[Analysis of Spatio-temporal Distribution Characteristics and Influencing Factors of PM2.5 Concentration in Urban Agglomerations on the Northern Slope of Tianshan Mountains].

Analysis of the spatial and temporal distribution characteristics and influencing factors of PM2.5 concentrations for the urban agglomeration on the northern slope of Tianshan Mountain is of positive significance for regional economic construction and environmental protection. The spatial and temporal distributions of PM2.5 concentrations in the Tianshan North Slope urban agglomeration from March to November 2015 to 2021 were obtained through the inversion of the MCD19A2 aerosol product combined with meteorological factors using a geographically weighted regression (GWR) model, followed by the analysis of change trends and influencing factors. The results were as follows:① the high PM2.5 concentrations in the study area were mainly distributed in the oasis city cluster between the northern foot of Tianshan Mountain and the Gurbantunggut Desert, showing the spatial distribution characteristics of being "low around and high in the middle" and "low in the west and high in the east." The annual average value of ρ(PM2.5) in the study area was 16.98 µg·m-3, with high values mainly concentrated in the urban part of Urumqi and decreasing towards Changji and Fukang. The monthly average ρ(PM2.5) distribution pattern was consistent with the annual average, but there were seasonal differences as follows:autumn (20.32 µg·m-3) > spring (18.25 µg·m-3) > summer (12.47 µg·m-3). The accumulation phenomenon was more pronounced in spring and winter. ② The study area's annual average PM2.5 concentration showed a decreasing trend from 2015 to 2021, and the average value from March to October also showed a decreasing trend, with only a slight increase in November. From the analysis of the spatial distribution of PM2.5 concentration trends, the decrease was concentrated in the urban parts of major cities, especially in the urban part of Urumqi and its surrounding areas, where the decrease was the largest and the change was the most drastic. ③ Temperature and air pressure were positively correlated with PM2.5 concentrations, whereas relative humidity, wind speed, atmospheric boundary layer height, and precipitation were negatively correlated with PM2.5 concentrations. The degree of influence of each factor was ranked from high to low as follows:atmospheric boundary layer height > relative humidity > air pressure > air temperature > wind speed > precipitation.

RNA imaging in living mice enabled by an in vivo hybridization chain reaction circuit with a tripartite DNA probe.

RNA imaging in living animals helps decipher biology and creates new theranostics for disease treatment. Due to their low delivery efficiency and high background, however, fluorescence probes for in situ RNA imaging in living mice have not been reported. We develop a new cell-targeting fluorescent probe that enables RNA imaging in living mice via an in vivo hybridization chain reaction (HCR). The minimalistic Y-shaped design of the tripartite DNA probe improves its performance in live animal studies and serves as a modular scaffold for three DNA motifs for cell-targeting and the HCR circuit. The tripartite DNA probe allows facile synthesis with a high yield and demonstrates ultrasensitive RNA detection in vitro. The probe also exhibits selective and efficient internalization into folate (FA) receptor-overexpressed cells via a caveolar-mediated endocytosis mechanism and produces fluorescence signals dynamically correlated with intracellular target expressions. Furthermore, the probe exhibits specific delivery into tumor cells and allows high-contrast imaging of miR-21 in living mice. The tripartite DNA design may open the door for intracellular RNA imaging in living animals using DNA-minimal structures and its design strategy can help future development of DNA-based multi-functional molecular probes.

Diastereoselective Synthesis of Oxazoloisoindolinones via Cascade Pd-Catalyzed ortho-Acylation of N-Benzoyl α-Amino Acid Derivatives and Subsequent Double Intramolecular Cyclizations.

The first cascade diastereoselective synthesis of oxazoloisoindolinones via the palladium-catalyzed decarboxylative ortho-acylation of N-benzoyl α-amino acid derivatives followed by double intramolecular cyclizations has been demonstrated. This reaction, using α-amino acids as directing groups and α-oxocarboxylic acids as the acylation source, features a broad substrate scope, good functional group tolerance, high regioselectivity, and excellent diastereoselectivity.

Cell Surface-Anchored DNA Nanomachine for Dynamically Tunable Sensing and Imaging of Extracellular pH.

DNA nanodevices that mimic natural biomolecular machines changing configurations in response to external inputs have enabled smart sensors to live cell imaging. We report for the first time the development of a dynamic DNA nanomachine that is anchored on a cell's surface and undergoes pH-responsive triplex-duplex conformation switching, allowing tunable sensing and imaging of extracellular pH. Results reveal that the DNA nanomachine can be stably anchored on the cell surface via multiple anchors, and the adjustment of C+G-C content in the switch element confers tunability of pH response windows. The anchored DNA nanomachine also demonstrates desirable sensitivity, excellent reversibility, and quantitative ability for extracellular pH detection and imaging. This cell surface-anchored pH-responsive DNA nanomachine can provide a useful platform for pH sensing in extracellular microenvironments and diagnostics of different pH-related diseases.

Branched Hybridization Chain Reaction Circuit for Ultrasensitive Localizable Imaging of mRNA in Living Cells.

Hybridization chain reaction (HCR) circuits are valuable approaches to monitor low-abundance mRNA, and current HCR is still subjected to issues such as limited amplification efficiency, compromised localization resolution, or complicated designs. We report a novel branched HCR (bHCR) circuit for efficient signal-amplified imaging of mRNA in living cells. The bHCR can be realized using a simplified design by hierarchically coupling two HCR circuits with two split initiator fragments of the secondary HCR circuit incorporated in the probes for the primary HCR circuit. The bHCR circuit enables one to generate a hyperbranched assembly seeded from a single target initiator, affording the potential for localizing single target molecules in live cells. In vitro assays show that bHCR offers very high amplification efficiency and specificity in single mismatch discrimination with a detection limit of 500 fM. Live cell studies reveal that bHCR displays intense fluorescence spots indicating mRNA localization in living cells with improved contrast. The bHCR method can provide a useful platform for low-abundance biomarker detection and imaging for cell biology and diagnostics.

Surface Enhanced Laser Desorption Ionization of Phospholipids on Gold Nanoparticles for Mass Spectrometric Immunoassay.

High-throughput and sensitive detection of proteins are essential for clinical diagnostics and biomarker discovery. We develop a novel high-throughput, multiplexed, sensitive mass spectrometric (MS) immunoassay method, which utilizes antibody-modified phospholipid bilayer coated gold nanoparticles (PBL-AuNPs) as the detection label and antibody-immobilized magnetic beads as the capture reagent. This method enables magnetic enrichment of the PBL-AuNPs label specific to target protein, allowing sensitive surface enhanced laser desorption ionization (SELDI)-TOF MS detection of the protein via its specific label. AuNPs act as not only the support but also the matrix for the phospholipids in SELDI TOF MS detection. Moreover, with phospholipids with varying molecular weights as the encoded MS reporters, this method allows multiplexed detection of multiple proteins. With the use of a predefined phospholipids internal standard, this method also affords excellent reproducibility in protein quantification. We have demonstrated this method using the assays of two tumor biomarkers, and the results reveal that it provides a sensitive platform for multiplexed protein detection with detection limits in the picomolar ranges. This method may provide a useful platform for high-throughput and sensitive detection of protein biomarkers for clinical diagnostics.