Sensors & diagnostics最新文献

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.

Saxitoxin (STX) as one of the paralytic shellfish toxins has become a serious public health and environmental issue. In this regards, developing highly sensitive and selective biosensors may help find a solution. Herein, a ferrocene (Fc)-labeled DNA walker coupled with nicking endonuclease Nb.BbvCI was used to construct a sensitive electrochemical aptasensor for STX detection. First, an amplified DNA, aptamer and DNA walker formed a sandwich structure on a gold electrode. This structure was disintegrated when STX was added, resulting in the hybridization of the amplified DNA and DNA walker. Thereafter, the DNA walker was activated by Nb.BbvCI to achieve stepwise cleavage of the hybridized amplified DNA. The released Fc-amplified DNA generated an electrochemical signal that decreased linearly with the logarithm value of STX concentration in the range of 1 pM–100 nM with a detection limit of 0.58 pM. Meanwhile, the proposed aptasensor exhibited good selectivity and recovery rate. The DNA walker coupled with the nicking endonuclease provides effective signal amplification for the detection of toxins and fabrication of sensitive aptasensors.

Wearable physical sensors represent attractive devices for health monitoring and human–machine interfaces. Unlike traditional devices that prioritize increased sensitivity and selectivity, stretchability is crucial for wearable sensors to effectively adhere to the dynamic and curved contours of the human body. In addition to being stretchable, the conformal integration allows for durable skin–device interfaces, enabling long-term wearable detection. To track the latest progress, this perspective focuses on the rapidly advancing field of skin-attached physical sensors, analyzing their design approaches, critical applications, and desirable characteristics. The discussion begins with two primary strategies for creating stretchable electronic devices through structural designs and material innovations. We further discuss the significance of a conformal, seamless skin–device interface for wearable detection. We further elaborate on several critical physical sensors and their system integration. Finally, this article addresses current challenges and outlines future directions to translate knowledge in this evolving field into cutting-edge wearable technologies.

Tumor cells have high metabolic demands, leading to increased oxygen consumption and further exacerbating hypoxia, which has been regarded as a characteristic feature of solid tumors and plays a significant role in tumor growth, resistance to therapy, and overall treatment outcomes. Hypoxia-specific sensing probes are currently in urgent need to provide valuable information for tumor detection and monitoring. In this work, we developed a new near-IR fluorescence-emitting biosensor with a high fluorescence quantum yield for hypoxia detection in tumor tissues. In the presence of nitroreductase enzyme under tumor hypoxia, the nitro group of the biosensor molecule is converted into an amino group, and the resulting compound turns itself into a nonfluorescent dye through a self-immolating process, thus turning off the fluorescence emission of the biosensor. The fluorescence change of the biosensor in response to nitroreductase is sensitive and selective and is not influenced by the presence of other physiologically important species. In the in vitro and in vivo bioimaging experiments, the biosensor demonstrated high efficiency in detecting hypoxia and the capability of distinguishing solid tumors of different sizes, indicating its potential applications in tumor diagnosis and progression monitoring.

We report the facile detection of a pancreatic cancer biomarker α-chymotrypsin (Chy) by turn-on, time-gated lanthanide luminescence for the first time. To the best of our knowledge, the non-peptide probe we designed is the simplest one currently available. The probe undergoes Chy-induced release of the sensitizing antenna (2,3-dihydroxynaphthalene), leading to enhanced lanthanide luminescence. The detection protocol was further modified to develop a paper-based sensor and was used to detect Chy in commercial tablets, and to rapidly screen Chy-inhibitors.