Power Noonan (ricegauge99)
The limit of detection (LOD) was 229 particles μL-1 with a linear range from 5 × 102 particles μL-1 to 5 × 105 particles μL-1. An electrochemical biosensor can detect exosomes secreted by various cancer cells such as HeLa, OVCAR and BT474, and shows a high specificity even in serum samples, thus demonstrating its great potential in the application of clinical diagnostics. This proposed electrochemical biosensor provides a facile and efficient tool for the early diagnosis of cancers.MicroRNAs (miRNAs) are related to many biological processes and regarded as biomarkers of disease. Rapid, sensitive, and specific methods for miRNA assay are very important for early disease diagnostic and therapy. In the present work, an ultrasensitive electrochemical biosensing platform has been developed for miRNA-21 assay by combining CRISPR-Cas13a system and catalytic hairpin assembly (CHA). In the presence of miRNA-21, it would hybridize with the spacer region of Cas13a/crRNA duplex to activate the cleavage activity of CRISPR-Cas13a system, leading to the release of initiator of CHA to generate amplified electrochemical signals. Base on the CRISPR-Cas13a-mediated cascade signal amplification strategy, the developed electrochemical biosensing platform exhibited high sensitivity with a low detection limit of 2.6 fM (S/N = 3), indicating that the platform has great potential for application in early clinical diagnostic.Cerium is the most abundant rare earth element (REE) in the solar photosphere, CI chondrites, and the Earth. It has four main stable isotopes (masses 136,138,140, and 142), with 138Ce being the most studied species, used in geochronology and petrogenesis. In addition, more abundant 140Ce and 142Ce are suggested to be potentially applicable in geochemical investigations. In this work, we developed a modified four-step ion chromatography procedure for Ce chemical separation. Using a MC-ICPMS, we designed a cup configuration to measure 142Ce/140Ce ratio of the samples with an optimized Nd correction equation. A 0.03‰ (2SD) reproducibility was obtained for Ce Ames metal standard. We analyzed ten different igneous and one sedimentary geochemical reference materials. Mean δ142Ce range from -0.07 to 0.32‰. Most of the samples show a heavier Ce isotopic composition than the Ce Ames standard. The majority of rocks have a homogenous δ142Ce. The δ142Ce does not show any correlation with rock chemical composition including their Ce content or rock types. A carbonatite (SARM 40) has a mean δ142Ce of -0.07 ± 0.13‰ (2SD), lower than the other rocks, suggesting the possibility of a pronounced isotopic fractionation. Our work demonstrates the applicability of the developed methodology and the potential of Ce stable isotopes for future geochemical studies. Production of a larger database of δ142Ce values is required to obtain a clearer view on the similarities and differences between different geological material and explaining Ce stable isotope dynamics.Development of efficient adsorbents for the enrichment of trace contaminants from complex matrix still remains great challenge and interest. Here we report the decoration of amino microporous organic network on zeolitic imidazolate framework (ZIF)-67 derived nitrogen-doped carbon (Co@NC-MON-2NH2) for efficient magnetic solid phase extraction (MSPE) of plant growth regulators (PGRs) from vegetables. The ZIF-67 was calcined to produce Co and N co-doped porous carbon (Co@NC), serving as the magnetic separation module and the core for in-situ growth of MON-2NH2 shell. The Co@NC-MON-2NH2 owned large surface area, good magnetic property and stability, giving high affinity to PGRs via multiple extraction mechanisms such as hydrogen bonding, π-π and hydrophobic interactions. Under optimal conditions, the Co@NC-MON-2NH2 based MSPE-HPLC-UV method gave wide linear range, good precisions, large enrichment factors, less adsorbent consumption and low limit of detections for the studied PGRs. The proposed MSPE-H
