Sensors & diagnostics最新文献

Contact lenses offer a simple, cost-effective, and non-invasive method for in situ real-time analysis of various biomarkers. Electro-chemical sensors are integrated into contact lenses for analysis of various biomarkers. However, they suffer from rigid electronic components and connections, leading to eye irritation and biomarker concentration deviation. Here, a flexible and microfluidic integrated paper-based contact lens for colorimetric analysis of glucose was implemented. Facilitating a three-dimensional (3D) printer for lens fabrication eliminates cumbersome cleanroom processes and provides a simple, batch compatible process. Due to the capillary force of the filter paper, the sample was routed to detection chambers inside microchannels, and it allowed further colorimetric detection. The paper-embedded microfluidic contact lens successfully detects glucose down to 2 mM within ∼10 s. The small dimension of the microfluidic system enables detection of glucose levels as low as 5 μl. The results show the potential of the presented approach to analyze glucose concentration in a rapid manner. It is demonstrated that the fabricated contact lens can successfully detect glucose levels of diabetic patients.

Dual state emission luminogens (DSEgens) with strong fluorescence in both solution and solid states have extensive potential for numerous applications. Herein, a chroman-2,4-dione and indoline conjugate, 2, was synthesized for highly selective and sensitive turn-on fluorescent detection of cyanide ions. Compound 2 behaves as a molecular rotor and shows the dual state emission (DSE) phenomenon and multicolour emission. It displays bright fluorescence in both the concentrated solution and the solid-state. The compound is nonfluorescent in dilute solution, and with increasing concentration, it shows aggregation caused red-shifted emission. With increasing concentration, the emission colour changes from green to yellow to orange-red. The CC bond attached to the indoline moiety is a compelling target for nucleophilic addition. Cyanide ions reacted with the probe which remarkably changed the spectroscopic properties. With the gradual addition of cyanide, the colour of the probe solution was changed from yellow to colorless. The very weakly emissive probe 2 rapidly reacted with CN⁻ and emitted strongly due to the inhibition of internal charge transfer (ICT) from indoline to chroman-2,4-dione. The DSEgen properties and CN sensing were thoroughly investigated and supported using spectroscopic studies, TDDFT, and single-crystal X-ray diffraction.

Surface-engineered conducting polymers (CPs) have enabled technological advances in chemistry and materials science. Heterocyclic conjugated organic molecules, specifically indole and its derivatives, have the potential to be polymerized under electrochemically controlled conditions in different types of compatible solvent media, including self-assembled nanofluids, for several applications. Polymer-based electrode materials are valuable for the detection of various targeted biomolecules and other analytes. This review outlines the evolution of the electropolymerization technique in recent years, along with developments in the field. With advances in nanoscience, several materials have been used to modify CPs for electrochemical sensing. Several biomedical applications and the role of antifouling agents in the properties of several electropolymerized thin films are highlighted.

Malignant tumors are the second leading cause of human deaths worldwide, and early cancer screening and diagnosis can effectively reduce cancer mortality. Herein, we propose a new electrochemical method for the highly sensitive detection of MUC1-positive tumor cells based on proximity labelling-assisted multiple signal amplification. Specifically, a MUC1 aptamer-modified electrode was prepared for capturing MUC1-positive tumor cells, followed by binding of G4-DNA strands to the cells with the aid of a mild reduction reaction. A hemin/G4-DNA complex was then formed and acted as a mimic of horseradish peroxidase, catalysing the proximal labelling of tyramine-modified gold nanoparticles to induce silver-enhanced electrochemical signal amplification. Electrochemical results demonstrated that the method was able to specially identify MUC1-positive tumor cells and generate corresponding electrochemical responses in the range of 100 cells per mL to 1 × 10⁶ cells per mL with a detection limit of 21 cells per mL. Furthermore, the method displayed good stability and anti-interference performance in complex serum environments. Therefore, our work may provide an effective tool to improve the accuracy of cell-based tissue examination and liquid biopsy for early diagnosis of cancers in the future.

Electrochemical sensors are increasingly garnering attention as valuable tools for point-of-care (POC) testing due to their low costs, high sensitivities, and ease of miniaturization. Graphene-based materials, renowned for their tunable electrical conductivity, high specific surface areas, versatile functionality, and biocompatibility; are highly suited for the fabrication of electrochemical sensors with heightened sensitivities. Non-contact, maskless, direct writing methods allow the rapid, large-scale production of graphene electrodes with high design flexibility. Researchers globally are advancing graphene electrode production, aiming for smaller, faster, and more efficient sensors. This review provides a comprehensive overview of recent advances on the direct writing of graphene electrodes for electrochemical sensing applications. It covers the basics of direct writing techniques, the advancements in graphene ink/precursor preparation, structural design, and device integration, with a focus on POC platforms.

The development of sensitive and accurate fluorescence sensors for the detection of anions and reactive oxygen species (ROS, H₂O₂) is essential as they play significant roles in biological and chemical processes. In this work, semiconductor La QDs were synthesized. The synthesized La QDs were determined to be pure with 100% La element using EDS technique. La QDs were observed in both cubic and hexagonal lattice configurations through powder XRD analysis. The morphology of the La QDs was characterized using HRTEM and FESEM data as tiny, spherical, homogenous QDs with a diameter ranging from 2 to 6 nm. The fluorescence characteristics of the synthesized La QDs were examined by studying their sensing properties that increased with an increase in anion concentration and decreased with an increase in [H₂O₂]. The variation in emission intensity at 315 nm and 440.5 nm satisfied the Stern–Volmer equation. The LOD and LOQ of H₂O₂ and anion sensing with La QDs were studied in the μM range. The Langmuir binding plots and FTIR spectra supported the concept that the surface functionalization of La QDs occurred in the presence of anions. With two band gap energies of about 3.26 eV and 4.66 eV, the synthesized La QDs are a mixture of two (binary) semiconductors.

The development of gadolinium-based contrast agents (GBCAs) has been pivotal in advancing magnetic resonance imaging (MRI), offering enhanced soft tissue contrast without ionizing radiation exposure. Despite their widespread clinical use, the need for improved GBCAs has led to innovations in ligand chemistry and polymer science. We report a novel approach using methacrylate-functionalized DO3A ligands to synthesize a series of copolymers through direct reversible addition-fragmentation chain transfer (RAFT) polymerization. This technique enables precise control over the gadolinium content within the polymers, circumventing the need for subsequent conjugation and purification steps, and facilitates the addition of other components such as targeting ligands. The resulting copolymers were analysed for their relaxivity properties, indicating that specific gadolinium-DO3A loading contents between 12–30 mole percent yield optimal MRI contrast enhancement. Inductively coupled plasma (ICP) measurements corroborated these findings, revealing a non-linear relationship between gadolinium content and relaxivity. Optimized copolymers were synthesized with the claudin-1 targeting peptide, C1C2, to image BBB targeting in aged mice to show imaging utility. This study presents a promising pathway for the development of more efficient GBCA addition to copolymers for targeted drug delivery and bioimaging application.

We report on the advantages of a green method to detect surfactants in environmental water samples. The approach is based on the use of a hydrophobic natural deep eutectic solvent (NADES) to extract the complexes formed by the surfactants and methylene blue. The concentration of the surfactant is then determined by measuring the color intensity in the organic phase using a smartphone. Under optimized conditions, an aliquot of 3 mL of the NADES was mixed with 15 mL of water, and then allowed to settle (to enable the separation of the two phases) for 5 min. The procedure allowed quantification of sodium dodecyl sulfate (SDS), as a proxy for alkyl surfactants in the range from 0.010 mg L⁻¹ to 0.600 mg L⁻¹, with a detection limit of 2.0 μg L⁻¹. Besides being a simple alternative to the traditional method (which requires chloroform and a spectrophotometer), the proposed approach offers low waste generation, low power-consumption, and fast analysis time, and is fully compatible with the plastic supplies (e.g. cuvettes, pipettes, tips, etc.) typically used for on-site analysis. The applicability of the approach was demonstrated by measuring various surface water samples and the overall green score of the method was calculated to be 96%.

Quantum dot-based biosensors have gained prominence in recent times for the detection of biological and chemical hazards present in aquatic media which essentially contribute to the degradation of the environment and human health. Within this work, we demonstrate a WS₂ QD-induced turn-on fluorescent probe for specific monitoring of ofloxacin (OFL) and ciprofloxacin (CIP) residues in water. An efficient one-pot hydrothermal approach is applied for fluorescent water-soluble WS₂ QD preparation. The WS₂ QDs possess excellent photostability and monodispersity along with a superior shelf life. The WS₂ QDs interacting with FQns (OFL and CIP) showed a systematically enhanced fluorescence in varying FQn concentrations from 0 μM to 3 μM. Also, all the measurements showed excellent results for sensitivity along with superior specificity as well as anti-interference ability over other interfering substances like various metal ions and antibiotic derivatives. The proposed sensor allows the quantification of FQns in the range of 0–3 μM with the lowest detectable amount (LOD) of 0.08 μM and 0.06 μM and the minimal limit of quantification (LOQ) of 0.26 μM and 0.21 μM for both OFL and CIP, respectively, at natural pH. It achieved higher sensitivity than many established techniques and materials making up the gap of other existing systems in this range. We observed excellent results for the rapid in situ detection of FQns by implementing WS₂ QDs. The findings show potential for future use in real-time applications for FQns.

We report the rapid fabrication of a handheld laser cut platform that can support the assembly, functionalisation, size-control and electrical characterisation of lipid bilayers. We achieve this by building a modular DIY platform that can support the lowering of a Ag/AgCl electrode through a phase transfer column consisting of an upper oil phase containing lipids, and a lower aqueous phase containing buffer.