.

An innovative fluorometric bioanalysis strategy towards recognition of DNA methylation using opto-active polymer: A new platform for DNA damage studies by genosensor technology

Efficient pharmacotherapy of cancer is related to accurate recognition of genetic mutations and epigenetic alterations in the early-stage diagnosis. In the present study, a novel optical genosensor based on toluidine blue as photonic probe was developed to detection of DNA methylation using hybridization of pDNA with cDNA. Biomedical analysis was performed using UV-vis and fluorometric methods. For the first time, this strategy was applied for the distinction of methylated DNA from unmethylated-DNA-based on the interaction of optical probe with methylated-DNA and unmethylated DNA. Fluorescence spectroscopic data showed that poly-toluidine blue could be bind to DNA sequences and lead to different fluorescence patterns and could be used as an efficient geno-platform for the sensitive bioassay of mutation. The excitation and emission wavelengths were 580 and 630 nm, respectively. Non-binding of mismatch sequences with the optical probe was used as negative control. Under optimal conditions, linear range was 1 zM to 0.2 pm and the lower limit of quantitation was obtained as target concentrations ranging 1 zM. The designed genosensor showed high capability to distinct methylation from un-methylated. Therefore, the designed DNA-based bioassay could detect DNA methylation significantly. Finally, bioanalysis of real samples showed that the designed genosensor could use to detect DNA methylation which is a new platform for point of care analysis.

Analytical Approaches for the Determination of Buprenorphine, Methadone and Their Metabolites in Biological Matrices

The abuse of buprenorphine and methadone has grown into a rising worldwide issue. After their consumption, buprenorphine, methadone and their metabolites can be found in the human organism. Due to the difficulty in the assessment of these compounds by routine drug screening, the importance of developing highly sensitive analytical approaches is undeniable. Liquid chromatography tandem mass spectrometry is the preferable technique for the determination of buprenorphine, methadone and their metabolites in biological matrices including urine, plasma, nails or oral fluids. This research aims to review a critical discussion of the latest trends for the monitoring of buprenorphine, methadone and their metabolites in various biological specimens.

Simultaneous electrochemical determination of morphine and methadone by using CMK-5 mesoporous carbon and multivariate calibration

For the first time, a sensitive electrochemical sensor using a glassy carbon electrode modified with CMK-5 Ordered mesoporous carbon was fabricated for simultaneous analysis of morphine and methadone. Modern electrochemical FFT-SWV techniques and partial least-squares as a multivariable analysis were used in this method. CMK-5 nanostructures were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and Raman spectroscopy. Variables such as accumulation time and pH for the proposed sensor were optimized before quantitative analysis. To train the proposed sensor, standard mixtures of morphine (MOR), and methadone (MET) were prepared in the established linear ranges of the analyzes. The results obtained from training samples were used for PLS modeling. The efficiency of the model was determined using test and real matrix samples. The root mean square error of prediction and the squared correlation coefficients (R²_p) for MET and MOR were estimated to be 0.00772 and 0.00892 and 0.948 to 0.990, respectively. The recoveries in urine samples were reported to be 97.0 and 105.6% for both MOR and MET, respectively.

Progress in pretreatment of methadone: an update since 2015

Methadone, a µ-opioid receptor agonist, is widely used in pain-relieving and treating opioid dependence. If not strictly controlled, as an opioid substitute, it can lead to abuse and cause more severe withdrawal responses than heroin. Also, overdose or abuse of this drug in clinical use may provide severe side effects such as apnea, circulatory collapse, cardiac arrest, and even death. For these reasons, simple, rapid, and efficient methods have been developed for the pretreatment of methadone. This review presents a comprehensive conclusion of the pretreatment methods used for methadone in various sample matrices, focusing on the developments since 2015. Traditionally used pretreatment methods like solid-phase extraction and liquid-liquid extraction are discussed and newly developed methods like solid-phase microextraction and liquid-liquid microextraction along with new materials applied are focused.

Ultrasound-assisted synthesis of two-dimensional layered ytterbium substituted molybdenum diselenide nanosheets with excellent electrocatalytic activity for the electrochemical detection of diphenylamine anti-scald agent in fruit extract

Metal chalcogenides with large active sites have been received great attention as an excellent catalyst due to their hierarchical structural properties. Here, we have demonstrated the synthesis of ytterbium-doped molybdenum selenide (YbMoSe₂) in the form of two-dimensional nanosheets by using a simple ultrasonic method. The formation of the crystal phase of prepared YbMoSe₂ nanosheets was studied by using the selective characterization techniques. The reported HRTEM confirmed that the introduction of heterogeneous spin of Yb with MoSe₂ creates the lattice distortion. Thus, the active sites can be increased by creating the lattice distortion on the basal plane of the metal chalcogenides nanosheets. The band gap study was carried out by using UV-visible spectrometer and demonstrated the decreasing band gap of MoSe₂ from 1.30 eV to 1.15 eV due to the Yb substitution/doping. The increasing active sites with decreasing band gap facilitate an excellent electronic conductivity and electrochemical activity. Furthermore, the electrocatalytic activity of YbMoSe₂ modified glassy carbon electrode (YbMoSe₂/GCE) toward the sensing of diphenylamine (DPA) anti-scald agent. As expected, YbMoSe₂/GCE showed a high level of electrochemical activity with a low limit of detection (0.004 µM) and excellent sensitivity (11.4 µA µM^-1 cm^-2) towards the detection of DPA. In addition, the superior selectivity, stability, and reproducibility of YbMoSe₂/GCE also were recorded. The beneficial electrochemical activity of YbMoSe₂/GCE offered the more advantages to detection of DPA in the food sample also.

Quenching Electrochemiluminescence Immunosensor Based on Resonance Energy Transfer between Ruthenium (II) Complex Incorporated in the UiO-67 Metal-Organic Framework and Gold Nanoparticles for Insulin Detection

This work describes a sandwich-type electrochemiluminescence (ECL) strategy for insulin detection by using Ru(bpy)₃²⁺ as the luminophore which was encapsulated in the UiO-67 metal-organic framework (UiO-67/Ru(bpy)₃²⁺). Because UiO-67 possesses the characteristics of large specific surface area and porosity, more Ru(bpy)₃²⁺ could be loaded onto its surface and holes, thus greatly improving the ECL efficiency. Furthermore, the ECL resonance energy transfer (ECL-RET) could occur between UiO-67/Ru(bpy)₃²⁺ (ECL donor) and Au@SiO₂ nanoparticles (ECL acceptor), resulting in a conspicuously decreased ECL response. The ECL spectrum of UiO-67/Ru(bpy)₃²⁺ which exhibited strong ECL intensity has suitable spectral overlap with the absorption spectrum of Au@SiO₂, which further proved the occurrence of the ECL-RET action. The ECL intensity decreased with the increase of the concentration of insulin. In addition, the sandwich-type ECL immunosensor was applied to insulin detection, and the ECL decrease efficiency was found to be logarithmically related to the concentration of the insulin antigen in the range of 0.0025 to 50 ng mL^-1 with the limit of detection of 0.001 ng mL^-1. Meanwhile, this work provides an important reference for the application of metal-organic frameworks in the ECL and ECL-RET study and also exhibits potential capability in the detection of other hormones.