Sensors & diagnostics最新文献

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.

Genetically-encoded, fluorescent protein (FP)-based biosensors are powerful tools for imaging dynamic cellular activities. Directed evolution is a highly effective method for developing enhanced versions of FP-based biosensors, but the screening process is laborious and time-consuming. Mammalian cell-based screening with electrical stimulation methods has been successful in accurately selecting variants of biosensors for imaging neuronal activities. We introduce an automated mammalian cell screening platform utilizing a fluorescence microscope and a liquid dispenser to enable the screening of biosensor responsiveness to chemical stimulation. We demonstrated the effectiveness of this platform in improving the response of a red fluorescent biosensor for Ca²⁺, K-GECO, for detection of histamine-induced changes in Ca²⁺ concentration. This method should be applicable to any FP-based biosensor that responds to pharmacological treatment or other exogenous chemical stimulation, simplifying efforts to develop biosensors tailored for specific applications in diverse biological contexts.

Accurately identifying tumor tissue is crucial during surgery, especially when removing head and neck squamous cell carcinomas (HNSCC). Our tumor-responsive probes are tailored for ex vivo diagnostics, streamlining today's complex surgical workflows and potentially enabling pathologists and surgeons to rapidly and objectively distinguish between healthy and tumor tissue. Designed based on insights from biological furin substrates and cleavage site screening, the probes detect HNSCC-associated protease activity. Within ten minutes of incubation, tumor tissue is differentiated from healthy tissue by visible fluorescence in biopsy supernatant.

Glycated hemoglobin (HbA1c) is a pivotal biomarker for the monitoring and early diagnosis of diabetes. The CRISPR-Cas system has fascinating application prospects in the next generation of biosensors due to its high specificity, efficiency, flexibility, and customization. Herein, a label-free electrochemical aptasensor was designed for the detection of HbA1c by combining the specific recognition ability of aptamers with the signal amplification effect of the CRISPR-Cas12a system. In the presence of HbA1c, the cis–trans cleavage ability of Cas12a protein was activated, causing the pre-formed probe DNA to be heavily cleaved and the electrochemical signal to increase. With CRISPR-assisted signal amplification, the developed electrochemical aptasensor can detect as low as 0.84 ng mL⁻¹ HbA1c. Moreover, this aptasensor can detect 10 ng mL⁻¹ HbA1c in 50% human serum due to its high selectivity, reproducibility, and long-term stability, which is lower than its physiological level in human blood samples. All results proved that the proposed aptasensor has a promising application in the early diagnosis and long-term monitoring of diabetes.