Search

A fabrication strategy for multifunctional organohydrogels is proposed, which combines phase-change microinclusions within a double-network (DN) hydrogel under the stabilization of Janus particles. Janus particles possess reactivity and colloidal stability for more robust organohydrogels, while the interstice among Janus particles enhances the mass transfer between the phase interfaces. Moreover, DN hydrogels are achieved through dynamic cross-linking networks, endowing organohydrogels with injectability and self-healing performance. Phase-change microinclusions are beneficial to the organohydrogels with temperature-responsive mechanical property and temperature-programed shape-memory performance. Organohydrogels can be employed for temperature therapy through the melting-crystallization process of phase-change microinclusions. Simultaneously, the payloads within microinclusions can be released for antibacteria upon melting the encapsulated wax. The organohydrogels can be served as an ideal dressing with temperature-responsive mechanical property, temperature therapy effectiveness, and temperature-triggered antibacterial ability.

A sensitive detection system based on aptamer-based biosensors for the detection of carcinoembryonic antigen (CEA) by mapping encoding upconversion nanoparticles (UCNPs) was constructed. In this sensor, oligonucleotides with CEA aptamer fragments immobilized on magnetic beads (MBs) were hybridized to complementary DNA modified on UCNPs (cDNA-UCNPs); thus, sandwich-structured probes were formed. In the presence of CEA, due to the stronger interaction between the aptamer and CEA than that of the aptamer and complementary DNA on UCNPs, the cDNA-UCNPs were isolated from the MBs, and the number of isolated UCNPs was directly related to the concentration of CEA. Using an inverted fluorescence microscope, the number of target-dependent UCNPs on a glass slide was counted, enabling the accurate determination of CEA in the solution. The dynamic range for CEA detection in PBS buffer was 0.02-6.0 ng mL

Nanoparticles with an anisotropic morphology and composition are flourishing in various scientific fields. Their morphology has a great impact on their functions, but the precise regulation of their growth and final morphology is still challenging. Here, flask-like Janus particles (FJPs) with different compositions segmented on the inner and outer surfaces were fabricated via a sol-gel process using different silane precursors. The neck length of the flask-like particles can be controllably regulated by employing different silane precursors. The Pt catalyst was selectively loaded in their cavities, and as-formed FJPs@Pt are employed as colloidal motors. Due to the adjustable neck length, the Janus colloidal motors have explicit directionality and tunable speeds (max diffusion coefficient is 18.2 μm

Enriching substrates near catalysts is an effective strategy to improve heterogeneous catalytic performance. The surface of PMMA@PIL-PA patchy nanoparticles is segmented into PMMA and PIL-PA domains. The hydrophobic PMMA domain can enrich water-insoluble substrates, while the hydrophilic PIL-PA one catalyzes the reaction of water-soluble and water-insoluble substrates in close proximity. The special patchy nanoparticles with both a hydrophobic substrate warehouse and catalysis functional divisions can effectively improve the catalytic efficiency. They were employed to catalyze the acetal reaction between water-insoluble benzaldehyde and water-soluble ethylene glycol by phosphotungstic acid (PA). Compared with the homo-nanoparticles, the conversion rate was greatly improved.

The polymer/inorganic composite trilayered Janus mesoporous nanodiscs are synthesized by coassembly of gelable poly(ethylene oxide)-block-poly(3-triethoxysilylpropyl methacrylate)-block-polystyrene (PEO-b-PTEPM-b-PS) and PEO-b-PS via a sol–gel process at an emulsion interface. Bimodal phase separations are responsible for the formation of isolated nanodiscs and mesopores within the discs. The Janus mesoporous nanodiscs are amphiphilic to form superstructures in dispersions. They can serve as a solid surfactant to stabilize emulsions.

Tadpole-like Janus nanotubes with controlled size are fabricated by a sol-gel reaction at the emulsion interface. Pd or Fe3O4 nanoparticles can be selectively captured into their cavities to obtain tadpole-like Janus Pd-nanotubes or tadpole-like Janus Fe3O4-nanotubes. They can be driven directionally by a chemical fuel or near-infrared (NIR) light.

Poly(lactic acid) (PLA), one of the most promising biodegradable polymer products, has achieved wide applications for its relatively good mechanical properties and moderate degradability. Here we report an environment-friendly filler, the organic-inorganic composite Janus nanosheets (PLA/PBS JNs), which can jam at the interface of the PLA/PBS blend with a low threshold as the compatibilizer and can simultaneously toughen the composites and improve the gas barrier performance due to better interfacial interaction and tortuous path effect. With 0.3 wt % of PLA/PBS JNs added, the tensile strength and elongation at break of the PLA/PBS blend can be improved by 37% and 224%, respectively. After a further hot-pressing process, the barrier performance of the PLA/PBS composite membranes can be significantly enhanced since PLA, PLA/PBS JNs, and PBS are arranged in a nearly lamellar structure with oxygen permeability of 0.63 × 10

We report a new jellyfish-like Janus polymeric cage and its synthesis by two-step emulsion interfacial polymerization. The “head” part is generated by the free-radical polymerization of styrene/div...

A zwitterionic polymeric hair-coated stainless steel mesh membrane is fabricated, which demonstrates efficient separation of oil/water mixtures and emulsions. The hairy coating of poly(divinylbenzene-co-vinylbenzene chloride) is generated by precipitation cationic polymerization, and subsequently grafting a zwitterionic polymer layer by atom transfer radical polymerization of sulfobetaine methacrylate. The microstructure of the hairy coating is tunable from an array of individual nanofibers to porous networks by interweaving of the hairs. The long-range attraction of zwitterionic polymers with water renders the coated mesh with excellent superhydrophilic and underwater superoleophobic performance. The coated mesh is highly antifouling to avoid the prehydration in conventional methods. Moreover, the microstructure is demonstrated to be responsible for the high separation efficiency of oil/water emulsion. Therefore, separation of oil/water mixtures and emulsions becomes easier by the coated mesh, which is promising in industrial oil field sewage treatment.

Alcohols are discovered for the first time to tune the morphology of poly(vinyl benzyl chloride)-poly(3-methacryloxypropyltrimethoxysilane) (PVBC-PMPS) composite particles through seeded emulsion polymerization within the alcohol/water mixture. Here, monodispersed linear PVBC particles was synthesized through the dispersion polymerization and employed as the seeds. The as-obtained PVBC-PMPS composite particles could be dramatically tuned from core-shell structures to snowman-like particles, to dumbbell-shaped particles, to inverse snowman-like particles when the ethanol content in reaction mixtures is only adjusted within a narrow range. The morphology of fresh PMPS bulges was observed after removing the linear PVBC seeds with N,N'-dimethyl formamide, and their formation mechanism was studied by monitoring the free radical polymerization and sol-gel process of 3-methacryloxypropyltrimethoxysilane. It has been confirmed that the sol-gel kinetics were the main factor on the particles' morphology. In addition, morphologies of PVBC-PMPS particles were also varied by the MPS feeding amount, types of the co-solvent and pH values of alcohol/water mixtures.

We describe a simple method to prepare magnetic responsive polydivinylbenzene (PDVB) nanofiber composites by precipitated cationic living polymerization in the present of oleic acid capped Fe3O4 nanoparticles (NPs). The Fe3O4 NPs are encapsulated with the PDVB forming dendrites, from which thin nanofibers are grown in the tip-growth mode. The thin nanofibers are interwoven with the thick nanofibers forming robust composite network. The composites are magnetic responsive and highly efficient to gel almost all chemicals. Separation of the gelled chemicals from water becomes easier with a magnet. The performance is promising for magnetic collection of chemical spills.

A bottlebrush-colloid Janus nanoparticle (JNP) with a ball-and-stick structure is reported. A single poly(4-vinyl benzyl chloride) (PVBC) polymer chain was grafted onto the amine-capped Fe3O4@NH2 n...

In this work, we developed a continuous non-aqueous flow Pickering emulsion interface catalysis (FPIC) system for heterogeneous acylation. Poly (1-vinyl-3-ethylimidazolium bromide) (PILs) functionalized silica@PS/PDVB Janus particles (JPs) were synthesized. The catalyst H3PW12O40 (PA) was then immobilized on PIL-modified JPs by anion-exchanging. The PIL grafted on the silica side and the inherent oleophilic phenyl groups on the other side endow the Janus particle with excellent amphipathy for the immiscible ionic liquid (IL) [BMIM]BF4 and toluene. Therefore, emulsification and catalytic capability were realized simultaneously on the PA-PILs-JPs. The FPIC column system for acylation reaction was accomplished by packing the IL-in-oil Pickering emulsion into a column reactor, and exhibited excellent catalytic performance, high stability during the reaction process as well as remarkable recyclability.

Strength is usually compromised with toughness of polymer blends. We report a new way to synchronously strengthen and toughen a typical blend of epoxy resin/nitrile-butadiene rubber (EP/LNBR) with ...

Hairy composite particles with polymer nanoscale hairs are grown by precipitated cationic living polymerization onto a particle surface. Composition and length of the hairs are tuneable. The hair growth is general following the tip-growth mode. By step polymerization of varied monomers, multiple segmental hairs are achieved onto a particle surface. As an example, the PEG-conjugated PVBC-PDVB@Fe3O4 hairy particle is derived. It is highly effective to capture oil from the aqueous surroundings and easily recycled with a magnet.

A Janus silica cage was synthesized by selectively grafting an ionic liquid (IL) and poly-N-isopropylacrylamide (PNIPAM) (lower critical solution temperature (LCST)≈32 °C) onto the exterior and interior sides of the mesoporous SiO2 shell. The paramagnetic core inside the cavity is responsible for magnetic collection. The PW12 O40 3- anion is further conjugated onto the IL side by anion exchange. The Janus cage acts as a thermal-responsive reactor for catalytic oxidization of dibenzothiophene (DBT) in the presence of H2 O2 . The sulfide in the model oil can be completely decomposed at 25 °C, whilst the oxidative products are more dissoluble in water and preferentially captured inside the Janus cage. The Janus cage reactor could be regenerated at high temperature above 32 °C after releasing the products.

We report a method to prepare polymer/inorganic Janus particles by transferring self-assembled membranes of copolymers such as PS- b-PAA at an emulsion interface when the amine-capped particles such as paramagnetic Fe3O4@SiO2 core/shell particles are preferentially adsorbed by specific interactions. While the particles are protected, the exposed side can be further modified to conjugate aldehyde-capped polyethylene oxide (PEO). Both connections become robust by covalent bonds. The hydrophilic PEO and hydrophobic PS chains are distinctly compartmentalized onto the opposite sides of the Fe3O4@SiO2 particles. As a magnetic responsive solid surfactant, the stabilized emulsions can be driven with a magnet for directional movement and coalescence with increasing magnetic strength. This method can be extended to other Janus particles with tunable organic materials and solid particles.

Snowman-like silica@PDVB/PS Janus particles were fabricated via seeded emulsion polymerization and modified with hydrophilic ionic liquid moieties. The Janus particles can readily be further modified by incorporating new functionalities through simple anion exchange. PW12O403– as a catalytically active species for dye degradation was introduced into the Janus particles, and the performance in the catalytic degradation of methyl orange was evaluated.

Triblock Janus particles are prepared by two-step seeded emulsion polymerization against eccentric polymer hollow particles. Two silica bulges are sequentially grown at the eccentric zone transiting from the thick shell to the thin shell. The angle between the two silica bulge axes is tunable within 0–180°, determined by the eccentricity degree of the PS/PDVB hollow seed particles. The two silica bulges and the PS/PDVB domain of the triblock Janus particles can be selectively modified to enrich composition and functionality. As an example, the paramagnetic PS/PEO modified triblock Janus composite particle can serve as a functional solid surfactant to manipulate emulsion droplets with a magnet and deliver desired materials toward the interface.

A superhydrophobic surface was achieved using a monolayer of the perpendicularly oriented epoxy-silica@polydivinylbenzene (PDVB) Janus particles (JPs) on an epoxy resin substrate. The epoxy-silica@PDVB JPs were synthesized from the silica@PDVB/polystyrene (PS) JPs through selective etching of the PDVB/PS belly and the surface modification of the silica part. The modified silica parts can be covalently bonded with the epoxy resin to make the perpendicular orientation spontaneous as well as the coating more robust. The outward PDVB bellies can constitute the micro-/nanoscale hierarchical structures for the superhydrophobic property. The superhydrophobic coating exhibits water repellence and self-cleaning properties. Moreover, the coating exhibits good chemical durability that it can keep the superhydrophobic property after long-time immersion in various aqueous solutions and organic solvents. The coating is still superhydrophobic after water flushing and mechanical wearing, showing the perfect mechanical durability.

When superhydrophobic meshes are used for oil/water separation, high flux and high intrusion pressure are usually compromised. Herein, a high-performance superhydrophobic stainless steel mesh membrane with a hairy-like poly(divinylbenzene) (PDVB) coating is fabricated by precipitated cationic polymerization. The synthesis is facile, which is completed in one step at ambient temperature within a short time, i.e., less than 90 s. The unique hair-like microstructure of PDVB is responsible for the superhydrophobic performance with less blockage for the pores. A higher flux for oil is achieved while keeping a high intrusion pressure. Especially, the ellipsoidal pore texture with two sharp tips can give additional high intrusion pressure. In the case of 2800 mesh, the superhydrophobic mesh displays an unprecedentedly high value of up to 22 kPa while maintaining a high flux of 2.0 × 104 L·m-2·h-1. The high intrusion pressure enables further increment of flux to 4.2 × 104 L·m-2·h-1 under a reduced pressure at a higher loading. The current high-performance superhydrophobic mesh realizes higher efficiency in separating oil/water mixtures, which is promising for practical applications, for example, in industrial extraction.

For double network (DN) hydrogels, their performance can be tuned by adjusting the interaction between their two networks. A novel DN hydrogel toughening approach is proposed by employing Janus nanoparticles (JNs) as crosslinkers to gain a conjoined-network hydrogel. First, a kind of JNs modified by amino groups and quaternary ammonium salt is synthesized, named R

A robust thermo-responsive polymeric Janus cage with a PNIPAM-cPVBC-PEO sandwiched shell is synthesized. The Janus cage provides a general method of thermally triggered separation of oil/water emulsions independent of the type of surfactant and emulsion. It can selectively capture organic compounds at a higher temperature and release them at a lower temperature.

A strategy is proposed to stabilize the polymeric interface by using the irregular Janus nanosheet (JNS). The poly(vinylidene fluoride) (PVDF)/poly(l-lactic acid) (PLLA) at 60/40 (wt/wt) with a bi-continuous structure is selected as the model melt blend, and the PMMA/epoxy JNS is synthesized and used as the compatibilizer. The JNS is preferentially located at the interface. The interfacial coverage by the JNS reaches a saturated state forming the interconnected jamming structure at 0.5 wt% of the JNS. The interface is thus stabilized which is well preserved after annealing at high temperature. After selectively etching PLLA, the robust PVDF porous material is derived with the JNS armored at the pore skeleton surface. The porous material provides a universal scaffold to achieve stable functional materials after filling the pores.

One-dimensional nanomaterials have widely applied in the fields of energy conversion and storage due to their exceptional performance because of the nano-size effect. Herein, we synthesized bamboo-like polymer nanotubes based on cationic polymerization using immiscible initiator nanodroplets that results in a hollow structure. The suspended microelectrode is fabricated to measure the axial thermal conductivity of a single polymer nanotube, which demonstrates that this hollow structure can reduce its effective thermal conductivity. The experimental results show that its effective thermal conductivity is close to 0.03 W m-1 K-1, and decreases to 0.02 W m-1 K-1 with increasing temperature of the heating microelectrode, which may be due to the increasing lattice vibration and inelastic scattering between phonons. Its effective thermal conductivity is smaller than that of air, indicating that the synthetic method is an effective way to fabricate thermal insulating polymer nanotubes by significantly lowering the effective thermal conductivity. Hence, the method offers a new strategy in the fields of thermal insulation and protection.

Polymeric micelles of amphiphilic block copolymers have been studied for decades for their application as a targeting delivery agent of anti-tumor drugs. However, the targeting micelles may cause an immunological response because of the surface distributed ligands. In this work, mixed micelles were developed to improve the specificity of cancer cell uptake under tumor-acidic conditions. This was achieved by the co-assembly of an active targeting amphiphilic polymer, i.e. cyclic (Arg-Gly-Asp-d-Phe-Lys) c(RGDfK) functionalized poly(ethylene oxide)-b-poly(e-caprolactone) (cRGD-PEO-b-PCL), and a pH sensitive drug conjugate, i.e. benzoic-imine linked PEGylated doxorubicin (PEG-DOX). Because the PEG-DOX is cleavable at the extracellular pH of a solid tumor, the characteristics of the mixed micelles turn from "stealthy" to cancer cell-affinitive due to the detachment of PEG from the micelle surface and hence allow the action of the c(RGDfK) in the cRGD-PEO-b-PCL with the cancer cell membrane. Besides, the mixed micelles exhibited the capacity for encapsulating hydrophobic drugs such as paclitaxel to form a combination formulation. Our results indicate that co-assembly is a facile but efficient strategy to coordinate the characteristics of each individual component and thus provide combinatorial functions to the delivery system.

In addition to intravenous injections (i.v.), topical dosing of doxorubicin hydrochloride (DOX) has also been the focus of cancer treatment recently, although it normally requires well-designed drug carriers. In this work, we found that DOX could form fibril-shaped DOX aggregates via self-assembly in phosphate buffer (PB) and then co-assemble with poly(L-glutamic acid) (PGA) at a proper polymer–drug ratio, giving a unique nano-rod-shaped microstructure. The release rate of DOX from the PGA/DOX nano-rods was thus easily controlled at a slower release rate without being encapsulated by any classic carrier. In vitro cell culture demonstrated that the PGA/DOX nano-rods were not favorably taken up by cancer cells, which can be attributed to the negatively charged nature and the non-spherical shape of the aggregates. These features suggest great potential for the PGA/DOX assemblies for a sustained delivery through the intratumoral pathway (i.t.) as a carrier-free formulation. In the mouse model it diminished organ damage at a dose level of 30 mg kg−1via i.t. injections compared to the serious cardiotoxicity and renal toxicity via typical multiple i.v. dosage of free drug solution at 5 mg kg−1. As a result, the PGA/DOX formulation showed efficient anti-tumor activity. The survival rate of tumor bearing mice was significantly increased by over 35% compared to the i.v. injections of DOX solutions. Therefore, PGA/DOX nano-rods may provide a new and safe delivery route of the common anti-tumor drug.

The aim of this study was to investigate the suppression of inflammation and enhancement of osteogenesis using chitosan-coated calcium hydroxide-loaded microcapsules (CS-EC@Ca microcapsules) in vivo. Circular defects were created in the mandibular bones of rabbits and filled with Ca(OH)2 , Bio-oss, or CS-EC@Ca microcapsules, and rabbits without drug implantation served as the controls. Lipopolysaccharides were injected in situ daily in all groups for 7 days. Mandibular bones were investigated at 4 and 12 weeks after surgery using micro-CT, histological observations, and real-time PCR analysis. At the postoperation, there was more substantial nascent bone in the microcapsule and Bio-oss groups than in the control group. The recovery of the rabbits in the Ca(OH)2 group was slower than the control group, as determined using micro-CT and histological staining. Osteocalcin and collagen type I production was not significantly different between the microcapsule and Bio-oss groups (p > 0.05), but the expression levels of the two molecules were significantly increased compared to the control and Ca(OH)2 groups at postoperation (p < 0.05). The mRNA transcript levels of inflammatory factors in the microcapsule group had the most reduced expression of IL-6 and TNF-α (p < 0.05). The microcapsules significantly reduced inflammation and promoted osteogenesis in this rabbit model of inflammatory bone destruction. Our findings indicate that CS-EC@Ca microcapsules hold potential for use in apical periodontitis treatment. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3222-3230, 2018.

Cable-like Au@SiO 2 Janus composite nanorods with PS and PEG grafting on both ends respectively are fabricated by skiving in combination of a post favorable modification. The cable-like Au@SiO 2 composite nanofibers are synthesized in the channel of porous anodic aluminium oxide (AAO) membrane. After skiving, the corresponding composite nanorods are obtained. Following, PEG-SH and PS-SH are conjugated onto the two ends of the nanorods by a selective partial modification, respectively. Length and diameter of the Au@SiO 2 Janus composite nanorods can be tuned controllably. It can be extended to fabricate a variety of different Janus nanorods with different compositions and microstructures.

The amphiphilic monomer 2-hydroxyethyl methacrylate (HEMA) is widely used in dental adhesives as a priming component, especially for dentin bonding. It behaves as a compatibilizer between hydrophilic and hydrophobic components and stabilizes the multicomponent adhesive system. However, there are several drawbacks associated with using HEMA, such as water retention within the adhesive layer, hydrolysis in oral environments, and cytotoxicity. These drawbacks lead to the failure of tooth restoration and represent a heavy medical burden. Thus, it is imperative to find a new compatibilizer to substitute for HEMA. Because of their superior compatibilization capabilities as functional solid surfactants, amphiphilic Janus particles are chosen as candidates for an alternative to HEMA in dental adhesives. Reactive amphiphilic Janus nanoparticles are synthesized by selectively etching and modifying at the interface of a Pickering emulsion. This approach could be extended to the synthesis of a series of other Janus nanoparticles. The Janus nanoparticles were verified to be better for the reduction of the phase separation and stabilization of dentin adhesives than HEMA. It is also demonstrated that these reactive Janus nanoparticles can strongly enhance the dentin bonding interface without cytotoxicity. It is clearly illustrated by this study that Janus nanoparticles may be promising materials to substitute for HEMA in dental adhesives.

A new method is proposed to fabricate high-performance phase change material capsules with high thermal storage capacity and increased thermal conductivity . The capsules are achieved by free radical polymerization against the example paraffin/water emulsions stabilized with Janus particles (JPs). It is key that the highly conductive Ag-contained JP adopt parallel lying at the emulsion interface, which is responsible for increasing the interfacial thermal conductivity. Thermal storage capacity can be retained over 90% with no paraffin leakage, which is stable after many cycles of heating and cooling. The high-performance phase change material capsules are promising in effective thermal management in the form of either powder or slurry.

Janus colloids are functional particles consisting of two surfaces (or internal materials) with distinct physical or chemical properties in the same particle. Owing to their amphiphilic nature, Janus colloids composed of both hydrophilic and hydrophobic faces provide a powerful tool to generate functional surfaces and to manipulate the properties of interfaces. Amphiphilic Janus colloids have shown promising applications as particulate surfactants in oil/water separation, as interfacial compatibilizers in polymer blends, and as assembly blocks in robust coatings with unique wettability. In this Feature Article, we summarize recent advances in engineering interfaces by using Janus colloids.

We report a general method to synthesize polymeric Janus nanosheets (PJS) by sequential RAFT grafting from a template particle surface. Layer number and composition of the PJS are tunable by feeding sequence and type of monomers. The cPNIPAM–PS PJS is flexible and thermal responsive, which can form a scrolled superstructure. A dually responsive cPAA–PNIPAM PJS is derived by hydrolysis of cPtBA–PNIPAM. Accordingly, stability of the emulsion with the cPAA–PNIPAM PJS is triggered by alternation of pH or/and temperature.

A robust light-responsive coating based on Janus composite particles is achieved. First, strawberry-like silica Janus particles are synthesized by the sol-gel process at a patchy emulsion interface. One side of the silica Janus particles possesses nanoscale roughness, and the other side is flat. Then, spiropyran-containing polymer brushes are grafted onto the coarse hemispherical side of the as-synthesized Janus particles, and the other flat side is modified with imidazoline groups. The light-responsive polymer brush-terminated coarse hemispherical sides direct toward the air when the Janus composite particles self-organize into a layer on the surface of epoxy resin substrate. The imidazoline groups react with the epoxy groups in the epoxy resin to form a robust smart coating. The coating can be reversibly triggered between hydrophobic and hydrophilic by UV and visible-light irradiation, which is attributed to the isomerization of spiropyran moieties. When the hydrophobic ring-closed spiropyran form is prominent, HeLa cells can be effectively captured onto the coating. After UV light irradiation, the ring-closed spiropyran form changes to the hydrophilic ring-opened zwitterionic merocyanine form, and then the captured cells are released. This work shows promising potential for engineering advanced smart biointerfaces.

Polymer/metal composite segmental Janus nanoparticles (NPs) are synthesized by sequential growth against poly(4-vinylpyridine) (P4VP) crosslinked cP4VP-PS Janus NPs. A Janus cluster of poly(4-vinylpyridine)-block-polystyrene (P4VP-b-PS) diblock copolymer is self-organized after absorption onto a silica patchy sphere via hydrogen bonding. Selective crosslinking of P4VP leads to the formation of robust cP4VP-PS Janus NPs. Within the cP4VP domain, functional species such as metals are preferentially grown by in situ reduction. Other thiol-capped polymers, for example, thiol-capped poly(N-isopropylacrylamide) (PNIPAM-SH), can be conjugated onto the opposite side to form polymer/metal triple segmental Janus NPs. The hyperthermia effect of Au NP of PNIPAM-Au@cP4VP-PS by near infrared (NIR) irradiation can trigger a fast transition from amphiphilic to hydrophobic of the Janus NPs at low surrounding temperature. De-stabilization of the emulsion is NIR triggered although the system temperature is below LCST (~32℃).

A major shortcoming of contemporary dentin adhesives is their limited durability. Exposed collagen fibrils within the bonding interface are degraded by matrix metalloproteinases (MMPs), resulting in aging of the resin-dentin bond. In this study, chlorhexidine-loaded amorphous calcium phosphate (ACP) nanoparticles were synthesized to induce the mineralization of collagen fibrils. The nanoparticles sustainably released chlorhexidine to inhibit MMPs during mineralization. Three types of ACP nanoparticles were prepared: N-ACP containing no chlorhexidine, C-ACP containing chlorhexidine acetate, and G-ACP containing chlorhexidine gluconate, which had a higher drug-loading than C-ACP. Scanning and transmission electron microscopy indicated that the synthesized nanoparticles had diameters of less than 100 nm. Some had diameters of less than 40 nm, which was smaller than the width of gap zones in the collagen fibrils. Energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and high performance liquid chromatography confirmed the presence of chlorhexidine in the nanoparticles. X-ray diffraction confirmed that the nanoparticles were amorphous. The drug loading was 0.11% for C-ACP and 0.53% for G-ACP. In vitro release profiles indicated that chlorhexidine was released sustainably via first-order kinetics. Released chlorhexidine inhibited the degradation of collagen in human dentine powder, and its effect lasted longer than that of pure chlorhexidine of the same concentration. The ACP could induce the mineralization of self-assembled type I collagen fibrils. The chlorhexidine-loaded ACP nanoparticles sustainably released chlorhexidine and ACP under appropriate conditions. This is useful for inhibiting degradation and inducing the mineralization of dentine collagen fibrils.

Ultrathin Janus nanodiscs with single molecular scale thickness are fabricated by self-organized sol–gel process against a patchy magnetic microsphere. Functional groups onto the patch domains can induce a favourable absorption of an amine. The morphology of Janus nanodiscs is adjusted by controlling the patchy regions on the surface of paramagnetic Fe3O4@SiO2 core/shell microspheres. The as-used patchy C8–(Fe3O4@SiO2)–PhCHO microspheres serving as templates can be easily separated from the as-formed Janus nanodiscs and reused to fabricate other Janus nanodiscs. Functional compositions such as paramagnetic Fe3O4 nanoparticles and polymers with different wettability properties are introduced onto the different regions of Janus nanodiscs to achieve magnetic Janus nanodiscs. They are used as efficient solid surfactants to stabilize emulsion.

We present a review of the very recent advances in the synthesis of block copolymer (BCP) Janus nanomaterials. Although Janus micelles can form by the self-assembly of BCPs in solution, patchy or core–shell structures are usually dominant. Structural transformation of the core–shell structure or disassembly of the patchy structure is further employed to achieve Janus nanomaterials. Disassembly of ABC tri-block terpolymer supramolecular structures is advantageous in tuning much more easily the shapes of the Janus nanomaterials from spherical to cylindrical and sheet/disc-like. Narrow molecular weight distributions and strict processing conditions are required. Emulsion droplet confined self-assembly of BCPs can directly achieve Janus nanomaterials in a sufficiently small droplet and/or at low polymer concentration. A neutral emulsion interface is required using proper surfactants. Alternatively, a general method has been proposed to prepare Janus nanomaterials by guided self-assembly of BCPs within a confined environment by the strong interaction and the selective crosslinking of one block. The aforementioned Janus nanomaterials are in the form of a polymer cluster. Single chain Janus nanomaterials of BCPs can be prepared by intramolecular crosslinking of one block in a very dilute solution. It remains challenging to synthesize single chain Janus nanomaterials at high solid content for example tens of percent. At the end of this review, a perspective on BCP Janus nanomaterials is provided.

In this work, an injectable composite hydrogel was synthesized via a unique way of crosslinking glycol chitosan (GC) with silica nano-particles (SiNP) through non-chemical interactions, and was then applied as a kind of wound dressing. Gelation was achieved through the incorporation of SiNPs with the GC segments in aqueous solution, therefore strictly confining the movement of the solubilized polymer chains. Rheology tests showed that the sol-gel transition and the moduli of the hydrogel were influenced by the composition of the two components, the size of the nano-particles and the conformation of the polymers. Using such a strategy, tissue adhesion properties of GC were well-preserved in the GC/SiNP hydrogel and therefore it gains gluey properties toward biological tissues as demonstrated through the adhesion of two pieces of mouse skin, obtaining a lap-shear stretching force of ca. 90 kPa. This characteristic, together with the injectability, allowed the hydrogel to be administrated directly on the wound site and to fill the wound area. Meanwhile, the hydrogel also works as a carrier of protein and cells. The in situ encapsulation of fibroblasts enabled the promising properties of the GC/SiNP hydrogel to be used for treating full-thickness skin defects in a mouse model, resulting in the favorable growth of hair follicles and microvessels, hence reducing the risk of scar formation.

Efficient control of Tetranychus cinnabarinus (B.) is in challenge worldwide. Herein we report the use of an amphiphilic block copolymer, poly(ethylene oxide)-b-poly(caprolactone) (PEO–PCL), as a micellar carrier to make formulations of ricinine, a water insoluble botanical pesticide, and the tests of their physical properties and moreover the acaricidal activity on Vigna unguiculata (L). Compared to the formulations made from small molecular surfactant, e.g. Tween-80, the polymer formulations showed differentiated spreading property on T. cinnabarinus (B.) and V. unguiculata (L.) leaf surfaces, i.e. having slightly lower contact angle on the mite's integument. This contributes a relatively easy wash-off performance of the polymer formulations from the V. unguiculata (L.) leaf and meanwhile an enhanced protection to the plant in the simulated field trial. Our work thus suggests favorable characteristic of amphiphilic polymer in the future development of insecticides.

A Fe3O4 nanoparticle (NP) based on composite Janus NP with single polymer chain is prepared by termination of the modified Fe3O4 NP with the anionic living polymer chain. The requisite that the polymer chain should be sufficiently large over the NP diameter determines the grafting of single polymer chain. From the opposite side of the NP surface, functional species can be selectively grown for example grafting responsive PNIPAM by ATRP. Besides simple combination of the thermal and magnetic responsive performances of different components, the PS–Fe3O4–PNIPAM composite Janus NP shows additional interactive performance such as NIR-triggered Janus/hydrophobic transition at low surrounding temperature below LCST ∼ 32 °C.

The Fe3O4@SiO2 paramagnetic Janus particles with phenyl groups and amino groups segmented on two different sides were fabricated by the Pickering emulsion method. Then, the poly(ionic liquid)s were...