Elongation flow-triggered morphology transitions of dendritic polyethylene amphiphilic assemblies: host-guest implications.

The assemblies and transformations of dendritic polyethylene (DPE)-poly(oligo(ethyleneglycol) methacrylate) (POEGMA) amphiphilic micelles have been demonstrated by cryo-TEM and DLS techniques under elongation flow stimuli. The flow rate-dependence of the dissymmetry ratio suggests the possibility that a combination of shear and elongation could also be responsible for the transitions of DPE-POEGMAs, but it is obvious that the exposure of elongation flow is essential and plays a key role in the assembly and fusion of the DPE-POEGMA micelles. Fluorescence resonance energy transfer (FRET) is used to provide insight into the assembly and fusion of DPE-POEGMA under elongation flow. The FRET results show that a shorter separation distance of DiO-DiI with higher elongation rate can result in higher FRET efficiency. Furthermore, DPE-POEGMAs can display the responsive switching ability of the elongation flow-triggered FRET.

Effects of channel morphology on nitrate retention in a headwater agricultural stream in Lake Chaohu Basin, China.

Five field tracer experiments and relevant detailed investigations of physical characterizations were conducted to investigate the effects of channel geomorphic settings on nitrate uptake efficiency on a 310-m long geomorphically distinct stream reach in a headwater agricultural stream in Hefei District, Lake Chaohu Basin. The model-fitted parameters from the one-dimensional transport with inflow and storage model were used to estimate the transient storage metric ([Formula: see text]) and determine the total nitrate uptake coefficient (k) for the study reach. And then, a nutrient spiraling approach was applied to reach-scale nitrate uptake estimates (Sw, Vf, and U). The results showed that the main channel was the major contributor to nitrate uptake retention, and the higher geomorphic complexity might result in better nitrate uptake efficiency. The partial least squares regression (PLSR) analysis showed strong correlations between the independent variables as geomorphic settings, Reynolds number and transient storage, and the dependent variables as nitrate uptake metrics, which further underscored the importance of stream physical characteristics on measurement of stream nitrate uptake.

[Nitrate Uptake Kinetics and Correlation Analysis in an Agricultural Drainage Ditch].

To investigate the whole-reach nitrate (NO3--N) uptake dynamics in a headwater agricultural stream, we performed five pulse tracer additions of a reactive solute (as KNO3) and a conservative solute (as NaBr) in an agricultural drainage ditch in Hefei district, Chaohu Lake basin, from October 2016 to April 2017. The TASCC (tracer additions for spiraling curve characterization) approach and Michaelis-Menten (M-M) method were applied for the simulation of NO3--N uptake dynamics. Results showed that the ambient areal rate of total NO3--N uptake Uamb varied from 11.40 to 69.13 µg ·(m2 ·s)-1 with an average of 34.45 µg ·(m2 ·s)-1, and the ambient uptake velocity Vf-amb averaged 0.24 mm ·s-1 and varied from 0.07 to 0.43 mm ·s-1 across three well-mixed sub-reaches in the study. The ambient uptake length Sw-amb averaged 199.06 m with a range from 92.51 to 405.74 m, which was much smaller than the length of the drainage ditch (about 2.5 km), suggesting that the agricultural drainage ditch had a high potential for NO3--N retention. Generally, the M-M model fit the NO3--N uptake dynamics well, and the maximum uptake Umax ranged from 158 to 1280 µg ·(m2 ·s)-1 with a mean of 631.13 µg ·(m2 ·s)-1. The half saturation constant Km ranged from 0.16 to 5.52 mg ·L-1 with a mean of 1.46 mg ·L-1. According to correlation analysis, Sw-amb was negatively correlated with NO3--Namb, and Uambwas significantly positively correlated with NO3--Namb, while other nutrient spiraling metrics were not correlated with the NO3--N ambient concentration. Hydrological conditions had no distinct effect on the NO3--N retention, but both the width variability Фw and variability in cross-sectional area ФA were significantly correlated with most of the nutrient spiraling metrics, indicating that geomorphic features in the drainage ditch evidently impacted NO3--N uptake.

Functionalization of cationic poly(p-phenylene ethynylene) with dendritic polyethylene enables efficient DNAzyme delivery for imaging Pb2+ in living cells.

We report here an effective Pb2+-dependent DNAzyme (8-17 DNAzyme) delivery system based on the water-soluble dendritic polyethylene-cationic poly(p-phenylene ethynylene) for successfully imaging Pb2+ in living cells. For utilizing the 8-17 DNAzyme and its unique ability to catalyze a phosphodiester bond cleavage reaction in the presence of Pb2+, the distinctive conjugated polymer-based polyvalent nanocarrier design manages to load and transport 8-17 DNAzyme across cell membranes, and to realize the fluorescence imaging of Pb2+ in living cells. As shown by the confocal microscopy and flow cytometry observations, the fluorescence of Cy5.5 is obviously activated under the conditions of incubation with Pb2+, compared with the absence of Pb2+. Taken together, the study demonstrates the combination of the molecular-wire effect with "dendrimer effects" on their effective DNAzyme delivery and their cellular imaging Pb2+.

Conjugation of cationic poly(p-phenylene ethynylene) with dendritic polyethylene enables live-cell imaging.

A new system based on dendritic polyethylene-cationic poly(p-phenylene ethynylene) core-shell nanoparticles was developed for live-cell imaging. By using the combination of molecular-wire and "dendritic effects" strategies, this design provides the new system with higher photoluminescence quantum yields, lower cell viability and better cellular permeability compared with free cationic poly(p-phenylene ethynylene), allowing it to exhibit remarkable improvements in fluorescence imaging for live cells.

Functionalization of dendritic polyethylene with cationic poly(p-phenylene ethynylene) enables efficient siRNA delivery for gene silencing.

A novel system based on a dendritic polyethylene-cationic poly(p-phenylene ethynylene) polyvalent nanocarrier was developed for siRNA delivery. By using the combination of a molecular wire and a "dendritic effects" strategy, this design provides the nanocarrier system with low cytotoxicity, cellular imaging and high siRNA delivery efficiency, allowing it to exhibit remarkable gene knockdown abilities as well as real-time monitoring of the siRNA delivery process.