AbstractIt is challenging to prepare co-organized nanotube systems with controlled nanoscale chirality in an aqueous liquid flow field. Such systems are responsive to a bubbled external gas. A liquid vortex induced by bubbling carbon dioxide (CO2) gas was used to stimulate the formation of nanotubes with controlled chirality; two kinds of achiral cationic building blocks were co-assembled in aqueous solution. CO2-triggered nanotube formation occurs by formation of metastable intermediate structures (short helical ribbons and short tubules) and by transition from short tubules to long tubules in response to chirality matching self-assembly. Interestingly, the chirality sign of these assemblies can be selected for by the circulation direction of the CO2 bubble-induced vortex during the co-assembly process.

AbstractIt is challenging to prepare co-organized nanotube systems with controlled nanoscale chirality in an aqueous liquid flow field. Such systems are responsive to a bubbled external gas. A liquid vortex induced by bubbling carbon dioxide (CO2) gas was used to stimulate the formation of nanotubes with controlled chirality; two kinds of achiral cationic building blocks were co-assembled in aqueous solution. CO2-triggered nanotube formation occurs by formation of metastable intermediate structures (short helical ribbons and short tubules) and by transition from short tubules to long tubules in response to chirality matching self-assembly. Interestingly, the chirality sign of these assemblies can be selected for by the circulation direction of the CO2 bubble-induced vortex during the co-assembly process.

Understanding the effect of ionic strength on the efficiency of this enzyme cascade within charged hierarchical nanospace is not only fundamentally interesting, but also important for translating biochemical pathways to noncellular environments. We herein report ionic strength-modulated efficiency for the enzyme cascade (glucose oxidase (GOx) and horseradish peroxidase (HRP)) within the dendritic polyethylene-cationic poly(p-phenylene ethynylene) (DPE-PPE+) biocompatible scaffold. The largest enhancement in activity is observed for DPE-PPE+/GOx/HRP system with adding simple salt sodium chloride (0.9 M), which is almost 3 times higher than the corresponding control without the addition of salt. A decrease in the transient time is experimentally observed in DPE-PPE+/GOx/HRP system with increasing salt concentration from 0 M to 0.9 M, being in good agreement with the salt-regulated efficiency results. The cationic conjugated PPE+ shell of DPE-PPE+ is employed as a probe to monitor the ionic strength-modulated electrostatic shielding effects, which has influence on the enzyme release and enzymatic activity for the DPE-PPE+/GOx/HRP.

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+.

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.

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.

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.

From the temperature dependent steady-state and time-resolved fluorescence studies of coumarin 153 (C153) in dendritic polyethylene (DPE)–poly(oligo(ethylene gylcol) methacrylate) (POEGMA) unimolecular micelles, the polarity and microviscosity of the microenvironments of DPE–POEGMA were obtained. The analysis of the steady-state emission suggested that C153 sensed a more polar microenvironment in dendrimer polyethylene (dPE)–POEGMA than that in hyperbranched polyethylene (hPE)–POEGMA. It is found that the microviscosity around C153 in DPE–POEGMA micelle could be predicted from the measured reorientational time, which was observed to decrease with increasing temperature, and that local friction experienced by C153 in dPE–POEGMA decreases faster than in hPE–POEGMA with the increase of temperature, although both have similar local friction ranges.

The phase-transition behavior of unimolecular dendritic polyethylene amphiphiles with core−shell architecture aqueous solutions was investigated by a Rayleigh scattering (RS) technique. Dendritic polyethylene (DPE)-poly(oligo(ethylenegylcol) methacrylate) (POEGMA) with a DPE hydrophobic core and a POEGMA hydrophilic shell was synthesized by the atom-transfer radical polymerization (ATRP) of OEGMA using DPE terminated by the bromine group as a macroinitiator. The fluorescence measurements implied that DPE-POEGMA molecules in aqueous solutions existed as the unimolecular micelles. To understand the phase-transition behavior of dendritic polyethylene amphiphilic unimolecular micelles in aqueous solutions, the temperature dependence of the RS spectra of DPE-POEGMA aqueous solutions under the heating-and-cooling cycle indicated that the heating and cooling processes were reversible but hysteresis existed. The phase transition of DPE-POEGMA aqueous solutions decelerated with increasing levels of PEGylation. DPE-POEGMA exhibited a lower phase-transition temperature in D2O than in water.

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+.

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.

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.