Sensors & diagnostics最新文献

Electrochemical aptamer-based (E-AB) sensors achieve detection and quantitation of biomedically relevant targets such as small molecule drugs and protein biomarkers in biological samples. E-ABs are usually fabricated on commercially available macroelectrodes which, although functional for rapid sensor prototyping, can be costly and are not compatible with the microliter sample volumes typically available in biorepositories for clinical validation studies. Seeking to develop a multi-point sensing platform for sensor validation in sample volumes characteristic of clinical studies, we report a protocol for in-house assembly of 3D-printed E-ABs. We employed a commercially available 3D stereolithographic printer (FormLabs, $5k USD) for electrochemical cell fabrication and directly embedded electrodes within the 3D-printed cell structure. This approach offers a reproducible and reusable electrode fabrication process resulting in four independent and simultaneous measurements for statistically weighted results. We demonstrate compatibility with aptamer sequences binding antibiotics and antineoplastic agents. We also demonstrate a proof-of-concept validation of serum vancomycin measurements using clinical samples. Our results demonstrate that 3D-printing can be used in conjunction with E-ABs for accessible, rapid, and statistically meaningful validation of E-AB sensors in biological matrices.

Monitoring of creatinine in human fluid has attracted considerable attention owing to the potential for diagnosis of chronic kidney disease. However, the detection of creatinine has been difficult owing to its electrochemical and optical inertness. In this approach, a highly selective and sensitive electrochemiluminescence (ECL) strategy based on homogeneous carbon quantum dots (CQDs) for the detection of creatinine was introduced. A copper(II) picrate complex was added at the surface of electrode to improve the selectivity of the sensor significantly by the formation of a Janovsky complex. A multi-pulse amperometric technique was applied as a very fast and reliable method for quantitative determination of creatinine. The calibration curve was acquired with a linear range from 1.0 × 10⁻⁸ to 1 × 10⁻⁵ M with a low detection limit of 8.7 × 10⁻⁹ M. The proposed creatinine sensing platform is experimentally very simple and shows high selectivity with a broad linear range of detection. Furthermore, the presented method can determine creatinine in real samples with excellent recoveries.

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.