Ultrasensitive Electrochemiluminescence Biosensor Based on 2D Co3O4 Nanosheets as a Coreaction Accelerator and Highly Ordered Rolling DNA Nanomachine as a Signal Amplifier for the Detection of MicroRNA.

A novel ultrasensitive electrochemiluminescence (ECL) biosensor was constructed using two-dimensional (2D) Co3O4 nanosheets as a novel coreaction accelerator of the luminol/H2O2 ECL system for the detection of microRNA-21 (miRNA-21). Impressively, coreaction accelerator 2D Co3O4 nanosheets with effective mutual conversion of the Co2+/Co3+ redox pair and abundant active sites could promote the decomposition of coreactant H2O2 to generate more superoxide anion radicals (O2•-), which reacted with luminol for significantly enhancing ECL signals. Furthermore, the trace target miRNA-21 was transformed into a large number of G-wires through the strand displacement amplification (SDA) process to self-assemble the highly ordered rolling DNA nanomachine (HORDNM), which could tremendously improve the detection sensitivity of biosensors. Hence, on the basis of the novel luminol/H2O2/2D Co3O4 nanosheet ternary ECL system, the biosensor implemented ultrasensitive detection of miRNA-21 with a detection limit as low as 4.1 aM, which provided a novel strategy to design an effective ECL emitter for ultrasensitive detection of biomarkers for early disease diagnosis.

Aluminum(III)-Based Organic Nanofibrous Gels as an Aggregation-Induced Electrochemiluminescence Emitter Combined with a Rigid Triplex DNA Walker as a Signal Magnifier for Ultrasensitive DNA Assay.

Due to effective tackling of the problems of aggregation-caused quenching of traditional ECL emitters, aggregation-induced electrochemiluminescence (AIECL) has emerged as a research hotspot in aqueous detection and sensing. However, the existing AIECL emitters still encounter the bottlenecks of low ECL efficiency, poor biocompatibility, and high cost. Herein, aluminum(III)-based organic nanofibrous gels (AOGs) are used as a novel AIECL emitter to construct a rapid and ultrasensitive sensing platform for the detection of Flu A virus biomarker DNA (fDNA) with the assistance of a high-speed and hyper-efficient signal magnifier, a rigid triplex DNA walker (T-DNA walker). The proposed AOGs with three-dimensional (3D) nanofiber morphology are assembled in one step within about 15 s by the ligand 2,2':6',2″-terpyridine-4'-carboxylic acid (TPY-COOH) and cheap metal ion Al3+, which demonstrates an efficient ECL response and outstanding biocompatibility. Impressively, on the basis of loop-mediated isothermal amplification-generated hydrogen ions (LAMP-H+), the target-induced pH-responsive rigid T-DNA walker overcomes the limitations of conventional single or duplex DNA walkers in walking trajectory and efficiency due to the entanglement and lodging of leg DNA, exhibiting high stability, controllability, and walking efficiency. Therefore, AOGs with excellent AIECL performance were combined with a CG-C+ T-DNA nanomachine with high walking efficiency and stability, and the proposed "on-off" ECL biosensor displayed a low detection limit down to 23 ag·µL-1 for target fDNA. Also, the strategy provided a useful platform for rapid and sensitive monitoring of biomolecules, considerably broadening its potential applications in luminescent molecular devices, clinical diagnosis, and sensing analysis.

A systematic review and meta-analysis of the correlation between maternal and neonatal iron status and haematologic indices.

BACKGROUND: Iron deficiency (ID) is the leading single-nutrient deficiency in the world. Anaemia is a common outcome of ID that affects half of pregnancies worldwide with serious consequences for child development. Whether haematologic indices and biomarkers of iron status in pregnant women correlate with those of their neonates is unclear. This systematic review evaluated studies comparing haematologic and iron status indices in pregnant women and their newborns/neonates. METHODS: We searched MEDLINE, EMBASE, CINAHL, and Web of Science from database inception until March 2020 for primary studies comparing haematologic and iron status indices between women and their newborns up to 48 h after birth. We summarized the results descriptively and calculated pooled correlation coefficients in mothers and newborns/neonates using the Schmidt-Hunter method. The protocol was registered at PROSPERO International Prospective Register of Systematic Reviews (Registration number: CRD42018093094). FINDINGS: Sixty-five studies were included. Pooled correlation coefficients for biomarkers of iron status in mothers and newborns/neonates were 0.13 (ferritin), 0.42 (hepcidin), 0.30 (serum/plasma iron), 0.09 (transferrin), 0.20 (transferrin saturation), and 0.16 (total iron binding capacity). Pooled correlation coefficients for haematological indices in mothers and newborns/neonates were 0.15 (haemoglobin), 0.15 (haematocrit), 0.25 (mean cell/corpuscular haemoglobin), 0.22 (mean cell/corpuscular volume). INTERPRETATION: Maternal biomarkers of iron and haematologic status correlate poorly with those in newborns/neonates. These results underscore a need for alternative approaches to estimate foetal/neonatal iron status and haematological indices. FUNDING: MBO and SLB hold Canada Research Chairs, and grants from the Women and Children's Health Research Institute and Canadian Institutes of Health Research.

Numerical analysis on the shear behavior of single-keyed dry joints in precast high-strength concrete segmental bridges.

The structural behavior of precast concrete segmental bridges (PCSBs) is affected by the joints between the concrete segments. In this study, a numerical model was established to investigate the direct shear behavior of single-keyed dry joints in PCSBs. The numerical model was validated by the full-scale test results published by the authors. It was found that the numerical results of the joints, such as the ultimate shear load, cracking pattern, and load-displacement curves, matched the test results well. The validated numerical model was further used for extending parametric studies. The factors affecting the shear behavior of single-keyed dry joints include the confining pressure, concrete strength, and key depth. It was found that the ultimate shear capacity increased about 121% when the confining pressure increased from 0.1 to 3.0 MPa, it was very low under confining pressure of 0.1 MPa; it increased about 44% when the concrete strength increased from C40 to C100; it increased about 203% when the key depth increased from 15 to 40 mm. However, the ultimate shear capacity decreased about 20% when the key depth increased from 40 to 60 mm, hence 40 mm was recommended for the design depth of the single-keyed dry joints in PCSBs. Finally, the parametric analysis results were compared with the AASHTO specification. When the key depth was 35, 40 and 45 mm, the AASHTO specification conservatively predict the shear strength capacity of single-keyed dry joints.

Nondestructive and intuitive determination of circadian chlorophyll rhythms in soybean leaves using multispectral imaging.

The circadian clock, synchronized by daily cyclic environmental cues, regulates diverse aspects of plant growth and development and increases plant fitness. Even though much is known regarding the molecular mechanism of circadian clock, it remains challenging to quantify the temporal variation of major photosynthesis products as well as their metabolic output in higher plants in a real-time, nondestructive and intuitive manner. In order to reveal the spatial-temporal scenarios of photosynthesis and yield formation regulated by circadian clock, multispectral imaging technique has been employed for nondestructive determination of circadian chlorophyll rhythms in soybean leaves. By utilizing partial least square regression analysis, the determination coefficients R(2), 0.9483 for chlorophyll a and 0.8906 for chlorophyll b, were reached, respectively. The predicted chlorophyll contents extracted from multispectral data showed an approximately 24-h rhythm which could be entrained by external light conditions, consistent with the chlorophyll contents measured by chemical analyses. Visualization of chlorophyll map in each pixel offers an effective way to analyse spatial-temporal distribution of chlorophyll. Our results revealed the potentiality of multispectral imaging as a feasible nondestructive universal assay for examining clock function and robustness, as well as monitoring chlorophyll a and b and other biochemical components in plants.