查看更多>>摘要：To improve gas sensing performance of oxide semiconductor is a collective goal of science community, due to that gas sensor is a class of pivotal component of environmental monitoring, the Internet of things and medical equipment. We introduced isolated single platinum atoms on the defective WO_(3-x) nanosheets (SA-Pt/WO_(3-x)), and investigated the status of single atoms by XPS, HAADF-STEM and in situ FT-IR and so forth. The SA-Pt/ WO_(3-x) based sensor exhibits high response level (R_a/R_g=43.4 to 5 ppm), exceptional ultrahigh selectivity (S_(best)/ S_(second)=2.8) and ultimate detection limit (R_a/R_g=4.3 to 0.1 ppm) in acetone gas sensing. In addition, the counterparts of WO_3 and Pt nanoparticles were utilized as comparison to investigate the synthesis and gas sensing mechanism thoroughly. This work illustrates the research to fit the needs of ultralow concentration gas sensor application.
查看更多>>摘要：Diquat (DQ) is widely applied in the agriculture industry to ensure crop yield and quality, but this compound poses a serious hazard to human beings. The design of an efficient sensing platform for DQ is essential for food safety and environmental protection. Here, we developed a radiative charge recombination chemiluminescence (CL) using silicon nitride nanoparticles (Si_3N_4 NPs) as luminophore via hypochlorite (NaClO) activation for DQ quantification. With more active sites (N-Cl) on the surface of Si_3N_4 NPs, Si_3N_4 NPs displayed specific CL performance toward DQ. Accordingly, a new CL system for DQ detection was fabricated with satisfactory linearity (10-200 μg/L) and detection limit (6.1 μg/L), relative standard deviation (RSD) was lower than 1%. This new CL assay does not respond to other pesticides, and no interferences from metal ions that have been reported before in the DQ CL sensors. The CL mechanism was proposed that Si_3N_4 NPs act as the catalyst to accelerate the generation of superoxide radical (O_2~(·-)) from DQ, and then the radiative charge recombination of Si_3N_4 NPs occurs between the O_2~(·-) and exogenous holes for extraordinary CL emission. This work provides a general route for the construction of nanoparticle CL probe, which will aid in the monitoring of pollutants.
查看更多>>摘要：The development of a low-cost, high-sensitivity, portable bioassay for detecting the highly toxic and thermally stable aflatoxin B_1(AFB_1) is of significant importance to food safety and human health. A pipette-smartphone integrated biosensor based on a super "four-in-one" DNA sea-urchin-like composite catalyst (FSCC) was constructed for the efficient analysis of AFB_1. Detection is possible via a self-made poly(methyl methacrylate) pipette, combined with a smartphone to further increase the biosensor's portability. The combination of the two greatly simplifies experimental operations, reduces testing costs, and can minimize matrix interferences through sample pre-treatment operations. And the smartphone-APP signal readout strategy can avoid the need for a reading instrument, making it more suitable for field testing. The FSCC was developed by fully utilizing the properties of a Fe-Zr-metal-organic framework (Fe-Zr-MOF), which exhibits high catalytic activity and enables the encapsulation of abundant horseradish peroxidase in its pores, the in-situ reduction and enrichment of Pt nanoparticles on its surface, and the coordination of biotinylated DNA to achieve a high adsorption capacity of streptavidin-horseradish peroxidase. This ensured detection sensitivity, with a limit of detection = 1.57 pg/mL. The developed biosensor displays notable application potential, especially in resource-poor areas due to the advantages of low costs, simple operation, ultra-high sensitivity, portability, etc.
查看更多>>摘要：Intracellular hydrogen sulfide (H_2S) and micro-environments (e.g. viscosity and polarity) are tightly correlated with various physiological/pathological processes, making them potential biomarkers of many diseases. However, the simultaneously detecting H_2S, viscosity, and polarity in inflammation, non-alcoholic fatty liver (NAFL) and tumor tissues containing clinical cancer patient samples has not been achieved yet due to the lack of effective tools. Herein, we presented a mitochondria-targeting near-infrared (NIR) fluorescent probe MQA-DNP) for simultaneously monitoring H2S, viscosity/polarity through dual channels. The probe could specifically recognize H_2S via far-red emission (λ_(em) = 634 nm), and exhibited high sensitivity toward micro-environmental viscosity/ polarity in the NIR channel (λ_(em) ＞ 714 nm). Facilitated with the probe, we revealed for the first time that inflammation cells and NAFL tissues are accompanied by an up-regulation of H_2S, as well as an increase in viscosity level (and/or decrease in polarity degree). Surprisingly, the simultaneous visualization of H_2S, viscosity/polarity has also been achieved not only at the cancer cells and tumor models, but also in clinical cancer patients. Compared to detecting a single biomarker, the simultaneous tracking multi-markers through multichannels seems to be more reliable for visual medical diagnosis of mitochondria-related diseases. Furthermore, inspired by the significant color changes and high sensitivity of MQA-DNP reaction with H2S, MQA-DNP has been successfully used to detect H_2S released during food spoilage through test strips, and has great potential for application in complex environments systems.
Ashutosh KumarKuldeep MahatoDaphika S. DkharAnanya Srivastava...
134605.1-134605.10页
查看更多>>摘要：External redox reagents and chemical mediators in measuring solutions are extensively used to monitor the analytical signals in electrochemical immunosensors. These mediators add more steps and complications to the sensing procedures which are aggravated when testing the target molecule in real samples. Thus, it is important to resolve such issues by fabricating and engineering sensitive electroactive surfaces without the requirement of mediators in the solution phase. In this work, we report a self-reporting electrochemical biosensor for cyfra-21-1 detection in saliva samples without using any external mediator molecules in solution phase. To fabricate an electrochemically active surface, a redox active Gadolinium hexacyanoferrate (GdHCF) nanoparticles have been synthesized and deposited onto the electrode surface for label-free detection of cyfra-21-1 in combination with gold nanoparticles (AuNP) and graphene oxide (GO). The sensor probe was thoroughly characterized using X-ray diffraction (XRD), UV-vis spectroscopy, transmission electron microscopy (TEM), Raman Spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry CCV), and electrochemical impedance spectroscopy (EIS). An alternation in the protein biomarker concentrations led to a change in the current response of the electrode surface, differential pulse voltammetry (DPV) was used to establish the analytical performance of the fabricated biosensor. The sensor achieved a clinically relevant range as well as a wide linear dynamic range (LDR) of 2-50 ng/mL of cyfra-21-1 and a detection limit (DL) of 0.039 ( ± 0.01) ng/mL ((RSD ＜ 4.12%, 95% confidence level, n = 3), with negligible interferences effect due to various co-existing molecules. This is the first-ever report where a redox-active surface has been fabricated comprising GdHCF for direct detection of cyfra-21-1 in human saliva samples without using any redox mediator in the solution phase.
查看更多>>摘要：The existence of many background cells and the size overlap between white blood cells (WBCs) and malignant tumor cells (MTCs) pose a challenge for the efficient separation of MTCs from effusions or bloods. Herein, we proposed an inertia-magnetic cell separation (IMCS) device integrating a trapezoidal spiral chip with an immunomagnetic chip for high-throughput, high-recovery, and high-purity separation of MTCs from malignant pleural and peritoneal effusions (MPPEs). First, the effects of flow rate and particle size on separation performances in two separate chips were investigated. Then, the performances of the integrated IMCS device were characterized using blood samples spiked with three different tumor cells (A549, MCF-7, and MDA-MB-231 cells). The results showed that all the three tumor cells were separated from the WBCs with a high-throughput of ～3200 μL/min, a high-recovery ratio of ＞ 90%, and a high-purity of ＞ 70%. Finally, we successfully separated MTCs from four clinical MPPE samples with an average purity of ＞ 70%. As compared with conventional microfluidic devices using single technologies, our IMCS device combines the advantages of both passive size-dependent separation technology and immunomagnetic separation technology and can accurately separate tumor cells from WBCs of comparable sizes at a high throughput. Therefore, we envision that the high-purity MTC separation ability of our IMCS device can improve the sensitivity and efficiency of cytological examination.
Amanda Akemy KomorizonoBruno Sanches de LimaValmor Roberto Mastelaro
134621.1-134621.9页
查看更多>>摘要：Gas sensors based on graphene nanocomposites have been widely investigated for the detection of different gases. However, few studies have reported graphene-based materials for ozone (O_3) detection due to a permanent oxidation reaction between ozone and carbon atoms from graphene structure that leads to degradation of the material and poor sensing stability. Such an effect, called ozonolysis, is enhanced at higher temperatures. This article addresses the development of new techniques for the use of rGO-ZnO nanocomposites for ozone detection. A commercial rGO suspension was mixed with ZnO nanoparticles prepared by Pechini method. The study proposes two different production methods, according to which 1) ZnO nanoparticles are deposited over the surface of an rGO layer (labeled as rGO/ZnO) and 2) ZnO nanoparticles "sandwich" the rGO layer (labeled as ZnO/rGO/ ZnO). ZnO/rGO/ZnO samples showed no degradation when exposed to ozone and exhibited higher and more stable and efficient responses than rGO/ZnO. The results agree with surface and morphology characterizations through XPS and SEM, suggesting the rGO layer should be covered by ZnO nanoparticles to be stable and efficient for ozone detection.
查看更多>>摘要：Unaware fatigue causes inefficiencies and unsafe behaviors. Therefore, an easily-used technique to monitor labor intensity is critical. In this work, the humidity-sensitive material Cs_3Cu_2I_5 was used to monitor breath and grade labor intensity without contact. The Cs_3Cu_2I_5 showed reversible conversion to the CsCu_2I_3 phase by being exposed to water. EMI-TFSI was added to improve the material's conductivity and electrochemical stability, helping to passivate surface defects and adjust the response sensitivity. Further mechanism explanation was explored by density functional theory calculation and electrochemical impedance spectroscopy. Switching from 40 % RH to 90 % RH, the sensor resistance changed by 161.3 megohms with a relative change ratio of 0.967. Besides, the sensor has a short response/recovery time (e.g., 2.0/0.5 s switching from 40 % RH to 60 % RH), with good repeatability and stability in high humidity. Then, the developed high-performance lead-free sensor was integrated into a smart mask with a neural network algorithm to monitor and forecast breath, and grade labor intensity. The model was built with 240 sample data and 19 constructed features. The accuracy of identifying three intensity levels in external validation was 0.9. Based on the sensing data and the grading model, a real-time labor intensity monitoring and visualization platform was constructed.
Kevin ThomschkeNadja SteinkeMarisa RioThomas Hartling...
134624.1-134624.7页
查看更多>>摘要：Localized surface plasmon resonance (LSPR) sensors allow the label-free detection of molecules in real-time with a high sensitivity, which makes them suitable for the detection of various molecules. However, the experimental characterization of the surface functionalization and the molecular binding on the nanostructured sensor surface represent black boxes. To overcome these uncertainties, this study shows an approach to simulate and experimentally validate the plasmonic response upon molecular binding to a LSPR sensor for the detection of diclofenac (DCF). Assuming homogeneous molecular coverage and averaged parameters such as refractive index and layer thickness through the combination of an iterative experimental validation and electrodynamics simulations a coherent model was formed that includes the uncertainties of molecular binding. This validated model and the obtained parameter for the biochemical assay forms the basis for a future automated optimization of the nanostructure geometry with respect to increased sensitivity to molecular binding.
查看更多>>摘要：This paper discusses the utilization of water stable, biocompatible CsPbBr_3 perovskite quantum dots (BPQDs) as donors in combination with Rhodamine 6G (R6G) as acceptors, as ratiometric probe, for detection of pathogens and water contaminants via the fluorescence resonance energy transfer (FRET) mechanism. Biocompatibility of BPQDs was attained through phase engineering using succinic acid (SA) ligand which at appropriate pH provides carboxylic environment on the outer surface, facilitating transfer to aqueous phase. Photoluminescence (PL) studies on ratiometric probe reveal quenching of BPQDs' emission with a simultaneous enhancement of R6G fluorescence, representing a singlet energy transfer. The probe was successfully validated for ratiometric sensing of a model carcinogen (thioacetamide (TAA)) and a model pathogen (Escherichia coli (E. coli)) and the detection limit achieved was 1.8 CFU/mL for E. coli sensing and 1.5 μM for TAA sensing. Dual emission and its quenching mechanism involved in the detection of aforesaid analytes have been elaborately discussed and elucidated, indicating that quenching mechanisms are different for the two analytes. Our work not only demonstrates an important milestone for the integration of perovskite quantum dot in clinical diagnostics but also as an easy, unique, rapid and accurate E. coli detection technique that is complimentary to the rather complicated high throughput and high-sensitivity approaches that are existing.
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Elsevier