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The growing demands of supramolecular hyperbranched polymers integrating noncovalent interaction and unique topological structure merits had received considerable interest in the fabrication of novel materials for advanced applications. Herein, we prepared A2B6-type POSS-containing supramolecular hyperbranched polymers with multiple morphologies including lamellar-like, branched, hollow, core-shell and porous spherical structures through regulating self-assembling monomer concentrations and solvent polarities. The incorporation of appropriate emulative guest molecules would further trigger morphological transformations (such as vesicles and spherical micelles) by synergistic effects of unique POSS aggregation ability, supramolecular complexations and hydrophilic-hydrophobic interactions. Thus, this facile and universal strategy may enable a modular nanofabrication of supramolecular hyperbranched polymers with diversiform topological structure and sophisticated multifunctionality for their potential applications.

Advances in nanotechnology depend upon expanding the ability to create biologically inspired complex materials with well-defined multidimensional structures. Fabrication of hybrid hierarchical stru...

Hydrogels are peculiarly attractive electrolyte materials for constructing flexible and secure all-solid-state supercapacitors due to their mechanical flexibility, ionic conductivity and noninflammability. However, upon severe mechanical stresses, hydrogel electrolyte-based supercapacitors will undergo irreversible structural damage, which results in dramatically fluctuant energy output. Additionally, invalid mechanical flexibility and serious capacitance degradation at subzero temperature are also urgent issues to be addressed. Herein, a mechanically reliable, exceptional-performance and anti-freezing all-solid-state supercapacitor is constructed from a highly ionic conductive double-network (DN) hydrogel electrolyte, intrinsically powerful Ti3C2Tx MXene film electrode and carbon nanotube film current collector. The DN hydrogel possesses impressive ionic conductivities of 4.8 and 3.6 S m−1 at room temperature and −20 °C, respectively, together with an effective energy-dissipation mechanism and freezing tolerance (

The synergistic effects of the combination of hyperthermia and chemotherapy have implicated the critical role of hyperthermia temperatures in clinical practice. Temperature sensitive polymers, whic...

Conductive hydrogels have attracted intensive attention for versatile functions in flexible electronics because of their unique combination of mechanical flexibility and conductivity. However, hydrogels containing plenty of water inevitably freeze at subzero temperature, leading to invalid electronics with failed mechanical advantages and negligible conductivity. Moreover, the inferior elasticity and fatigue resistance of hydrogels result in unstable sensing performance and poor reusability of hydrogel-based electronics. Herein, a freezing-tolerant, high-sensitive, durable strain and pressure sensor was constructed from an ionic conductive chitosan-poly(acrylamide-co-acrylic acid) double-network [CS-P(AM-co-AA) DN] hydrogel with dual-dynamic cross-links (chitosan physical network and ionic coordination [CO2LFeIII]), which was feasibly fabricated by soaking the CS-P(AM-co-AA) composite hydrogel in FeCl3 solution. The ions immobilized in dynamic cross-links exerted crucial effects on improving mechanics [prominent tensile performance, supercompressibility, extraordinary elasticity, fast self-recovery capacity, and remarkable fatigue resistance (1000 cycles)]; meanwhile, the free ions in the hydrogel rendered the hydrogel excellent conductivity and strong freezing tolerance concurrently. The sensor assembled from the DN hydrogel exhibited cycling stability and good durability in detecting pressure, various deformations (elongation, compression, and bend), and human motions even at a low temperature (-20 °C). Notably, the sensitivity on detecting strain and pressure at both room and subzero temperature was superior than most of the reported organohydrogel and hydrogel sensors. Thus, we believe that this work will provide a platform for construction and application of high-sensitive strain and pressure hydrogel sensors with cycling stability and good durability in a wide temperature range.

A general approach to controlled formation of microgels/nanogels is developed for producing hydrogel particles with customizable structures and properties, especially for fabricating multilayered hydrogel particles with flexibly designable structures and properties of each layer. An inverse emulsion technique is adopted to obtain micro- or nanodroplets of a disulfide-linked core/shell hyperbranched polymer. Then pH of the droplets is manipulated to trigger and control in situ core/shell separation of the polymer, dissociation of the shells, and cross-linking of the cores, in the confined space at micro/nanoscales. Loose and compact microgels/nanogels with diverse properties like particle size and swelling capacity are yielded via adjusting the gelation time. Multilayered hydrogel particles with each tailor-made layer are further prepared using the controlled in situ gelation method in association with a seed emulsion technique.

Conductive hydrogels are capturing intensive attention for versatile applications in flexible wearable devices on account of their unique combination of softness, stretchability, conductivity and biocompatibility. However, most of the hydrogel sensors can only serve as single-type sensors to detect strain or pressure, accompanied by a limited detection range. Moreover, the poor anti-freezing performance is also a serious problem to be addressed for their practical applications. Herein, a multi-model, large range and anti-freezing hydrogel sensor was constructed from a high-mechanical and ionic conductive multi-crosslinked poly(vinyl alcohol) (M-PVA) hydrogel, which was prepared via incorporating chain entanglement interaction and complexation between Fe3+ ions and hydroxyl groups into the microcrystalline network through immersion treatment in Fe2(SO4)3 solution. The three reversible and reconstructable crosslinks within the M-PVA hydrogel worked in tandem to achieve ultra-stretchability (1120%), supercompressibility (98%), high toughness, fast self-recoverability and excellent fatigue resistance. Meanwhile, the introduction of Fe3+ and SO42- ions endowed the M-PVA hydrogel with good ionic conductivity and remarkable anti-freezing properties (-50 °C), which benefited the M-PVA hydrogel to act as a freezing-tolerant dressing. The assembled multi-model hydrogel sensor can sensitively and stably detect large range elongation (∼900%), compression (∼70%), bend and pressure (up to 4.60 MPa) concurrently, as well as various human activities including speaking, finger bending and treading behavior. Notably, the hydrogel sensor was capable of maintaining excellent mechanical flexibility and sensitive sensing capacity at low temperature. The M-PVA hydrogel is a promising flexible sensing material for versatile applications in ionic skin, motion recognition and intelligent wearable devices.

Unstable hydrogel-substrate interfaces and defunctionalization at low temperature severely restrict versatile applications of hydrogel-based systems. Herein, various chitosan-polyacrylamide double-network (CS-PAM DN) ionic hydrogels were chemically linked with diverse substrates to construct robust and anti-freezing hydrogel-substrate combination, wherein the destructible CS physical network rendered effective energy dissipation mechanism to significantly enhanced the cohesion of hydrogels and the covalent linkage between PAM network with substrate surface strongly improved the interfacial adhesion. The synergistic effects enabled the CS-PAM DN hydrogels to be tightly bonded on diverse metals and inorganics. Impressively, the hydrogel-substrate combinations were freezing tolerant to well-maintain high interfacial toughness at low temperature. Notably, due to the high toughness and conductivity of hydrogel-metal interface, the hydrogel-metal combination can be utilized as a multi-model flexible sensor to detect strain and pressure within broad temperature range. This work may provide a platform for construction and emerging application of robust, anti-freezing and stable-performance hydrogel-based systems.

A single molecule with multicolour luminescence, especially white emission, is crucial for developing luminescent materials, but it is arduous to be obtained. Herein, we proposed a facile method to fabricate an intriguing single molecule by uniting aggregation-induced emission (AIE) and stimuli-responsive aggregation-caused quenching (ACQ) fluorophores for continuous adjustment of multicolor luminescence. Such a method overcame the challenge and readily achieved a broad, continuous and distinguishable multicolour fluorescence by dual regulation (pH and water fraction) only. By simply tuning pH and water fraction, AIE, ACQ and FRET (fluorescence resonance energy transfer) effects were synergistically regulated, which enabled us to continuously produce over six luminescent colours including orange-red, orange, white, blue, cyan and green. Significantly, the quantum yield of white-light emission with Commission International de L’Eclairage (CIE) coordinates of (0.31, 0.29) could reach up to 12.2%. Furthermore, this unimolecular entity could be applied for multicolour gels and multichannel cell imaging with preferable stability, flexibility and versatility. Particularly, the innovative design concept of synergistically uniting AIE and a responsive ACQ chromophore paves a new way for multifunctional materials in colour-on-demand fields.

An ideal tissue engineering scaffold should imitate physical and biochemical cues of natural extracellular matrix and have interconnected porous structures with high porosity to provide adequate space for cell seeding, growth and proliferation, as well as nutrient delivery and metabolized product elimination. In this study, we examined the feasibility of fabricating microtubule-orientated poly(lactide-co-glycolide) (PLGA) scaffolds with interconnected pores (denoted as MOIP-PLGA) by an improved thermal-induced phase separation technique. We successfully constructed MOIP-PLGA using 1,4-dioxane as the first solvent and benzene or water with lower freezing point as the second solvent. Especially, when water was used, the MOIP-PLGA had higher porosity and it could guide rabbit aortic smooth muscle cells (SMCs) to better grow along the microtubule direction of the scaffold. Comparing with microtubule-orientated scaffold without interconnected pores (denoted as MONIP-PLGA), the proliferation and viability of SMCs cultured on MOIP-PLGA were higher. Moreover, basic fibroblast growth factor could be effectively bound on MOIP-PLGA by a plasma treatment technique and the growth factor could be slowly released in vitro, maintaining bioactivity.

Dendrimers, as a type of artificial polymers with unique structural features, have been extensively explored for their applications in biomedical fields, especially in drug delivery. However, one important concern about the most commonly used dendrimers exists - the nondegradability, which may cause side effects induced by the accumulation of synthetic polymers in cells or tissues. Therefore, biodegradable dendrimers incorporating biodegradability with merits of dendrimers such as well-defined architectures, copious internal cavities and surface functionalities, are much more promising for developing novel nontoxic drug carriers. Herein, we review the recent advances in design and synthesis of biodegradable dendrimers, as well as their applications in fabricating drug delivery systems, with the aim to provide researchers in the related fields a good understanding of biodegradable dendrimers for drug delivery.

We present a highly adaptable design platform for multi-responsive, multilayered composite nanoparticles (MC-NPs) with fine-tunable functional layers. A flexible disulfide-linked nanogel template is obtained by a controlled in-situ gelation method, enabling a high degree of control over each successive layer. From this template, we optimize “smart” biomaterials with biofunctional surfaces, tunable drug release kinetics, and magnetic or pH-responsive functionality, fabricated into MC-NPs for targeted drug release and periosteum-mimetic structures for controlled rhBMP-2 release towards bone tissue formation in-vivo. Such a versatile platform for the design of MC-NPs is a powerful tool that shows considerable therapeutic potential in clinical fields such as oncology and orthopedics., Graphical abstract Image 1, Highlights • A highly adaptable design platform for multi-responsive, multilayered composite nanoparticles. • A flexible disulfide-linked nanogel template is obtained by a controlled in-situ gelation method. • Sequential assembly of multilayered NPs with a nanogel template, porous silica shell, pH-responsive PAA layer, and hydroxyapatite coating. • The ability to finely tune the structure and function of each layer.

The aim to develop stimuli-responsive supramolecular hyperbranched polymers with tunable morphology transitions in solutions has theoretical and practical significance in wide applications. By a combination of a 1 → 7 branching strategy and supramolecular polymerization, here we demonstrate a simple approach to prepare well-defined POSS-embedded stimuli-responsive supramolecular hyperbranched polymers (POSS-SSHPs) with monomer concentration-dependences, pH- and light-triggered disassembly behaviors and solvent polarity-dependent morphological transitions. Further addition of an appropriate amount of competitive guests in selective solvents can achieve other well-organized morphology transitions by the multiple supramolecular driving forces of host–guest inclusion complexations, hydrophilic–hydrophobic interactions and unique POSS aggregation behaviors. This work may provide a universal strategy to construct novel supramolecular polymers with tailored architectures, desired functionalities and potential biomedical applications.

The influence of polymer topology on the nanostructure of amphiphilic copolymer assemblies has been less studied. In this contribution, we regulated the topology of the solvophobic block of poly(N,N-dimethylamino ethyl methacrylate)-b-poly(benzyl methacrylate-co-2-perfluorooctyl ethyl methacrylate) [PDMA-b-P(BzMA-co-FMA)] by reversible addition–fragmentation chain transfer (RAFT) dispersion copolymerization of BzMA and FMA at varying feed ratios. The influence of the variation in the polymer topology on the nanostructure of the corresponding assemblies was evaluated. With the increment of the FMA wt% within the solvophobic block, the size of the PDMA-b-P(BzMA-co-FMA) vesicles increases accordingly. Besides, for PDMA-b-P(BzMA-co-FMA) copolymers whose molecular weights of the solvophobic block range from 88 to 141k, by adjusting the feed ratio of BzMA/FMA, a rich variety of nanostructures were fabricated, including large compound micelles, large compound vesicles, hexagonally packed hollow hoops and nanoporous spheres. Our results indicate that topological engineering of the amphiphilic copolymers via RAFT dispersion copolymerization could be an efficient approach for regulating the nanostructure of polymer assemblies.

The research on the supramolecular hyperbranched polymers (SHPs) that combines the advantages of supramolecular polymer and hyperbranched architecture has attracted considerable interests in many applications. Here we demonstrate a simple approach to prepare POSS-embedded supramolecular hyperbranched polymers (POSS-SHPs) with varied morphology and size by controlling monomer concentration and mixed solvents. The SHPs formations can further transfer into the core-shell structured micelles by addition of competitive guests based on the double supramolecular driving forces.

Hydrogels are a kind of unique cross-linking polymeric materials with three-dimensional networks. Various efforts have been devoted to manipulate the formation of functional hydrogels in situ and enrich the production of hydrogels, microgels and nanogels with improved modulation capacity. However, these methods always fail to tune the gel properties because of the difficulty in achieving the precise control of cross-linking extents once the gel formation is initiated. Therefore, the preparation of tailor-made hydrogels remains a great challenge. Herein, we summarize a controlled cross-linking strategy towards not only fabrication of hydrogels at nano-, micro- and macro-scales, but also achievement of controlled assembly of nanoparticles into multifunctional materials in macroscopic and microscopic scales. The strategy is conducted by controllably activating and terminating the disulfide reshuffling reactions of disulfide-linked core/shell materials with selective core/shell separation using system pH or UV triggers. So it provides a facile approach to producing hydrogels, hydrogel particles and nanoparticle aggregates with tunable structures and properties, opening up the design possibility, flexibility and complexity of hydrogels, microgels/nanogels and nanoparticle aggregates from nanoscopic components to macroscopic objects.

PEG-related adhesives are limited in clinical use because they are easy to swell and cannot support the cell growth. In this study, we produced a series of POSS-modified PEG adhesives with high adhesive strength. Introduction of inorganic hydrophobic POSS units decreased the swelling of the adhesives and enhanced cell adhesion and growth. The in vitro cytotoxicity and in vivo inflammatory response experiments clearly demonstrated that the adhesives were nontoxic and possessed excellent biocompatibility. Compared with the sutured wounds, the adhesive-treated wounds showed an accelerated healing process in wounded skin model of the Bama miniature pig, demonstrating that the POSS-modified PEG adhesive is a promising candidate for wound closure.

Self-assembly schemes provide a simple and tunable approach to creating a myriad of well-defined nanostructures from design of macromolecules in bulk, thin film and solution environments. Here we demonstrated a facile method to construction of tetraphenylethylene nanoparticles (TPE NPs) by decomposition-assembly from pH-responsive and AIE-characteristic vesicles, which were self-assembled by an amphiphilic PEG 750 -POSS-(TPE) 7 polymer in aqueous solutions. The introduction of Schiff base bonds furnished the fluorescent polymersomes with unique pH responsiveness that is stable under physiological conditions but quickly degradable in acidic environments. Interestingly, the luminous vesicles were transformed into spherical TPE NPs in a solution of lower pH on account of the synergetic combination of cleavage rate of the Schiff base bonds and guidance effect of the entangled tadpole-shaped polymeric chains. The AIE feature of TPE molecule was completely retained in the TPE NPs. Compared to the pH-responsive PEG 750 -POSS-(TPE) 7 vesicles, these AIE-active TPE NPs possessed stable morphology and adjustable size by manipulation of the incubation time. These TPE NPs can be quickly internalized into the tumors through endocytosis pathway and retain strong blue luminescence inside the living cells for a long period, presenting the good photostability and biological imaging property. Cytotoxicity assay revealed that TPE NPs were biocompatible and thus can be utilized for long-term live cell imaging and biomedical applications.

Designing versatile functional medical adhesives with injectability, self-healing, and strong adhesion is of great significance to achieve desirable therapeutic effects for promoting wound sealing in healthcare. Herein, a self-healing injectable adhesive is fabricated by physical interaction of polyphenol compound tannic acid (TA) and eight-arm poly(ethylene glycol) end-capped with succinimide glutarate active ester (PEG-SG). The hydrogen bonding induced from the structural unit (-CH2-CH2-O-) of PEG and catechol hydroxyl (-OH) of TA, accompanied by ester exchange between N-hydroxysuccinimide (-NHS) and amino (-NH2) of proteins, contributes to self-healing ability and rapid strong adhesion. Notably, the PEG/TA adhesive can repeatedly adhere to rigid porcine tissues, close the coronary artery under a large incision tension, and bear a heavy load of 2 kg. By exhibiting shear-thinning and anti-swelling properties, the PEG/TA adhesive can be easily applied through single-syringe extrusion onto various wounds. The single-channel toothpaste-like feature of the adhesive ensures its storage hermetically for portable usage. Moreover, in vivo operation and histological H&E staining results indicate that the PEG/TA adhesive greatly accelerates wound healing and tissue regeneration in a rat model. With the specialty of injectability, instant self-healing, and long-lasting strong adhesion to facilitate excellent therapeutic effects, the multifunctional PEG/TA adhesive may provide a new alternative for self-rescue and surgical situations.

The Fabry-Parot etalon can be widely used in the lidar for Doppler wind measurement and aerosol detection. Due to the very wide application of the FP etalon, the standard transmission curve of the F-P is a very important parameter. The general FP etalon measures the transmittance curve by tuning the wavelength of the laser source or tuning the angle of incident light. The FP etalon generally measures the transmittance curve of the etalon by tuning the wavelength of the laser source or use the frequency comb source. Moreover, the tuning of the wavelength and the angle of incident light are nonlinear, and the measurement accuracy is insufficient, and the frequency comb source is very expensive. This paper proposes a new method for testing the transmittance curve of a FP etalon using a similar frequency comb source. The whispering gallery mode is a typical similar frequency comb laser source which has multiple frequency components, but not equal intervals. The spacing of the frequency of the whispering gallery mode is not equal, but the spacing of the frequency can be determined. So, the transmittance curve of the FP etalon can be measured at one time. And the frequency interval and spectral range are tunable easily. This new method greatly reduces the cost of measuring transmission curve, improve measurement accuracy and effectiveness and has great theoretical and practical value.

Hydrogels are required to have high mechanical properties, biocompatibility, and an easy fabrication process for biomedical applications. Double-network hydrogels, although strong, are limited because of the complicated preparation steps and toxic materials involved. In this study, we report a simple method to prepare tough, in situ forming polyethylene glycol (PEG)-agarose double-network (PEG-agarose DN) hydrogels with good biocompatibility. The hydrogels display excellent mechanical strength. Because of the easily in situ forming method, the resulting hydrogels can be molded into any form as needed. In vitro and in vivo experiments illustrate that the hydrogels exhibit satisfactory biocompatibility, and cells can attach and spread on the hydrogels. Furthermore, the residual amino groups in the network can also be functionalized for various biomedical applications in tissue engineering and cell research.

In recent years, hydroxyapatite (HAp) and β-tricalcium phosphate (TCP) were extensively used to prepare composite scaffolds for bone repair. However, due to a lack of systematical evaluation of HAp and TCP composite scaffolds for bone repair, their distinctions on bone regeneration in vivo have not been clearly clarified to date. In this study, we constructed HAp and TCP composite poly(lactic-co-glycolic acid) (PLGA) scaffolds with the same contents of HAp and TCP and similar structures and porosities, and systematically investigated their performance in the repair of rabbits' calvarial bone defects. The HAp/PLGA scaffold possessed stronger mechanical property and higher cell proliferation than the TCP/PLGA scaffold, endowing it with better performance of bone regeneration at an early stage. Since TCP could greatly neutralize degraded acidic products and be slowly absorbed in vivo to release occupied room for new bone growth compared to HAp, the TCP/PLGA scaffold yielded more intact new bone for long-term repair of the defects. Our results clearly demonstrate that TCP is a superior bioceramic for bone tissue engineering, showing promise for the perfect repair of bone defects via tissue engineering.

A series of telechelic supramolecular amphiphiles [POSS–Azo8@(β-CD–PDMAEMA)1→8] was accomplished by orthogonally coupling the multiarm host polymer β-cyclodextrin–poly(dimethylaminoethyl methacrylate) (β-CD–PDMAEMA) with an octatelechelic guest molecule azobenzene modified-polyhedral oligomeric silsesquioxanes (POSS–Azo8) under different host–guest ratios. These telechelic supramolecular amphiphiles possess a rigid core and flexible corona. Increasing the multiarm host polymer coupled onto the rigid POSS core made the molecular architecture tend to be symmetrical and spherical. POSS–Azo8@[β-CD–PDMAEMA]1→8 could self-assemble into diverse morphologies evolving from spherical micelles, wormlike micelles, and branched aggregates to bowl-shaped vesicles. Distinct from the traditional linear amphiphilic polymers, we discovered that the self-assembly of POSS–Azo8@[β-CD–PDMAEMA]1→8 was dominantly regulated by their molecular architectures instead of hydrophilicity, which has also been verified using computer sim...

The small-angle neutron scattering (SANS) technique has been used to investigate the structure of dendrimers based on polyhedral oligomeric silsesquioxane (POSS) in solution. Three generations and two distinct terminal groups (either vinyl or polyethylene glycol (PEG) terminal groups) as well as four concentrations for each dendrimer have been measured in deuterated tetrahydrofuran. Two main scattering regimes, one with a length scale of nm and the other with a length scale of sub-micron, are found to contribute to the SANS signals. In order to fit the SANS data, a new modified two correlation lengths model has been developed. Fit parameters include scale factors, correlation lengths, Porod exponents and “particle” elongation parameters. Our fit results show that the local structure does not correspond to single dendrimer molecules, but rather to POSS-rich domains surrounded by POSS-poor domains. The large-scale structure represents the overall morphology of multi-dendrimer aggregates. The flexible PEG outer links help to enhance the stability of inorganic POSS cages, and allow the hybrid polymers to adjust their conformation in order to respond to their surroundings. With increasing concentration, the local structure becomes more compact as evidenced by the decrease of correlation length and concurrent increase of the Porod exponent. The deformation of local structure during the compaction process is also observed. The structure becomes elongated at intermediate concentrations whereas it tends to be more globular at low and high concentrations.

Soak n' Boost: A universal strategy to manufacture hybrid double-network hydrogels with eminent mechanical properties is developed by postformation of the chitosan microcrystalline and chain-entanglement physical networks via simple treatment of the chitosan composite hydrogels using alkaline and saline solutions. The strategy may open an avenue to fabricate multifarious double-network hydrogels for promising applications in antifouling materials, drug delivery, and tissue engineering.

Medical sealant devices for in vivo hemostasis are far from satisfactory in the aged society. A major challenge is effective integration of quick hemorrhage control of the increased anticoagulated patients, high safety, and facile accessibility. Here, a well-defined ammonolysis-based Tetra-PEG hydrogel sealant is developed with rapid gelation speed, strong tissue adhesion, and high mechanical strength. Introduction of cyclized succinyl ester groups into a hydrogel matrix endows the sealant with fast degradable and controllably dissolvable properties. The hydrogel possesses outstanding hemostatic capabilities even under the anticoagulated conditions while displaying excellent biocompatibility and feasibility. These results reveal that the optimized hydrogel may be a facile, effective, and safe sealant for hemorrhage control in vivo.

As the non-spherical particles could be distinguished from spherical particles easily from polarization lidar measurement, polarization lidar was widely employed in the atmospheric measurements. However, it is very difficult to retrial the particle properties quantitatively from depolarization measurement due to the complex vector scattering model and the calibration of depolarization measurement. In this paper, a method for depolarization calibration of polarization lidar was introduced, and the offset angle of the half-wave plate and gain ratio could be determined exactly by using fitting method. The simulation and lidar measurements indicate that the polarization lidar could be calibrated well by using this method.

Controlled porous structures, adjustable surface properties and good mechanical properties are essential for hydrogels in promoting cell adhesion and growth. In this work, we developed four armed poly(ethylene glycol) (4-arm-PEG) hydrogels crosslinked by poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs). Branched polyethyleneimine (b-PEI) was employed for aminolysis of PLGA to engineer 300, 530 and 1000 nm NPs with a nitrogen contents of 11.7%, 9.4% and 9.7%. Hybrid hydrogels were formed by crosslinking amino-packed NPs with polymeric chains of 4-arm-PEG-NHS. By manipulating the NP and PEG contents as well as the NP sizes, the pore sizes could be tailored from 10–20 μm to 20–40 μm and 100–200 μm, and the maximal compressive strength could be optimized to 0.37 MPa. Cytotoxicity trials indicated the hydrogels were almost non-toxic and biocompatible. Cell adhesion evaluation testified higher amino contents and a smaller proportion of PEG led to more cell attachment. These results demonstrated that this kind of hybrid hydrogel may be a suitable candidate for further biomedical applications in tissue engineering.

An ideal vascular tissue engineering scaffold should imitate physical and biochemical cues in native vessels for guiding cell growth, differentiation and tissue formation. The tunica media provides a key structure and function support for native vessels. In this study, a film-like MNP-TGF/bFGF-PLGA scaffold that simulated physical and biochemical cues of tunica media in native vessels was fabricated by soft lithography combined with solution casting and phase separation technique. The scaffold had dual surface topographies of parallel arranged microgrooves and nanofiber structures, and interconnected pores to be able to deliver nutrient and eliminate metabolized products. The TGF-β1 and bFGF immobilized on the scaffold by silica nanoparticle binding and plasma treatment technique could maintain continuous release for 10 and 7 days, respectively. The synergy effect of the dual surface topography and released growth factors endowed the MNP-TGF/bFGF-PLGA scaffold with good capacity on regulating vascular smooth muscle cell (vSMC) phenotype. Importantly, the scaffold possessed good mechanical properties and could easily be rolled into a multilayer cylindrical tube as a promising biomimic vascular tissue engineering scaffold.

Herein, we report a feasible method to prepare a tadpole-shaped PEG-POSS-(Azo)7 polymer. The polymer self-assembled into a large vesicle in aqueous solution, undergoing reversible smooth-curling transformation responsive to UV and dark conditions. Incorporating POSS units into the azopolymer furnished quick trans–cis isomerization along a cubic orientation. The orientational isomerization formed some pores on the vesicular membrane and endowed the highly sensitive photoresponsive property. Encapsulation of various fluorescent dyes affected the hydrophilic/hydrophobic ratio of self-assemblies, causing their morphological transition from vesicles to micelles. Response to UV irradiation, the quick trans–cis isomerization resulted in rapid release of the encapsulated dyes. The intriguing photoresponsive property renders this kind of tadpole-shaped POSS hybrid azopolymer a potential for application in controlled release of drug.

Well-designed agents for enhanced multimodal imaging have attracted great interests in recent years. In this work, we adopted a premix membrane emulsification (PME) method to prepare uniform PEGylated poly(lactic-co-glycolic acid) (PLGA) microcapsules (MCs) with superparamagnetic Fe3O4 nanoparticles (NPs) embedded in the shell (Fe3O4@PEG-PLGA MCs) for ultrasound (US)/magnetic resonance (MR) bimodal imaging. Compared to Fe3O4@PLGA MCs without PEGylation, Fe3O4@PEG-PLGA MCs could more stably and homogeneously disperse in physiological solutions. In vitro and in vivo trials demonstrated that Fe3O4@PEG-PLGA MCs (∼3.7 μm) with very narrow size distribution (PDI=0.03) could function as efficient dual-modality contrast agents to simultaneously enhance US and MR imaging performance greatly. In vitro cell toxicity and careful histological examinations illustrated no appreciable cytotoxicity and embolism of Fe3O4@PEG-PLGA MCs to mice even at high dose. The uniform composite MCs developed here can act as clinical bimodal contrast agents to improve hybrid US/MR imaging contrast, which is promising for accurate diagnosis and real-time monitoring of difficult and complicated diseases.

It was recently reported that ethanolamine-functionalized poly(glycidyl methacrylate) (PGEA) possesses great potential applications in gene therapy due to its good biocompatibility and high transfection efficiency. Importing responsivity into PGEA vectors would further improve their performances. Herein, a series of responsive star-shaped vectors, acetaled β-cyclodextrin-PGEAs (A-CD-PGEAs) consisting of a β-CD core and five PGEA arms linked by acid-labile acetal groups, were proposed and characterized as therapeutic pDNA vectors. The A-CD-PGEAs owned abundant hydroxyl groups to shield extra positive charges of A-CD-PGEAs/pDNA complexes, and the star structure could decrease charge density. The incorporation of acetal linkers endowed A-CD-PGEAs with pH responsivity and degradation. In weakly acidic endosome, the broken acetal linkers resulted in decomposition of A-CD-PGEAs and morphological transformation of A-CD-PGEAs/pDNA complexes, lowering cytotoxicity and accelerating release of pDNA. In comparison with control CD-PGEAs without acetal linkers, A-CD-PGEAs exhibited significantly better transfection performances.

A high-spectral-resolution lidar (HSRL) can measure vertical profiles of the aerosol backscatter ratio and the aerosol extinction coefficient simultaneously. Fabry-Perot (F-P) interferometer used as a spectrum filter can provide fine frequency resolution with an important impact on HSRL retrieval accuracy. However, in practical applications, the spectral characteristics of the interferometer are affected by many factors. In this article, the impact of several factors on F-P interferometer spectral properties, such as the temperature change, the beam divergence angle, the absorption loss, surface defects and non-parallelism of the interferometer, were analyzed in depth. The performances of F-P interference spectrum filters are modeled and simulated by analyzing the characteristics of lidar echo, respectively using Gaussian model and Bruneau model. Finally, designed the sandwich structure of F-P etalon encapsulation, and the finite element method is used for thermal analysis.

Simulation of retrieving bimodal log-normal aerosol size distribution is accomplished using the algorithm of nonlinear optimal estimation with the aerosol optical parameters combined with three aerosol backscattering coefficients in 355nm, 532nm, 1064nm wavelength (3β) and two extinction coefficients in 355nm, 532nm wavelength (2α). The results show that the parameters characterized the bimodal log-normal function can be successfully retrieved using this algorithm of high accuracy and stability. Given the ±10% uncertainty of the prior value the retrieving results error of the total number of particles and the effective radius are 9.4%, 19% and 9.5%, 22.1% respectively in Bimodal 1 and Bimodal 2. And the geometrical standard deviation brings greater error.

Here we demonstrate a simple and straightforward approach to prepare POSS-embedded hyperbranched (HB-POSS) polymers with customized molecular weights and sizes just by controlling the polymerization time. The polymers can be further used for building amphiphilic polymers, presenting morphological transition from micelle to vesicle in aqueous solution.

Hybrid ionically-covalently crosslinked double-network (DN) hydrogels are attracting increasing attention on account of their self-recovery ability and fatigue resistance, but their relative low mechanical strength and tedious performance adjustment severely limit their applications. Herein, a new strategy to concurrently fabricate hybrid ionic-covalent DN hydrogels and modulate their structures and mechanics is reported, in which an in situ formed chitosan ionic network is incorporated by post-crosslinking the chitosan-based composite hydrogel using multivalent anions solutions. The obtained hybrid DN hydrogels exhibit predominant mechanical properties including superior elastic modulus, high tensile strength, and ultrahigh fracture energy because of the more efficient energy dissipation of rigid short-chain chitosan network. Notably, the swollen hydrogels still remain mechanically strong and tough even after immersion in water for 24 h. More significantly, simply changing the post-crosslinking time can vary the compactness and rigidity of the chitosan network in situ, achieving flexible and efficient modulation of the structures and mechanics of the hybrid DN hydrogels. This study opens up a new horizon in the preparation and regulation of DN hydrogels for promising applications in tissue scaffolds, actuators, and wearable devices.

Microcapsule formulations have been widely developed and used in agriculture to improve pesticide utilization and reduce environmental pollution. However, commercial formulations of chlorantraniliprole (CAP) are only traditional formulations due to poor solubility of CAP in organic solvents. Here, adopting a solid in oil in water (S/O/W) double-emulsion method combined with premix membrane emulsion, we successfully constructed CAP microcapsule formulations with a high loading content. The microcapsule formulations with good light and thermal stability showed a significantly sustained release for a long period, which could be optimally regulated by tuning the surface porosity and size of the porous microcapsules. Bioassay studies showed that control efficacy of the porous microcapsule formulations against Plutella xylostella was superior to that of the commercial formulation. These results demonstrated that such a porous microcapsule delivery system should have great potential for further exploration as a commercial CAP formulation.

Though many responsive polymers have been prepared, none of them can both self-immolate and self-cross-link via responding to the changes of the environment. Here, we introduce a new responsive hyperbranched polymer, which not only can self-immolate but also can self-cross-link via responding to the external stimuli. Moreover, the obtained polymer can form a bioreducible nanogel in its aqueous solution simply via heating, and the formed nanogel can self-immolate via UV irradiation.

The compound of hydroxyapatite-poly(lactide-co-glycolide) (HA-PLGA) was prepared by ionic bond between HA and PLGA. HA-PLGA was more stable than the simple physical blend of hydroxyapatite and poly(lactide-co-glycolide) (HA/PLGA). The surface of HA-PLGA microsphere fabricated by an emulsion–solvent evaporation method was rougher than that of HA/PLGA microspheres. Moreover, surface HA content of HA-PLGA microspheres was more than that of HA/PLGA microspheres. In vitro mouse OCT-1 osteoblast-like cell culture results showed that the HA-PLGA microspheres clearly promoted osteoblast attachment, proliferation and alkaline phosphatase activity. It was considered that surface rich HA component and rough surface of HA-PLGA microsphere enhanced cell growth and differentiation. The good cell affinity of the HA-PLGA microspheres indicated that they could be used as an injectable scaffold for bone tissue engineering.

An ultrasound contrast agent (UCA) plays a key role in ultrasound imaging to precisely diagnose coronary heart disease. Microcapsules composed of inner gas and shell materials are most commonly employed as ultrasound contrast agents. The ultrasonic properties of the microcapsules are significantly dependent on their size and size distribution. Herein, we prepared several uniform sized biodegradable polylactone microcapsules by combining a premix membrane emulsification technique and W/O/W method. We investigated various size-dependent factors to optimize the size and size distribution of the microcapsules. After evaluation for ultrasound imaging, ∼4 μm PLLA (poly(L-lactide)) microcapsules generated more intense ultrasound signals than PLGA7030 or PLGA5050 (poly(lactic-co-glycolic acid), the molar ratio of lactic acid and glycolic acid being 70:30 or 50:50), PEG-b-PLGA7030 (poly(ethylene glycol)-block-poly(lactic-co-glycolic acid)), PLC5050 (poly(L-lactide-co-caprolactone), the molar ratio of lactide and caprolactone being 50:50) and PEG-b-PLLA microcapsules. The signal duration of the PLLA and PEG-PLLA microcapsules could reach ca. 3 and 3.5 min continuously. The ultrasound signal intensity and duration of the signals of PLLA microcapsules were considerably stronger and longer than those of commercially available UCAs, showing that the PLLA microcapsules have a great potential as more efficient UCAs for biomedical imaging.

A series of brush block copolymers (BBCPs) with polynorbornene backbones containing poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene} (PMPCS, which is a rigid chain) and poly(ethylene oxide) (PEO) side chains were synthesized by tandem ring-opening metathesis polymerizations. The weight fractions of PEO in BBCPs are similar, and the degrees of polymerization (DPs) of PEO side chains are the same while the DPs of PMPCS are different. The bulk self-assembling behaviors were studied by small-angle X-ray scattering (SAXS). The neat BBCPs cannot form ordered nanostructures. However, after the doping of lithium salt, the BBCPs self-assemble into lamellar (LAM) structures. When the DPs of the PEO and PMPCS side chains are similar, the LAM structure is more ordered, which is attributed to the more flat interface between PMPCS and PEO phases. The ionic conductivity (σ) values of the BBCP/lithium salt complex with the most ordered LAM structure at different temperatures were measured. The σ value increases with increasing temperature in the range of 40-200 °C, and the relationship between σ and T fits the Vogel-Tamman-Fulcher (VTF) equation. The σ value at 200 °C is 1.58 × 10

A general approach is proposed to synthesize Janus polymer/inorganic composite nanosheets. Onto the amine-group-terminated side of the Janus inorganic nanosheets, initiators are covalently bonded. By a favorable grafting from initiator-terminated side, responsive polymers, for example PDEAEMA and PNIPAM, are synthesized by controlled polymerization for example ATRP or RAFT polymerization. Stable emulsions are easily formed in the presence of the Janus nanosheets, which can be easily de-emulsified by subtle changing physicochemical parameters, for example temperature and pH.

Inspired by the highly ordered nanostructure of bone, nanodopant composite biomaterials are gaining special attention for their ability to guide bone tissue regeneration through structural and biological cues. However, bone malformation in orthopedic surgery is a lingering issue, partly due to the high surface energy of traditional nanoparticles contributing to aggregation and inhomogeneity. Recently, carboxyl-functionalized synthetic polymers have been shown to mimic the carboxyl-rich surface motifs of non-collagenous proteins in stabilizing hydroxyapatite and directing intrafibrillar mineralization in-vitro. Based on this biomimetic approach, it is herein demonstrated that carboxyl functionalization of poly(lactic-co-glycolic acid) can achieve great material homogeneity in nanocomposites. This ionic colloidal molding method stabilizes hydroxyapatite precursors to confer even nanodopant packing, improving therapeutic outcomes in bone repair by remarkably improving mechanical properties of nanocomposites and optimizing controlled drug release, resulting in better cell in-growth and osteogenic differentiation. Lastly, better controlled biomaterial degradation significantly improved osteointegration, translating to highly regular bone formation with minimal fibrous tissue and increased bone density in rabbit radial defect models. Ionic colloidal molding is a simple yet effective approach of achieving materials homogeneity and modulating crystal nucleation, serving as an excellent biomimetic scaffolding strategy to rebuild natural bone integrity.

Cationic polymer vectors have received increasing attention for gene delivery in biotechnology over the past 2 decades, but few polymer vectors were used in clinical applications due to their low gene transfection efficacy. One of the major reasons is that the conventional cationic polymers can induce the increasing of intracellular reactive oxygen species (ROS) concentration and oxidative stress, which reduces the gene transfection efficacy. Here, we create a novel class of thioether dendron-branched polymer conjugate and self-assemble this conjugate into bioreducible cationic nanomicelles with disulfide bond connecting the thioether core to the cationic shell. The obtained nanomicelles have a unique ROS self-scavenging ability, thereby dramatically improving gene transfection efficacy.

Three types of azobenzene-based telechelic guest polymers, PEG-azo, azo-PEG-azo, and PEG-azo4, were synthesized by a facile method. Subsequently, a series supramolecular amphiphiles with three distinct topological structures (hemitelechelic, ditelechelic, and quadritelechelic) were constructed through coupling with host polymer β-cyclodextrin-poly(l-lactide) (β-CD-PLLA) by combined host-guest complexation. Research on the self-assembly behavior of these amphiphiles demonstrated that the variation in self-assembly was tuned by the synergistic interaction of hydrophilicity and the curvature of the polymer chains, and very importantly, the topological structure of amphiphiles demonstrated effective control of the self-assembly behavior.

In recent years, starch microparticles have gained interest in many fields. However, low production, uncontrollable size, and varying size distribution hinder their practical application. Here, we adopt a premix membrane emulsification (PME) method to prepare starch microcapsules at high production rates. The process conditions were optimized to fabricate uniform microcapsules with controllable sizes and narrow size distribution (PDI < 0.1). Through encapsulating avermectin (Av), a kind of water-insoluble pesticide, into the shell of the microcapsules in situ during the process, we developed a pesticide delivery system that enabled a controlled and consistent release of Av over a period of 2 weeks. Kinetic analysis indicated that the mechanisms of Av release involved non-Fickian and Case-II transport. The diameters (0.70-4.8 mu m) of the microcapsules and Av contents (16-47%) were adjusted to achieve suitable release profiles. The results will lay the foundation for further field experiments. (C) 2015 Elsevier Ltd. All rights reserved.

Recent research has indicated that polydopamine and synthetic eumelanins are optoelectronic biomaterials in which one-dimensional aggregates composed of ordered-stacking oligomers have been proposed as unique organic semiconductors. However, improving the ordered-stacking of oligomers in polydopamine nanostructures is a big challenge. Herein, we first demonstrate how folic acid molecules influence the morphology and nanostructure of polydopamine via tuning the π–π interactions of oligomers. MALDI-TOF mass spectrometry reveals that porphyrin-like tetramers are characteristic of folic acid–polydopamine (FA–PDA) nanofibers. X-ray diffraction combined with simulation studies indicate that these oligomers favour aggregation into graphite-like ordered nanostructures via strong π–π interactions. High-resolution TEM characterization of carbonized FA–PDA hybrids show that in FA–PDA nanofibers the size of the graphite-like domains is over 100 nm. The addition of folic acid in polydopamine enhances the ordered stacking of oligomers in its nanostructure. Our study steps forward to discover the mystery of the structure–property relationship of FA–PDA hybrids. It paves a way to optimize the properties of PDA through the design and selection of oligomer structures.