We present a novel, versatile, and simple solution-based routine to produce soft, nanosized Janus particles with tunable structural and physical properties at high volume yield. This process is based on the cross-linking of compartments within precisely defined multicompartment micelles (MCMs), which are themselves formed by the self-assembly of ABC triblock terpolymers. Therein, the C blocks form the stabilizing corona emanating from B compartments, which in turn reside on an A core. Cross-linking of the B compartments allows to permanently fixate the phase-separated state and dissolution in a good solvent for all blocks breaks up the MCMs into single Janus particles. They now consist of a core of cross-linked B blocks and two phase-separated hemispheres of A and C. The process gives access to unprecedented structural features such as tunable core diameter and control over the Janus balance ranging from dominant A side to equal hemispheres to dominant C side. We demonstrate that this simple one-pot approach can be extended to a range of triblock terpolymers with different block lengths and block chemistries to furnish a library of tailor-made Janus particles with widely tunable physical properties. Such a diversity and simplicity has remained unreachable with our previously developed approach using the controlled cross-linking of bulk morphologies. We show that this new synthetic route can be upscaled to a high volume yield of 10 wt %, thereby enabling large-scale applications. We further demonstrate the effect of the Janus balance on colloidal self-assembly. Janus particles with a dominant hydrophobic and a small hydrophilic patch aggregate into large clusters in water, but merely di- or trimerize in chloroform. 相似文献
In this paper, a straightforward method to produce poly(3‐hydroxyalkanoate)‐based multicompartment micelles (MCMs) is presented. Thiol‐ene addition is used to graft sequentially perfluorooctyl chains and poly(ethylene glycol) oligomers onto poly(3‐hydroxyoctanoate‐co‐hydroxyundecenoate) oligomers backbone. Well‐defined copolymers are obtained as shown by 1H NMR and size‐exclusion chromatography. After nanoprecipitation in water, novel PHA‐based MCMs are evidenced by cryo‐transmission electron microscopy. Moreover, the cytocompatibility of MCMs is demonstrated in vitro via cell viability assay. 相似文献
Fluorogenic nanoparticles (NPs) able to sense different physiological environments and respond with disaggregation and fluorescence switching OFF/ON are powerful tools in nanomedicine as they can combine diagnostics with therapeutic action. pH-responsive NPs are particularly interesting as they can differentiate cancer tissues from healthy ones, they can drive selective intracellular drug release and they can act as pH biosensors. Controlled polymerization techniques are the basis of such materials as they provide solid routes towards the synthesis of pH-responsive block copolymers that are able to assemble/disassemble following protonation/deprotonation. Ring opening metathesis polymerization (ROMP), in particular, has been recently exploited for the development of experimental nanomedicines owing to the efficient direct polymerization of both natural and synthetic functionalities. Here, we capitalize on these features and provide synthetic routes for the design of pH-responsive fluorogenic micelles via the assembly of ROMP block-copolymers. While detailed photophysical characterization validates the pH response, a proof of concept experiment in a model cancer cell line confirmed the activity of the biocompatible micelles in relevant biological environments, therefore pointing out the potential of this approach in the development of novel nano-theranostic agents.pH-responsive micelles disassembly, upon acidification during lysosomal uptake, leads to fluorescence switch ON. These nanoparticles are promising candidates for the design of novel stimuli-responsive drug delivery systems.相似文献
Using dissipative particle dynamics simulation, structural evolution from concentric multicompartment micelles to raspberry-like multicompartment micelles self-assembled from linear ABC triblock copolymers in selective solvents was investigated. The structural transformation from concentric micelles to raspberry-like micelles can be controlled by changing either the length of B blocks or the solubility of B block. It was found that the structures with B bumps on C surface (B-bump-C) are formed at shorter B block length and the structures with C bumps on B surface (C-bump-B) are formed at relative lower solubility of B blocks. The formation of B-bump-C is entropy-driven, while the formation of C-bump-B is enthalpy-dominated. Furthermore, when the length of C blocks is much lower than that of B blocks, an inner-penetrating vesicle was discovered. The results gained through the simulations provide an insight into the mechanism behind the formation of raspberry-like micelles. 相似文献
Dissipative particle dynamics simulations were performed on multicompartment micelles formed by blending star and linear triblock copolymers, in which the influences of blending options and blending ratio as well as copolymer chain compositions were studied systematically. The results show that blending of copolymers with different architectures is a promising strategy to control the morphology and structure of multicompartment micelles. This work revealed several new morphologies of multicompartment micelles by blending star and linear triblock copolymers, and the dynamic processes were elucidated at the molecular level by tracing the motions of copolymer chains. The results of this work provide deep insight into micro/mesoscopic details of the underlying mechanisms, contributing to a more complete understanding of multicompartment micelle formation and structural control. 相似文献
A simple and effective route to design pH-responsive viscoelastic wormlike micelles based on commercial compounds is reported. According to this route, pH-sensitive viscoelastic fluids can be easily obtained by introducing a pH-responsive hydrotrope into a surfactant solution. In this paper, the mixed system of cetyltrimethylammonium bromide (CTAB) and potassium phthalic acid (PPA) was studied in detail. This pH-sensitive fluid can be switched between a gellike state and a waterlike state within a narrow pH change. Rheology and DLS results revealed that the pH-sensitive flowing behavior was attributed to the microstructure transition between wormlike micelles and short cylindrical micelles. Combined with fluorescence anisotropy, NMR, and UV–vis, it was demonstrated that the pH response of viscoelastic fluid originated from the different binding abilities of hydrotrope to surfactant as pH varies. Furthermore, different kinds of hydrotropes can be utilized to prepare pH-responsive viscoelastic fluids in the desired pH areas. 相似文献
pH-Responsive DNA assembles have drawn growing attentions owing to their great potential in diverse areas.However,pH-responsive motifs are limited to specific DNA sequences and annealing is usually needed for DNA assemblies;therefore,sequence-independent pH-responsive DNA assembly at room temperature is highly desired as a more general way.Here,we propose a reversible pH-responsive DNA assembly strategy at room-temperature using zwitterion,glycine betaine(GB),as charge-regulation molecules.The reversible assembly and disassembly of DNA nanostructures could be achieved by alternatively regulating the acidic and basic environments in the presence of GB,respectively.In an acidic environment,carboxylate group in GB was protonated and GB was positively charged,which facilitated to shield the inherent electrostatic repulsion of DNA strands.Molecular simulation showed that the newly formed carboxyl group in protonated GB could form hydrogen bonds with bases in DNA to promote the assembly of DNA strands.In a basic solution,carboxylate group in GB was deprotonated and GB was neutral,thus inducing the dissociation of DNA assembly. 相似文献
The well-established ability of copolymer micelles to encapsulate and release hydrophobic molecules has been investigated following their adsorption onto silica particles. Here, a pH-responsive copolymer, poly(2-(dimethylamino)ethyl methacrylate)- b-poly(2-(diethylamino)ethyl methacrylate) (PDMA(106)- b-PDEA(25)), has been used to study the formation and dissociation of adsorbed micelles through pH variation. This copolymer behaves as free unimers in aqueous solutions below pH 8 and forms micelles 29 nm in hydrodynamic diameter above this pH. Encapsulation and release of a model hydrophobic compound (pyrene) by in situ adjustment of the solution pH has been compared for both free and adsorbed micelles using fluorescence spectrophotometry, epifluorescence microscopy, and zeta potential measurements. At basic pH values, pyrene is solubilized within the cores of micelles adsorbed on silica particles: addition of acid leads to micelle dissociation and release of the pyrene into the bulk aqueous solution. Micelle adsorption does not appear to hinder the extent of pyrene uptake/release. Moreover, this pH-responsive behavior is both reversible and reproducible over multiple pH cycles. 相似文献
Numerous nanocarriers with excellent biocompatibilities have been used to improve cancer therapy. However, nonspecific protein adsorption of nanocarriers may block the modified nanoparticles in tumor cells, which would lead to inefficient cellular internalization. To address this issue, pH-responsive polyurethane prodrug micelles with a zwitterionic segment were designed and prepared. The micelle consisted of a zwitterionic segment as the hydrophilic shell and the drug Adriamycin (DOX) as the hydrophobic inner core. As a pH-responsive antitumor drug delivery system, the prodrug micelles showed high stability in a physiological environment and continuously released the drug under acidic conditions. In addition, the pure polyurethane carrier was demonstrated to be virtually non-cytotoxic by cytotoxicity studies, while the prodrug micelles were more efficient in killing tumor cells compared to PEG-PLGA@DOX. Furthermore, the DOX cellular uptake efficiency of prodrug micelles was proved to be obviously higher than the control group by both flow cytometry and fluorescence microscopy. This is mainly due to the modification of a zwitterionic segment with PU. The simple design of zwitterionic prodrug micelles provides a new strategy for designing novel antitumor drug delivery systems with enhanced cellular uptake rates. 相似文献
Self-assembly between oppositely charged polyelectrolytes conjugated to neutral polymeric blocks form polyelectrolyte complex (PEC) micelles. These nanostructures have gained significant interest in the field of nucleic acid and protein delivery, along with emerging applications in biosensing and catalysis. These carriers are highly modular systems, with the ability to engineer stimuli-responsive and targeting properties, making them smart platforms for biomedical applications. In this review, we discuss the current understanding of mechanisms involved in the assembly and disassembly of these nanoparticles, and the structural and functional changes as a response to solution conditions. We also discuss the latest and most impactful applications of PEC micellar systems in the biomedical field, with far-reaching influence on the treatment of various human diseases. 相似文献
Theranostic hyaluronic acid (HA) prodrug micelles with pH-responsive drug release and aggregation-induced emission (AIE) properties were prepared by chemical graft of biomimetic phosphorylcholine (PC), anticancer drug doxorubicin (DOX) and AIE fluorogen tetraphenylene (TPE) to the HA backbone. DOX was conjugated to the HA backbone by a hydrazone bond which can be hydrolyzed under acidic environment and result in pH-triggered smart release of DOX. The TPE units with typical AIE characteristics were applied for real time drug tracking in cancer cells. The HA-based prodrugs could self-assemble into micelles in aqueous solution as confirmed by the dynamic light scattering (DLS) and transmission electron microscopy (TEM). The intracellular distribution of HA prodrug micelles could be clearly observed by fluorescence microscopy based on the strong fluorescence of TPE. Moreover, after treated with the micelles, stronger fluorescence of TPE in CD44 overexpressed MDA-MB-231 cancer cells was observed, compared to the CD44 negative cell line, NIH3T3 cells, suggesting efficient cell uptake of HA prodrug micelles by receptor-mediated endocytosis. The cell viability results indicated that the prodrug micelles could inhibit the proliferation of the cancer cells effectively. Such pH-triggered theranostic drug delivery system with AIE features can provide a new platform for targeted and image-guided cancer therapy. 相似文献
Supramolecular self-assemblies in selective solvents give rise to many patterning possibilities. The diblock copolymer polystyrene-b-poly(4-vinylpyridine) (PS-P4VP) is one such polymer that self-assembles into neat nanostructures in toluene. These nanostructures once formed are highly susceptible to solvent influence. Unfortunately, for use as nanotemplates and in the synthesis of nanoparticles, the susceptibility of the films to solvents can be a problem. In this study, we present a method to stabilize the structures through chemical means in solution. We used 1,4-dibromobutane in solution to chemically crosslink the pyridine residues of each of PS-P4VP to yield a series of stable spherical aggregates. In this way, the cross-linking ratio can be precisely controlled. The solution properties were studied using dynamic light scattering and small angle X-ray scattering and the morphology of the resulting micellar film was studied using transmission electron microscopy (TEM). The size of the micelles formed was found to be dependent on the amount of cross-linking and the shape of the PS-P4VP micelles remains stable when exposed to a selective solvent for PS. 相似文献
Several new multicompartment micellar structures have been identified by cryogenic transmission electron microscopy (cryoTEM) from the aqueous self-assembly of mu-[poly(ethylethylene)][poly(ethylene oxide)][poly(perfluoropropylene oxide)] (mu-EOF) miktoarm star terpolymers. This work extends our previous studies, in which it was found that, upon decreasing the length of the hydrophilic block (O), the resulting micelles evolved from "hamburger" micelles to segmented worms and ultimately to nanostructured bilayers and vesicles. In the terpolymers examined here segmented ribbons and bilayers were found at an intermediate composition between segmented worms and nanostructured bilayers, provided that the fluoropolymer (F) was the minority component in the micelle core. On the other hand, when the F block exceeded the chain length of the hydrocarbon block (E), the superhydrophobic F block imposed a "double frustration" on the self-assembly of the mu-EOF(2-9-5) terpolymer; while F prefers to minimize its interfacial contact with the O corona, it must occupy the majority of the micellar core. Therefore, a richer variety of multicompartment micelles, including well-defined segmented worms, raspberry-like micelles, and multicompartmentalized worms, were formed from one terpolymer, as revealed by cryoTEM. Despite the complexity and variety of the observed aggregate morphologies, a small number of common structural elements can be invoked to interpret the observed micelles and to relate a given structure to the terpolymer composition. 相似文献
Multicompartment micelles are a new class of nanomaterials that may find wide applications in the fields of drug delivery, nanotechnology and catalysis. Due to their structural complexity, as well as the wide parameter space to explore, experimental investigations are a difficult task, to which molecular simulation may contribute greatly. In this paper, the application of the dissipative particle dynamics simulation technique to the understanding of multicompartment micelles is introduced, illustrating that DPD is a powerful tool for identifying new morphologies by varying block length, block ratio and solvent quality in a systematic way. The formation process of multicompartment micelles, as well as shear effects and the self-assembly of nanoparticle mixtures in multicompartment micelles, can also be studied well by DPD simulation. The present work shows that DPD, as well as other simulation techniques and theories, can complement experiments greatly, not only in exploring properties in a wider parameter space, but also by giving a preview of phenomena prior to experiments. DPD, as a mesoscopic dynamic simulation technique, is particularly useful for understanding the dynamic processes of multicompartment micelles at a microscopic level.
In this Article, we have investigated the self-assembly of a series of amphiphilic hyperbranched star-block copolymers to form multicompartment micelles in acidic aqueous solution (pH 3.0) or in a dimethylformamide/water (pH 3.0) mixture. These hyperbranched star-block copolymers were prepared via oxyanion-initiated polymerization process, using hydroxyl-terminated hyperbranched poly[3-ethyl-3-(hydroxymethyl)oxetane] (HP) as a macroinitiator precursor with multi-reactive sites. It was turned into oxyanion end-capped macroinitiator through the reaction with potassium hydride, and followed by a sequential addition of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA) and 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate (OFPMA). The resultant HP-star-PDMAEMA-b-POFPMA copolymers were characterized via 1H NMR, 19F NMR, and gel permeation chromatography (GPC). The analyses of transmission electron microscopy (TEM), dynamic light scattering (DLS), and microelectrophoresis confirmed that these copolymers could directly self-organize into supramolecular multicompartment micelles with different diameters, depending on the length of the PDMAEMA segment, which can be protonated in acidic aqueous medium. The measurement of the zeta potential gave further evidence of the aggregating structures for the multicompartment micelles. 相似文献
Summary: Dissipative particle dynamics simulations are performed on the distributions of two agents in a core‐shell‐corona multicompartment micelle. The simulated results show that when the agents are weakly hydrophobic, their distributions in the multicompartment micelle are largely affected by the interactions between the agents and the blocks; while for strongly hydrophobic agents, the self‐assembly of solubilized species in the micelle is also affected largely by the interactions between the species. This work confirms that a multicompartment micelle can store two agents within separate nanoscopic compartments simultaneously, and shows that the distributions of the agents can be tailored easily by changing the interactions presented. This provides molecular‐level information that is useful for the future rational design of new micellar systems with tailored properties.
Simulated cross sections of the multicompartment micelles with strongly hydrophobic solubilized agents (the solvent and block A are omitted for clarity, block B is dark gray, block C is light gray, agent P is white, and agent Q is black). 相似文献