Controlling the orientation and long‐range order of nanostructures is a key issue in the self‐assembly of block copolymer micelles. Herein, a versatile strategy is presented to transform one‐component oxime‐based block copolymer micelles into long‐range ordered dense nanopatterns. Photoisomerization provides a straightforward and versatile approach to convert the hydrogen‐bonding association from inward dimerization (E‐type oxime motifs, slightly desolvated in ethyl acetate) into outward interchain association (Z‐type ones, highly desolvated in ethyl acetate). This increases the glass transition temperature in bulk and converts swollen micelles into compact spherical micelles in solution. The reconstruction of these micelles on various substrates demonstrates that the phase transformation enables reconstruction of spherical micelles into mesoscopic sheets, nanorods, nanoworms, nanowires, networks, and eventually into long‐range ordered and densely packed textile‐like and lamellar nanopatterns on a macroscopic scale by adjusting E/Z‐oxime ratio and solvent‐evaporation rate.
A pH‐responsive free‐blockage release system was achieved through controlling the hydrophobic/hydrophilic conversion of mesoporous silica nanopores. This system further presented pulsatile release with changing pH values between 4.0 and 7.0 for several cycles. This free‐blockage release system could also release antitumor agents to induce cell death after infecting tumor cells and could have the ability of continuous infection to tumor cells with high drug‐delivery efficiency and few side effects. 相似文献
Summary: The complexation between polystyrene‐block‐poly(acrylic acid) (PS‐b‐PAA) micelles and poly(ethylene glycol)‐block‐poly(4‐vinyl pyridine) (PEG‐b‐P4VP) is studied, and a facile strategy is proposed to prepare core‐shell‐corona micellar complexes. Micellization of PS‐b‐PAA in ethanol forms spherical core‐shell micelles with PS block as core and PAA block as shell. When PEG‐b‐P4VP is added into the core‐shell micellar solution, the P4VP block is absorbed into the core‐shell micelles to form spherical core‐shell‐corona micellar complexes with the PS block as core, the combined PAA/P4VP blocks as shell and the PEG block as corona. A model is suggested to characterize the core‐shell‐corona micellar complexes.
Schematic formation of core‐shell‐corona (CSC) micellar complexes by adsorption of PEG‐b‐P4VP into core‐shell PS‐b‐PAA micelles. 相似文献
A new controlled release polymer micelle was designed and synthesized based on the concept of the “AND” logic with two orthogonal molecular triggers, namely pH and reduction, for intracellular drug delivery. Specifically, a hydrazine functionalized PEO‐b‐PMAA block copolymer was used to attach adriamycin (ADR) through the formation of hydrazone, then the as‐prepared ADR‐conjugated block copolymer micelles could be crosslinked by dithiodiethanoic acid. ADR was found to release most efficiently under both the low pH and the reductive conditions. This smart device is therefore equipped with two triggers with the “AND” logic for the releasing action, which is suitable for more complicated physiological conditions because the “ON” state is only realized under the simultaneous presence of the dual signal stimuli.
Once around the block : Incorporation of a rigid hydrogen‐bonding benzamide unit, placed at the interface between two polymer blocks, in poly(ethylene glycol) (PEG)–(thio)urea–poly(L ‐lactide) (PLLA) block copolymers transforms the morphology of the block copolymers, from spherical micelles, as formed by PEG‐PLLA diblock copolymers, into nanotubes in solution.
Although high‐boiling non‐solvent induced macrophase separation in emulsion droplets has been widely applied for the fabrication of polymeric capsules, precise control of their structures remains a great challenge. Herein, block copolymer capsules with tunable shell structures were fabricated by employing a non‐solvent as a liquid template in emulsion droplets. The properties of the non‐solvents dictate the phase separation sequence in the droplets and the capsule formation mechanism. Two different pathways for capsule formation were observed, and could be applied to predict the shell structure. The structured capsules could be transformed into mesoporous capsules, which demonstrated an intriguing structure‐dependent release behavior. Capsules with spherical shell structures displayed the best permeability, while those with lamellar shell structures showed the slowest release, but with a stepwise profile. After loading with an anticancer drug, different capsules induced different apoptosis ratios in cancer cell studies. 相似文献
Various biological behaviors are fueled by “respiration”, which is an example of catabolism. So far, we have reported various self‐oscillating soft materials exhibiting bioinspired dynamic movements. These autonomous polymer systems are driven by the Belousov–Zhabotinsky (BZ) reaction, which is analogous to the tricarboxylic acid (TCA) cycle that is an integral part of respiration. However, in the BZ reaction, the external addition of an oxidizing agent is necessary to initiate the oxidation process, which is realized by intracellular moieties such as ubiquinone in living systems. Herein, we realized self‐oscillating micelles that are driven without the external addition of an oxidizing agent. This was achieved by embedding the oxidizing source into the structure of the self‐oscillating AB diblock copolymers. This strategy introduces a new function equivalent to intracellular oxidizing moieties, and is useful for the design of completely autonomous bioinspired materials. 相似文献
Precise control over the morphology and dimensions of block copolymer (BCP) micelles has attracted interest due to the potential of this approach to generate functional nanostructures. Incorporation of liquid crystalline (LC) block can provide additional ways to vary micellar morphologies, but the formation of uniform micelles with controllable dimensions from LC BCPs has not yet been realized. Herein, we report the preparation of monodisperse cylindrical micelles with a LC poly(2‐(perfluorooctyl)ethyl methacrylate (PFMA) core via a fragmentation‐thermal annealing (F‐TA) process, resembling the “self‐seeding” process of crystalline BCP micelles. The average length of the cylinders increases with annealing temperature, with a narrow length distribution (Lw/Ln<1.1). We also demonstrate the potential application of the cylinders with LC cores as a cargo‐carrier by the successful incorporation of a hydrophobic fluorescent dye tagged with a fluorooctyl group. 相似文献
Multicompartment micelles (MCPs), comprising sequences of repeated elemental discoid parts connected by fasciculus, were formed by self‐assembly of polystyrene‐block‐poly(2‐vinyl pyridine)‐block‐poly(ethylene oxide). Using an electrostatic field, the MCPs can be disassembled through consequent release of small spherical micelles. During this disassembly process, release of loaded species can be achieved from the micelles in chronological order. Two location‐selected cargos (mitoxantrone (MTNT) and fluorescein isothiocyanate (FITC)) in the outer and inner compartments of the micelles can be released in chronological order. Under the applied electrostatic field (intensity: 16 kV cm?1), the loaded MTNT was rapidly released with more than 80 % release, whereas the loaded FITC was slowly released with less than 20 % release in 12 h. At a later stage (after more than 12 h), the loaded MTNT was slowly released with less than 20 % release, while the loaded FITC was rapidly released with more than 80 % release. 相似文献
In this contribution, amphiphilic star copolymers (H40‐star‐PCL‐a‐PEG) with an H40 hyperbranched polyester core and poly(ε‐caprolactone)‐a‐poly(ethylene glycol) copolymer arms linked with acetal groups are synthesized using ring‐opening polymerization and a copper (I)‐catalyzed alkyne‐azide cycloaddition click reaction. The acid‐cleavable acetal groups between the hydrophilic and hydrophobic segments of the arms endow the amphiphilic star copolymers with pH responsiveness. In aqueous solution, unimolecular micelles can be formed with good stability and a unique acid degradability, as is desirable for anticancer drug carriers. For the model drug of doxorubicin, the in vitro release behavior, intracellular release, and inhibition of proliferation of HeLa cells show that the acid‐cleavable unimolecular micelles with anticancer activity can be dissociated in an acidic environment and efficiently internalized by HeLa cells. Due to the acid‐cleavable and biodegradable nature, unimolecular micelles from amphiphilic star copolymers are promising for applications in intracellular drug delivery for cancer chemotherapy.
Hollow molecular imprinted polymer microspheres were prepared by distillation precipitation polymerization with (S)‐(+)‐ibuprofen (S‐IBF) as template molecule and acrylamide (AM) as functional monomer. Using the silicon dioxide (SiO2, 180 nm) modified by 3‐(trimethoxysilyl)propyl methacrylate (MPS) as the template microspheres, the molecular imprinted shells were coated on successfully (SiO2@MIPs). The thermosensitive SiO2@MIPs‐PNIPAM core‐shell microspheres were subsequently prepared by grafting the PNIPAM chains (Mn=1.21×104 g/mol, polydispersity index=1.30), which were prepared by reversible addition‐fragmentation chain transfer (RAFT) polymerization, on the surface of SiO2@MIPs microspheres via the thiol‐ene click chemistry. The grafting density of PNIPAM brushes on the SiO2@MIPs microspheres was about 0.18 chains/nm2. After HF etching, the hollow imprinted microspheres were finally obtained. For thermosensitivity analysis, the phase transition temperatures of multifunctional nanoparticles were measured by DSL at 25°C and 45°C respectively, and the sizes of the microspheres changed by about 35 nm. The modified microspheres presented excellent controlled release property to S‐IBF, moreover about half amount of the adsorptions passed into acetonitrile‐water solution through the specific holes of imprinted shell at 25°C under vibration. 相似文献
Hybrid cylindrical micelles loaded with nanoparticles are fabricated via extrusion of spherical micelles in solution phase through small long cylindrical pores. Small gold nanoparticles (AuNPs) are pre‐coated with thiol‐terminated polystyrene and then further encapsulated in the core part of block copolymer spherical micelles by a precipitation method. By varying the starting mass ratio of AuNPs and the diblock copolymers polystyrene‐b‐polyisoprene (PS‐b‐PI) during the encapsulation, the AuNPs loading density along the cylindrical micelles can be controlled. The mechanism for this sphere‐to‐cylinder transition induced by extruding hybrid spherical micelles through small cylindrical nanopores is discussed. These findings provide a novel way to manufacture high‐quality and functional polymeric nanowires, which may open the door to new applications such as in plasmonic waveguides.
Summary: A poly(aspartic acid)‐block‐polylactide (PAsp‐block‐PLA) diblock copolymer was synthesized through the polymerization of β‐benzyl‐L ‐aspartate‐N‐carboxyanhydride [Asp(OBzl)‐NCA] with amino‐terminating polylactide (NH2‐PLA) as a macroinitiator. The chain length of the PAsp segment could be easily controlled by changing the monomer/initiator ratio. Dynamic light scattering measurements of PAsp‐block‐PLA aqueous solutions revealed the formation of polymeric micelles. Changes in the micelles as a function of pH were investigated.
The structure and formation of micelles of the poly(aspartic acid)‐block‐polylactide (PAsp‐block‐PLA) diblock copolymers synthesized here. 相似文献
Well‐defined ABC triblock copolymers based on two hydrophilic blocks, A and C, and a hydrophobic block B are synthesized and their self‐assembly behavior is investigated. Interestingly, at the same solvent, concentration, pH, and temperature, different shape micelles are observed, spherical and worm‐like micelles, depending on the preparation method. Specifically, spherical micelles are observed with bulk rehydration while both spherical and worm‐like micelles are observed with film rehydration.
Complementary nucleobase‐functionalized polymeric micelles, a combination of adenine‐thymine (A‐U) base pairs and a blend of hydrophilic–hydrophobic polymer pairs, can be used to construct 3D supramolecular polymer networks; these micelles exhibit excellent self‐assembly ability in aqueous solution, rapid pH‐responsiveness, high drug loading capacity, and triggerable drug release. In this study, a multi‐uracil functionalized poly(ε‐caprolactone) (U‐PCL) and adenine end‐capped difunctional oligomeric poly(ethylene glycol) (BA‐PEG) are successfully developed and show high affinity and specific recognition in solution owing to dynamically reversible A‐U‐induced formation of physical cross‐links. The U‐PCL/BA‐PEG blend system produces supramolecular micelles that can be readily adjusted to provide the desired critical micellization concentration, particle size, and stability. Importantly, in vitro release studies show that doxorubicin (DOX)‐loaded micelles exhibit excellent DOX‐encapsulated stability under physiological conditions. When the pH value of the solution is reduced from 7.4 to 5.0, DOX‐loaded micelles can be rapidly triggered to release encapsulated DOX, suggesting these polymeric micelles represent promising candidate pH‐responsive nanocarriers for controlled‐release drug delivery and pharmaceutical applications.
Redox‐responsive micelles with cores crosslinked via click chemistry are developed to improve the stability of polymer micelles. Amphiphilic block copolymer mPEG‐b‐P(DTC‐ADTC) with pendant azido groups on the hydrophobic chains is synthesized by the ring‐opening polymerization of 2,2‐bis(azidomethyl)trimethylene carbonate (ADTC) and 2,2‐dimethyltrimethylene carbonate (DTC) with monomethoxy poly(ethylene glycol) (mPEG) as an initiator. mPEG‐b‐P(DTC‐ADTC) self‐assemble to form the micelles in aqueous solution and the cores of the micelles are crosslinked via click chemistry to afford redox‐responsive core‐crosslinked micelles. Core‐crosslinking enhances the stability of the micelles in aqueous solution and improve the drug‐loading property. The redox‐responsive core‐crosslinked micelles can be reduced by the addition of reducing agents such as dithiothreitol (DTT), and thus release the loaded drug quickly in the presence of DTT.