Asymmetric vesicles are valuable for understanding and mimicking cell and practical biomedicine applications. Recently, a very straightforward methodology for fabricating asymmetric polymersome was developed by Lodge’s group through the coassembly of polystyrene-b-poly(ethylene oxide) (PS-b-PEO) and polybutadiene-b-poly(ethylene oxide) (PB-b-PEO) block copolymers at the interface of a polystyrene/polybutadiene/chloroform (PS/PB/CHCl3) emulsion. However, the in-depth microscopic mechanism for the formation of asymmetric polymersomes remains unclear. To address this issue, in this article, the coassembly process for the formation of the asymmetric polymersomes in Asano’s experimental system was systematically investigated by employing a dissipative particle dynamics (DPD) simulation. Our results definitely demonstrate the formation of the asymmetric polymersomes such as that in the experiments and that the bilayer formed through the folding and crossing of the PEO blocks. Besides, from the microscopic view, three stages can be discerned in the formation process: (1) the formation of micelles, (2) the micelle diffusion to the interface, and (3) the micelle rearrangement at the interface to form an asymmetric polymersome. Meanwhile, the incompatibility among PS, PB, and PEO is proven to be the main driving force for asymmetric polymersome formation. Moreover, the effects of the order of addition of copolymers and the volume fraction of PEO blocks on the structure of the asymmetric polymersomes are also investigated. We find that the formation process is affected severely by the order of addition, and adding PS-b-PEO first can make the asymmetric bilayer more perfect. Not only that, but perfect asymmetric polymersomes can be formed only when the volume fraction of PEO (fPEO) is greater than 0.55. We believe the present work can extend the knowledge of the self-assembly of asymmetric polymersomes, especially with respect to the self-assembly mechanism.

This work reports a SO2 derivative-detecting and colorful hyperbranched polymeric ionic liquid (HBPIL) vesicle through aqueous self-assembly. By a simple anion-exchange, we achieved the combination of functional small-molecule probe of acid fuchsin with HBPILs. The obtained HBPIL vesicle displayed ultraviolet absorption at 544 nm, and was used as a novel SO2 derivative sensor with high sensitivity and visualization. Due to the functional ion pairs enriching on the surface, the SO32− detection limit of the HBPILs vesicles was as low as 0.138 μmol/L, which was about 1.5 orders of magnitude lower than that of acid fuchsin.

AbstractIn this paper, a kind of novel water-soluble chitosan-polydopamine (CHT-PDA) nanoparticles with a hydrodynamic diameter (Dh) around 10 nm were reported by the combination of self-polymerization of PDA and electrostatic complexation between PDA and CHT in water/DMSO (W/D) mixture at the molar fraction of DMSO (xDMSO = 0.37). The preparation method was efficient with a yield of 98% around. The as-prepared water-soluble CHT-PDA nanoparticles exhibited effective UV-screen ability, enhanced visible-light transmittance and good cytocompatibility via MTT assay, which might be used in transparent formulation for UV protection usage, especially in biological field including sun care application.

Self-assembly of amphiphilic hyperbranched multiarm copolymers (HMCs) has shown great potential for preparing all kinds of delicate supramolecular structures in all scales and dimensions in solution. However, theoretical studies on the influencing factors for the self-assembly of HMCs have been greatly lagging behind. The phase diagram of HMCs in selective solvents is very necessary but has not been disclosed up to now. Here, the self-assembly of HMCs with different hydrophilic fractions in various solvents was studied systematically by using dissipative particle dynamics (DPD) simulations. Three morphological phase diagrams are constructed and a rich variety of morphologies, ranging from spherical micelles, worm-like micelles, membranes, vesicles, vesosomes, small micellar aggregates (SMAs), and aggregates of spherical and worm-like micelles to helical micelles, are obtained. In addition, both the self-assembly mechanisms and the dynamic processes for the formation of these self-assemblies have been systematically investigated. The simulation results are consistent with available experimental observations. Besides, several novel structures, like aggregates of spherical and worm-like micelles, vesosomes and helical micelles, are firstly discovered for HMC self-assembly. We believe the current work will extend the knowledge on the self-assembly of HMCs, especially on the control of supramolecular structures and on fabricating novel self-assemblies.

The confinement effect of the β-barrel defines the emission profiles of the chromophores of the green fluorescent protein (GFP) family. Here, we describe the design strategy and mimicking of confinement effects via the chromophore itself, termed the self-restricted effect. By systematically tailoring the GFP core, a family of 2,5-dialkoxy-substituted GFP chromophore analogues is found to be highly emissive and show remarkable solvatofluorochromism in fluid solvents. Fluorescence quantum yield (QY) and lifetime measurements, in combination with theoretical calculations, illustrate the mechanism relying on inhibition of torsional rotation around the exocyclic CC bond. Meanwhile, theoretical calculations further reveal that the electrostatic interaction between the solvent and the imidazolinone oxygen can contribute to suppress the radiationless decay channel around the exocyclic C═C double bond. Our findings put forward a universal approach toward unlocked highly emissive GFPc analogues, potentially promoting the understanding of the photophysics and biochemical application of GFP chromophore analogues.

•Self-restricted oxazolone GFP chromophore is reported.•Inhibition of conformational motions enhances emission of oxazolone GFP chromophore.•Self-restricted oxazolone GFP chromophore is used as reaction-based probe.The β-barrel provides a confined environment for chromophores of the green fluorescent protein (GFP) family, defining their emission profiles by the chromophore/β-barrel interactions. Here, we describe the generation of self-restricted oxazolone GFP chromophore (GFPc) for construction of reaction-based fluorescent probe toward dopamine by mimicking the confinement effect of the β-barrel. Through standard synthetic method, the first self-restricted GFPc oxazolone analogue (MBDO) and the conventional pyrenyl-based chromophore (PDO) were prepared respectively. Under the same condition, MBDO shows much better emission response with fluorescent quantum yield (QY) over one order of magnitude higher than that of PDO due to the generation of the self-restricted effect. And, the fluorescent QY of MBDO reaches above 30% in dimethyl sulfoxide, which is the largest ever recorded for unlocked GFPc analogues in highly polar solvents. Moreover, theoretical calculations further reveal that the enhanced emission of MBDO is due to the inhibition of conformational motions around the exocyclic CC bonds. Combination the enhanced emission and the reactivity of the lactone, MBDO is applied to construct reaction-based fluorescent probe toward dopamine via a ring-opening reaction of the lactone. Prospectively, the destruction of the oxazolone would break the effective conjugated structure of the chromophore, which can decrease the corresponding fluorescence. This work puts forward a novel approach to generate highly emissive GFPc oxazolone analogue, which can be used to fabricate reaction-based fluorescent probe toward dopamine, potentially promoting the biochemical applications using synthetic GFP chromophore analogues.Download high-res image (222KB)Download full-size image