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Innovative methodologies combined with scavenging reactive oxygen species (ROS), alleviating oxidative stress damage and promoting macrophage polarization to M2 phenotype may be ideal for remodeling implant-infected bone tissue. Herein, a functionalization strategy for doping Tannic acid-d-tyrosine nanoparticles with photothermal profile into the hydrogel coating composed of konjac gum and gelatin on the surface of titanium (Ti) substrate is accurately constructed. The prepared hydrogel coating exhibits excellent properties of eliminating biofilm and killing planktonic bacteria, which is based on increasing susceptibility to bacteria by the photothermal effect, biofilm-dissipation effect of D-tyrosine, as well as the bactericidal effect of tannic acid. In addition, the modified Ti substrate has effectively alleviated proinflammatory responses by scavenging intracellular excessive ROS and guiding macrophages polarization toward M2. More interesting, conditioned medium from macrophage indicates that paracrine is conducive to osteogenic proliferation and differentiation of mesenchymal stem cells. Results from rat model of femur infection in vivo demonstrate that the modified Ti implant significantly eliminates the residual bacteria, relieves inflammation, mediates macrophage polarization, and accelerates osseointegration. Altogether, this study exhibits a new perspective for the development of advanced functional implant with great application potential in bone tissue regeneration and repair., (© 2023 Wiley-VCH GmbH.)

Polysaccharide-based hydrogels are remarkable materials for the biomedical fields because of its excellent biodegradation and biocompatibility. In this work, a novel polysaccharide-based hydrogel was fabricated by in situ crosslinking of starch-based nanoparticles and polyvinylamine. Starch was decorated with cholesterol group and aldehyde groups. TEM and DLS showed that the cholesterol modified oxidation starch (OCS) exhibited a core-shell nanoparticles with mean size of ∼143 nm in aqueous. The hydrogel was then synthesized via Schiff base reaction. Rheological measurements demonstrated the incorporation of cholesterol groups not only reduced the gel time but also improved the storage modulus of the hydrogel compared with the oxide starch crosslinked hydrogel. SEM showed the OCS based hydrogels possess a well-defined porous structure. Furthermore, doxorubicin (DOX) was used as model drug to investigate the control and release properties of OCS hydrogels. This OCS hydrogel would be a promising drug carrier for biomedical applications., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In this study, the blank hydrogels and the niosomal hydrogels loading coenzyme Q10 (CoQ10) were prepared by carbomer (CBM) and scleroglucan (SCL), and their physicochemical properties were characterized in terms of rheological and texture measurement, FTIR, SEM, DSC, and DLS. First, the blank hydrogels CBM‐SCL‐Gel were prepared. With the increase of SCL concentration, the viscosity and modulus increased, displaying better shear thinning behavior of pseudoplastic fluid. A dense network structure was formed in CBM‐SCL‐Gel, especially for CBM/SCL at 5/4 and 5/5, due to hydrogen bonding between CBM and SCL. The swelling behaviors of the composite gels conformed to pseudo‐second‐order kinetics, and CBM/SCL at 5/1 exhibited the highest swelling capability. The addition of SCL made the water absorption mechanism tend to a non‐Fickian diffusion mode. Then, the niosomal hydrogel was prepared by the optimized gel formulation with the CoQ10‐loaded niosome. It was found that the gel properties were insignificantly affected by the CoQ10 niosomes. The particle sizes of the niosomes in the gel were a little larger than that in aqueous suspension. After storage for 30 days, the CoQ10 retention rate in the niosomal gel remained at 92% (4°C, N‐Gel), representing high stability of CoQ10. [ABSTRACT FROM AUTHOR]

A series of chemically cross-linked microgel composite hydrogels (MCH gels) with excellent toughness and stretchability were prepared using core–shell polymer microspheres as cross-linking junctions. In our strategy, MCH gels are obtained by connecting microspheres with polyacrylamide (PAAm) chains chemically grafted onto their surfaces, where an organic cross-linking agent is completely unnecessary. The mechanical behavior of the MCH gels was analyzed, and superresolution fluorescence microscopy and scanning electron microscopy were used to investigate their toughening mechanism. The results indicated that the homogeneous network structure resulting from the good compatibility between the core–shell microspheres and matrix was an important reason for the excellent toughness of the MCH gels. In addition to interactions among H bonds in the grafted PAAm chains, reversible deformation of the core–shell microspheres acting as cross-linking junctions, which arises from the flexibility of the microspheres, and the effect of cavitation between the microspheres and matrix could also effectively dissipate energy during deformation of the MCH gels. [ABSTRACT FROM AUTHOR]

In this study, multi-sensitive hydrogels with high mechanical strength were successfully prepared by in situ free-radical polymerization of acrylamide, acrylic acid and acryloyloxyethyl trimethyl ammonium chloride monomers in the presence of microgels in aqueous media. Microgels with amine groups on the surface were used as polyfunctional initiating and cross-linking centers to fabricate a network. The microgel-based hydrogels synthesized did not fracture upon loading up to 30 MPa and a strain above 99 % when the water content was about 84 wt%. As for the swelling behaviors of the microgel-based hydrogels, they were susceptible to pH and salt concentration. Meanwhile, deswelling tests indicated that the microgel-based hydrogels had thermo-sensitive properties and under high temperature exhibited a faster shrinking rate, which could be attributed to the solvent channels caused by the shrinkage of microgels due to their thermo-sensitive core. And microgel-based hydrogels with various deswelling rates can be determined by regulating the content and species of microgel. Furthermore, the low extensibility of microgel-based polyampholyte hydrogels could be improved by creating a hybrid network with microgels and a small amount of N,N'-methylenebisacrylamide served as the chemical cross-linkers. The hybrid hydrogels possessed superior compressive strength and simultaneously showed abnormal elongation of up to 1000 %. [ABSTRACT FROM AUTHOR]

Ideal titanium implants are required to participate in bone repair actively to improve in situ osteointegration. However, the traditional surface functionalization methods of titanium implants are difficult to both achieve the active regulation and long-term stability of bioactive components. Here, a novel functionalized titanium which loaded with thymosin β4 (Tβ4) and covered by a hydrogel coating was designed and evaluated. A strong adhesion between the coating and the titanium substrate was realized by the synergistic action of borate ester bonds and surface topological structure. The hydrogel coating also achieved an in vivo adhesion between implant and tissue through hydrogen bonds and borate bonds. In addition, based on the ROS response property of borate bonds, the implant can release Tβ4 in response to the immune reaction of bone healing by regulating the polarization of macrophages, thereby reducing the fibrosis formation around the implant interface and promoting vascularization and osteointegration of bone defects. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: High strength, stimuli-responsive poly(acrylamide) composite hydrogels (PAAm CH gels) were prepared by grafting polymerization of acrylamide (AAm) onto temperature-sensitive core–shell microgels. These microgels, composing of poly(N-isopropylacrylamide) as core and polyvinylamine (PVAm) as shell, were used as both initiator and crosslinker to form a robust three-dimensional network via bonding the poly(acrylamide) (PAAm) backbone. The CH gels exhibited a remarkably rapid shrinking rate and transmittance switch in response to the environmental temperature change, which the conventional chemically cross-linking PAAm hydrogels (PAAm OR) were short of. Even compared to the bulk PNIPAAm hydrogels (PNIPAAm OR) crosslinked with N,N′-methylenebisacrylamide (MBA), the CH gels were featured with faster responsive rate, which could be attributed to the formation of interconnected water transportation channels between the microspheres and PAAm gel matrix due to the fast shrinking of microgels. Moreover, the effects of microgel species and content on swelling and mechanical properties of CH gels were also systematically investigated. The results elaborated that the CH gels could be compressed almost 99% without breaking and completely recovered their original shape when the stress was removed. And the optimized compressive strength of CH gels could be up to 21.94 MPa. Based on the analysis of CH gel mechanical properties, the influence of microsphere content on effective network chains density of CH gels was discussed through rheology measurements. Finally, the essential reinforcement on mechanical properties was mainly contributed to the homogeneous microstructure of hydrogel network and the energy dissipation mechanism of microgels in gel matrix. [Copyright &y& Elsevier]

Abstract: A cationic surfactant monomer, dimethyldodecyl(2-acrylamidoethyl)ammonium bromide (AMQC12) was synthesized. A family of hydrophobic-associating cross-linking hydrogels (HAC-gels) fabricated via the self-assembly of amphiphilic multiblock copolymers of acrylamide and AMQC12 can be synthesized by free-radical aqueous solution micelle copolymerization in the absence of surfactants using the one-pot method. The HAC-gels possessed outstanding mechanical performance, with optimal tensile strength, compressive strength, and elongation at break of 250 kPa, 14 MPa, and 1850%, respectively. Meanwhile, the HAC-gels exhibited self-healing property, and tetrahydrofuran (THF) significantly accelerated their self-healing process. The recovery hysteresis of hydrophobic-associating hydrogels prepared in the presence of surfactants can be eliminated because of homogeneity of the hydrogel network and the dynamic and mobile properties of physical cross-linking junctions. Investigations on the mechanical property and structure evolution of hydrogels revealed that the hydrophobic-associating interaction was the driving force of self-assembly of amphiphilic multiblock copolymers. Furthermore, spherical micelles and macroscopic cross-linking network can be easily switched reversibly by regulating copolymers concentration. [Copyright &y& Elsevier]

Abstract: A circular system is employed in this paper to investigate the swelling behaviors of polyampholyte hydrogels; this circular system can effectively eliminate the disturbance of various factors and keep the surrounding environment constant. It is found that there exists a spontaneous volume transition to the collapsed state of polyampholyte hydrogels, which is attributed to the overshooting effect, and the transition can occur repeatedly under certain conditions. 13C NMR is employed to investigate the swelling behavior of polyampholyte hydrogels. The swelling kinetics of polyampholyte hydrogels under various circular media and various circular runs are also investigated in this paper. All the results suggest that the spontaneous volume transition to the collapsed state of polyampholyte hydrogels is dominated by pure electrostatic interaction between different charges in polymer chains. [Copyright &y& Elsevier]

Abstract: A series of novel polyampholyte superabsorbent nanocomposites with excellent gel strength were synthesized by in situ solution polymerization in aqueous solution. Acrylic acid and acryloyloxyethyl trimethyl ammonium chloride (DAC) were employed as ionic monomers and montmorillonite (MMT) was used as inorganic component. The addition of cationic component could supply the positive charge in the network of nanocomposite and promote the formation of nanostructure of composites due to the interaction between DAC and clay platelets. The performance of polyampholyte nanocomposites were investigated and the result showed that the gel strength of nanocomposite hydrogel in distilled water and 0.9wt% NaCl solution could reach 198.85 and 204.23mJ/g, respectively, which were 13 times of the gel strength of matrix. The investigation of swelling behaviors showed that the nanocomposites had particular swelling behaviors of polyampholytes hydrogel in solution with different pH values and concentration of NaCl. [Copyright &y& Elsevier]

Abstract: Two series of the nanocomposite hydrogels were synthesized by in-situ solution polymerization. One pre-gel solution was obtained by directly dispersing the montmorillonite (MMT) powder into aqueous monomer solution and the other pre-gel solution was obtained by mixing monomer aqueous solution and the dispersion of MMT. The structure and performance of two series of hydrogels in dry state were studied by XRD, Raman spectroscopy, TEM and 27Al MAS NMR. Compressing test results showed that the gel strength of the hydrogels prepared by the latter method was much higher than that by the former method. When acryloyloxyethyl trimethyl ammonium chloride (DAC) was introduced into the system, hydrogels with excellent nanostructure could be synthesized. The result of 27Al MAS NMR suggested that the chemical environment of aluminum in MMT was changed by the introduction of DAC due to the interaction between the groups of DAC and MMT layers. Thus, the combination of copolymerizing with strong polar monomers and using the dispersion of MMT were the effective ways to obtain nanocomposite hydrogel of MMT and ionic monomers. The nanostructure of the hydrogel improved the gel strength, while the swelling ratio of the hydrogel depended on synergic effects of multifunctional groups. [Copyright &y& Elsevier]

The biodegradable polysaccharide hydrogels have attracted much attention due to its biocompatible and non-toxicity. Herein, we report a starch hydrogel synthesized via thiol-ene click reaction between thiol starch (St-SH) and allyl starch (AS). The swelling behaviors, rheological experiment and biodegradable properties of the obtained hydrogel were investigated in details. The chemical structure of functioned starch was confirmed by 1 H-NMR and 13 C-NMR. Moreover, the rheological experiment indicated that starch hydrogel possessed high mechanical strength, and its modulus could be manipulated by the thiol-ene molar ratio. Biodegradation tests revealed that the hydrogel could be biodegradable rapidly in the presence of α-amylase. The biodegradation rate could be controlled by the thiol-ene molar ratio or the concentration of α-amylase. Degradation kinetics from the hydrogel suggested that the degradation/erosion of starch hydrogel come from a combination of both the surface erosion and diffusion mechanisms. [ABSTRACT FROM AUTHOR]

Highlights: [•] Starch-based nanospheres crosslinked hydrogel are fabricate. [•] The hydrogels exhibit a narrow LCST gap. [•] The hydrogels exhibit a high mechanical strength. [•] The properties of the hydrogels can regulate by nanosphere concentrations. [•] The hydrogels are degradable in aqueous medium. [ABSTRACT FROM AUTHOR]

In recent years, magnesium alloys (MgA) have been reckoned as the most promising material of biomedical importance on account of its excellent degradable properties and mechanical properties mimicking natural bone tissues. However, MgA are prone to rapid corrosion under physiological conditions, causing toxicity around the neighboring tissues. In addition, they are susceptible to bacterial colonization, a detrimental factor for medical causes. In this study, antibacterial material coated hydrogel-based micro-patterns were developed on MgA to achieve long-term antibacterial, antifouling, osteogenic, and cell-compatible properties. First, the Mg(OH) 2 nanosheet coating was prepared on the surface of MgA as a physical barrier to prevent the corrosion of MgA. Then the hydrogel micropatterns of poly(alendronate sodium methacrylate)/poly(dimethyldiallylammonium chloride)/poly(ethylene glycol) diacrylate (PALNMA/PDADMAC/PEGDA) of different sizes were constructed on the surface of the Mg(OH) 2 coating using the photomask method. Finally, an intelligently responsive antibacterial material hyaluronic acid/berberine (HA/BBR) was coated on MgA-Mg(OH) 2 -PALNMA/PDADMAC/PEGDA patterns via layer-by-layer self-assembly. The excellent antifouling performance of the samples is attributed to the topological structure of the pattern. Interestingly, as the pattern size of PALNMA/PDADMAC/PEGDA decreases, the antibacterial, antifouling, and cell compatibility properties of the samples gradually improve. UV–Vis spectra and bacterial plate count indicate that HA/BBR coating provide a pH and hyaluronidase (HAase) dual-responsive surface to kill the attached bacteria quickly. Finally, the in vitro experiments demonstrate excellent blood compatibility, cell compatibility and osteogenic properties of the modified MgA samples. Therefore, the intelligent multifunctional assembly of MgA presented here has a promising future in the field of metal implant materials. • AZ31 magnesium alloy is modified into MgA-Mg(OH) 2 -5 μm pattern-HA/BBR assembly. • The MgA-Mg(OH) 2 -5 μm pattern-HA/BBR has long-term stable corrosion resistance and antibacterial properties. • The MgA-Mg(OH) 2 -5 μm pattern exhibits excellent anti-fouling performance due to the pattern size effect. • HA/BBR coating has dual response performance of enzyme and pH. • The MgA-Mg(OH) 2 -5 μm pattern-HA/BBR shows good cell compatibility and osteogenic properties. [ABSTRACT FROM AUTHOR]

Using a facile two-step method, the researchers synthesized a pH-responsive double-network (DN) hydrogel with high strength and toughness, consisting of a B(OH) 4 − linked hydroxypropyl guar gum (HPG) network and a covalently cross-linked polyacrylamide (PAAm) network. The mechanical strength of HPG/PAAm DN gel was investigated as a function of synthesis conditions, HPG content, sodium borate concentration and soaking time. The resulting DN gel exhibited unique pH-responsive properties and excellent mechanical properties, with a fracture stress of 843 kPa, and an excellent extensibility of 1400% (12−14 times its initial length). The relationship between mechanical property and the synergy of HPG and PAAm networks was discussed systematically. The DN gel possessed self-recovery under small deformation, but displayed self-reinforcement under large deformation. [ABSTRACT FROM AUTHOR]

During the completion of a natural gas well, the annular gas migration of the cement paste significantly damages the cement quality. Thus, the cement with self-repairing property has great significance in oil well applications. In this work, chemically cross-linked hydrogels were synthesized by the solution polymerization of acrylamide, acrylic acid, and 2-(dimethylamino)ethyl methacrylate (DMAEMA) with NMBA as cross linker to plug the CO 2 -triggered microcracks in the cement paste. The mechanical strength of the hydrogel (Cu-PMAD) was significantly enhanced by complexation between Cu2+ and the carboxyl group of the hydrogel network. As a self-healing plugging material, Cu-PMAD hydrogel powder was mixed with cement to prepare self-repairing cement slurry. The amphoteric structure of hydrogel was triggered by CO 2 due to the DMAEMA unit of the hydrogel was protonated, and the hydrogel can swell further by the anti-polyelectrolyte effect under CO 2 of nature gas and formation salt-bearing fluid. The good swelling ability and mechanical properties endowed the Cu-PMAD hydrogel with excellent plugging ability for cement microcracks triggered by CO 2. [Display omitted] • The mechanical strength of the gel was significantly enhanced by ionic complexation. • The amphoteric structure was formed of hydrogel triggered by CO 2. • The hydrogel can swell further through amphoteric structure under salts conditions. [ABSTRACT FROM AUTHOR]

Fundamentalunderstanding of the fracture process and tougheningmechanisms of double network (DN) hydrogels is critical for rationaldesign of the next generation of tough DN gels with desirable mechanicalproperties. However, current knowledge of DN gels from synthesis methodsto toughening mechanisms mainly comes from chemically cross-linkedDN gels. Little is known about hybrid physically chemically cross-linkedDN gels. Herein, we synthesize tough DN hydrogels by combining twotypes of cross-linked polymer networks: a physically cross-linkedfirst network of agar and a covalently cross-linked second networkof polyacrylamide (PAM). The resulting Agar/PAM DN gels achieved hightoughness of 500–1000 J/m2. More importantly, wereveal several differences and similarities between hybrid Agar/PAMDN gels and chemically linked PAMPS/PAM DN gels. First, differentfrom the nearly velocity-independent mechanical properties in chemicallylinked DN gels, hybrid Agar/PAM DN gels show velocity-dependent fracturebehaviors and toughness. Second, successive cyclic loading–unloadingtests indicate the continuous fracture of the first agar network,instead of a phase transition from continuous to discontinuous inchemically linked DN gels. Third, Agar/PAM DN gels exhibit differentyielding and necking behaviors from chemically linked DN gels, includingmuch lower yielding stress/strain, no stable necking platform, andsimultaneous necking. We thus propose a chain pulling-out model tointerpret the continuous fracture process of the first agar networkand associated energy dissipation mechanism for hybrid Agar/PAM DNgels. This work strives to provide a better fundamental understandingof structure–property relationship of DN gels, which help todevelop new DN gels with desirable properties. [ABSTRACT FROM AUTHOR]

Bacterial infection treatment and subsequent tissue rebuilding are the main tasks of biomaterial research. To endow implants with antibacterial activity and biological functions, the material systems are usually very complicated and ineffective. Recently, the concept of photobiomodulation (PBM), or low-level laser therapy (LLLT), has attracted increasing attention in tissue repair applications but still has not obtained wide acceptance. Because of the same laser resource, PBM could simultaneously work with 660 nm laser triggered photodynamic therapy (PDT), which will significantly simplify the material system and achieve the multiple functions of antibacterial activity and biological modulation effects. Herein, we attempt to validate the effectiveness of PBM and combine PBM with a PDT-based material system. A catechol motif-modified methacrylated gelatin containing photosensitizer Chlorin e6-loaded mesoporous polydopamine nanoparticles was fabricated (GelMAc/MPDA@Ce6). This hydrogel could be tightly adhered to titanium surfaces to serve as surface coating materials or directly used as dressings. Because of the 660 nm laser-triggered ROS generation property of Ce6, GelMAc/MPDA@Ce6 exhibited a remarkable and rapid antibacterial activity when the laser power was 1 W cm−2. After bacterial elimination, when the power was adjusted to 100 mW cm−2, daily irradiation brought an excellent PBM effect: the fibroblast activation was realized to accelerate wound repair. According to our in vitro and in vivo results, the fabricated hydrogel coating possessed both antibacterial activity and fibroblast activation ability only by adjusting the power of laser irradiation, which will greatly strengthen the confidence of using PBM in broader fields and give a good example to combine PBM with traditional biomaterial design. [ABSTRACT FROM AUTHOR]

Conventional hydrogels freeze and harden at sub-zero temperatures and their mechanical properties are considerably inadequate for practical load-bearing applications. These drawbacks hinder their application possibilities. In this work, we propose a new strategy based on Pickering emulsion polymerization to fabricate novel organohydrogels with antifreeze properties. Ethylene glycol (EG) is introduced into the aqueous phase of the Pickering high internal phase emulsion (HIPE) to effectively inhibit water from freezing. The resulting bicontinuous organohydrogels are prepared through simultaneous polymerization in the external and internal phases to provide enhanced mechanical properties and good hydrophilic-oleophilic properties. Furthermore, the organohydrogels are more stable than conventional hydrogels under ambient conditions and remain unfrozen and mechanically flexible down to −40 °C. Image 108 • Hydrophobic diatomite particles stabilize Pickering HIPEs. • Bicontinuous organohydrogels are fabricated via Pickering HIPEs polymerization. • Ethylene glycol is introduced into the aqueous phase of the Pickering HIPEs to inhibit the freezing of organohydrogels. • The organohydrogels remain unfrozen and mechanically flexible down to −40 °C. [ABSTRACT FROM AUTHOR]