Ionic Crosslinking Research Articles

Biopolymer pectin with calcium ion crosslinker as biocompatiable electrolyte for energy storage applications

Biopolymer electrolyte-based electrochemical devices for charge storage, such as supercapacitors and rechargeable batteries, attract wide attention. This study proposes that thin, transparent, and flexible polymer electrolytes can be fabricated using pectin, poly (ethylene glycol) (PEG), and calcium chloride (CaCl2) by solvent casting. CaCl2 plays a vital role as a crosslinker to form the film. The developed pectin/CaCl2 (PeO) and PEG/pectin/CaCl2 (PPe) polymer films are subjected to Fourier transform infrared analysis (FTIR) to confirm polymer matrix formation with the salt ions. The biopolymer membrane's glass transition temperature (Tg) is analyzed using differential scanning calorimetry (DSC). Symmetric supercapacitor devices were fabricated using activated carbon (AC) as electrode material, functionalized carbon fiber as a current collector, and pectin polymer films (PeO and PPe) as a gel electrolyte/separator. The symmetrical device with AC as the electrode and PPe as the electrolyte [AC||PPe||AC] exhibited a specific capacitance of 879 mF cm−2 at 15 mA cm−2, which is considerably higher than the similar device with PeO as electrolyte [AC||PeO||AC]. The cyclic stability of the [AC||PPe||AC] supercapacitor device was 83 % over 5000 cycles. Three supercapacitor devices connected in series is capable to glow 5 light-emitting diodes (LEDs). Good storage and stability indicate that the PPe is suitable as a gel polymer electrolyte material. This polymer electrolyte has excellent prospects in practical applications of all-solid-state, flexible, portable, and biocompatible energy storage devices.

Mussel-inspired resilient hydrogels with strong skin adhesion and high-sensitivity for wearable device

Stretchable and self-adhesive conductive hydrogels hold significant importance across a wide spectrum of applications, including human–machine interfaces, wearable devices, and soft robotics. However, integrating multiple properties, such as high stretchability, strong interfacial adhesion, self-healing capability, and sensitivity, into a single material poses significant technical challenges. Herein, we present a multifunctional conductive hydrogel based on poly(acrylic acid) (PAA), dopamine-functionalized pectin (PT-DA), polydopamine-coated reduction graphene oxide (rGO-PDA), and Fe3+ as an ionic cross-linker. This hydrogel exhibits a combination of high stretchability (2000%), rapid self-healing (~ 94% recovery in 5 s), and robust self-adhesion to various substrates. Notably, the hydrogel demonstrates a remarkable skin adhesion strength of 85 kPa, surpassing previous skin adhesive hydrogels. Furthermore, incorporating rGO within the hydrogel network creates electric pathways, ensuring excellent conductivity (0.56 S m–1). Consequently, these conductive hydrogels exhibit strain-sensing properties with a significant increase in gauge factor (GF) of 14.6, covering an extensive detection range of ~ 1000%, fast response (198 ms) and exceptional cycle stability. These multifunctional hydrogels can be seamlessly integrated into motion detection sensors capable of distinguishing between various strong or subtle movements of the human body.

Hypercrosslinked Hydrogel Composite Membranes Targeted for Removal of Volatile Organic Compounds via Selective Solution-Diffusion in Membrane Distillation.

Membrane distillation (MD) has attracted considerable interest in hypersaline wastewater treatment. However, its practicability is severely impeded by the ineffective interception of volatile organic compounds (VOCs), which seriously affects the product water quality. Herein, a hypercrosslinked alginate (Alg)/aluminum (Al) hydrogel composite membrane is facilely fabricated via Alg pregel formation and ionic crosslinking for efficient VOC interception. The obtained MD membrane shows a sufficient phenol rejection of 99.52% at the phenol concentration of 100 ppm, which is the highest rejection among the reported MD membranes. Moreover, the hydrogel composite membrane maintains a high phenol interception (>99%), regardless of the feed temperature, initial phenol concentration, and operating time. Diffusion experiments and molecular dynamics simulation verify that the selective diffusion is the dominant mechanism for VOCs-water separation. Phenol experiences a higher energy barrier to pass through the dense hydrogel layer compared to water molecules as the stronger interaction between phenol-Alg compared with water-Alg. Benefited from the dense and hydratable Alg/Al hydrogel layer, the composite membrane also exhibits robust resistance to wetting and fouling during long-term operation. The superior VOCs removal efficiency and excellent durability endow the hydrogel composite membrane with a promising application for treating complex wastewater containing both volatile and nonvolatile contaminants.

The impact of synergistic action of methacrylic acid/zinc oxide/carbon nanotubes on metal Friction and wear

The continuous operation of essential refining equipment, internal mixers, leads to wear on their end faces, resulting in an increased gap between the mixer chamber and the end face. This, in turn, causes material leakage, reducing mixing efficiency and adversely impacting rubber performance. Therefore, investigating metal wear on the mixer's end face during the mixing process is essential. Scholars have introduced dynamic covalent bonds into rubber molecular chains, bestowing self-repairing capabilities upon the materials. This innovation has significant implications for extending rubber lifespan and lowering production costs. It involves adding methacrylic acid (MAA) and excess zinc oxide (ZnO) to construct an ionic crosslinking network, limiting covalent crosslinking of rubber molecules and enabling in-situ polymerization of MAA/ZnO, resulting in self-repairing properties. However, it is crucial to consider corrosive wear induced by MAA's strong acidity on metals. This study combines MAA, ZnO, and multi-walled carbon nanotubes (MWCNTs) through mechanical mixing to create a composite material called zinc methacrylate (ZDMA)/MWCNTs/rubber. The research investigates the in-situ synthesis mechanism of MAA and ZnO and the synergistic mechanism of ZDMA and MWCNTs. The study analyzes the impact of MWCNTs additive amount on the frictional wear of the internal mixer's metal end face. During the mixing process, ZDMA is grafted and polymerized onto rubber's macromolecular chains, forming ionic pairs with strong electrostatic interactions, creating a primarily reversible supramolecular network dominated by ion crosslinking. This ion crosslinking network, along with the three-dimensional mesh structure of MWCNTs, establishes a stable spatial structure within the rubber matrix. The study reveals that increasing the MWCNTs content to 3 phr reduces the aggregation of SiO2 particles and ZDMA granules within the rubber matrix, resulting in reduced friction coefficients, roughness, and wear rates of the metal. However, exceeding 3 phr of MAA content leads to excessive MWCNT aggregation within the rubber matrix, increasing wear rates, roughness, and friction coefficients due to hindrance of rubber macromolecular chain crosslinking and reduced SiO2 particle dispersion within the rubber matrix. These findings provide valuable insights into the dynamics of frictional wear in internal mixers.

Anti-freezing and moisturizing PAA/PEDOT: PSS ionogels with multiple stimulus responses for flexible wearable electronics

Hydrogel is a promising material for wearable electronics due to its good mechanical properties, electrical conductivity and body adaptability. However, subzero freezing and water loss under high temperature or prolonged placement are great challenges for hydrogels. Here, polyacrylic acid / poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PAA/PEDOT: PSS) ionogels were designed by entangling PAA and PEDOT: PSS chains with each other in a binary solvent system of water and ionic liquid (IL) and chemical cross-linking by N, N’-methylene bisacrylamide (MBA). It has excellent mechanical properties (8.3 kPa, > 500 %), skin-adapted Young's modulus (<10 kPa), high conductivity (8.06 S·m−1), and strong adhesion (13.3 kPa). Ionogel has a sensitive response as a sensor (GF = 2.08, 0–200 %; GF = 3.64, 200–400 %; GF = 4.58, 400–510 %). Especially, the freeze-resistance and long-term moisturizing properties make ionogels exhibit long-lasting and robust utility. As a scalable application platform, we demonstrate the potential applications of this novel ionogel as a body-conformable electronic product in a series of conceptual demonstrations, including full range of human motion response, human–machine interaction (HMI), temperature signal detection and TENG device assembly.

Novel films of pectin extracted from ambarella fruit peel and jackfruit seed slimy sheath: Effect of ionic crosslinking on the properties of pectin film

Here, we prepared ionically crosslinked films using pectin extracted from agro-wastes, specifically ambarella peels (AFP) and jackfruit seed slimy sheath (JFS). Physiochemical properties of pectins, including moisture content, molecular weight (Mw), degree of esterification (DE), and galacturonic acid (GA), were analyzed. Optimal extraction was determined, i.e., citric acid concentration 0.3 M, time 60 min, solid/liquid ratio 1:25, and temperature 90 °C for AFP or 85 °C for JFS. Pectin yields under these conditions were 29.67 % ± 0.35 % and 29.93 ± 0.49 %, respectively. AFP pectin revealed Mw, DE, and GA values of 533.20 kDa, 67.08 % ± 0.68 %, and 75.39 ± 0.82 %, while JFS pectin exhibited values of 859.94 kDa, 63.04 % ± 0.47 %, and 78.63 % ± 0.71 %, respectively. The pectin films crosslinked with Ca2+, Cu2+, Fe3+, or Zn2+ exhibited enhanced tensile strength and Young's modulus, along with reduced elongation at break, moisture content, water solubility, water vapor permeability, and oxygen permeability. Structural analyses indicated metal ions were effectively crosslinked with carboxyl groups of pectin. Notably, the Cu2+-crosslinked film demonstrated superior water resistance, mechanical properties, and exhibited the highest antioxidant and antibacterial activities among all tested films. Therefore, the pectin films represent a promising avenue to produce eco-friendly food packaging materials with excellent properties.

Hierarchically aligned channels in the distillation membrane enable efficient solar powered desalination

Solar-powered interfacial evaporation attracts enormous attention to solve the water crisis as a low-energy consumption, high energy conversion efficiency, and environmental-friendliness technology. Balancing water transport, water content and interfacial temperature is critical to promote evaporation performance. However, fabrication methods and investigation of dedicatedly-designed structures and channel sizes for solar-powered interfacial evaporation have been rarely reported. Herein, we propose to employ vertically aligned channels with hierarchy sizes to modulate water evaporation and energy efficiency. This unique structure is fabricated by a three-step procedure including freeze-drying, ion cross-linking, and hydrogen bond reconstruction in sequence, which achieves a membrane with vertically aligned channels ranging from 1 nm to tons of micrometers. Our solar-powered distillation membrane with finely-modulated hierarchical structure exhibits a high pure water generation rate of 2.37 kg m−2 h−1 under one sun illumination. Even when treated with seawater, it can achieve a capacity of 2.34 kg m−2 h−1 (10 wt% seawater) and stabilize a high evaporation rate for at least 50 h, which is superior to most reported solar empowered distillation membranes. Our distillation membrane features a high mechanical strength and low cost, making it an appealing candidate for the actual application in desalination.

Elastomers mechanically reinforced and toughened with CO2 gas

Gas-responsive polymers have recently attracted considerable interest as unconventional smart materials that provide a new path toward the utilization of specific gases including CO2. Herein, we report gas-responsive elastomers that enhance mechanical properties, such as modulus, strength, stretchability, and toughness with CO2 gas. Various types of amine groups are introduced into polydimethylsiloxane elastomers to achieve the gas-induced mechanical reinforcement. In these elastomers, the amines form ionic crosslinks with CO2 gas that mechanically strengthen the materials. Furthermore, nanodomains formed via microphase separation of the ionic components behave similarly to viscoelastic nanofillers that dissipate a large amount of energy during deformation, thereby remarkably toughening the elastomers. Surprisingly, the fracture energy of the elastomer with diamine increases ~35 times in CO2 gas compared with that in N2 gas. Furthermore, the elastomers sensitively respond even to CO2 gas concentrations as low as 10 % and are remarkably toughened. Our design concept is widely applicable to the CO2 reinforcement of other polymers, such as polyethylene.

Effect of cross-linking agents on sodium alginate-based quercetin beads: physicochemical properties and controlled release kinetics

Alginates have a variety of biological, physical, and chemical properties that can be modified to meet a specific purpose. Ionic crosslinking is an easy method of alginate modification. This study examined the ionic crosslinking agents (Ca2+, Ba2+, Mg2+) on swelling ratio, water solubility, and % sol-gel fraction of modified alginate. The performance of the modified alginate used to encapsulate quercetin, such as % encapsulation efficiency (% EE), % release of quercetin, and quercetin release kinetics were examined. The variables used in this study were the concentration of alginate and ionic crosslinking agents. At 3% alginate concentration and 0.3 M, ionic crosslinking agent concentration positively correlated with swelling ratio and water solubility. In contrast, the ionic crosslinking agent that positively correlates to the % sol-gel fraction is Ca2+. Encapsulation of quercetin using a crosslinking agent with ion Ca2+ and 2.5 ppm of quercetin concentration showed the highest % EE of 87%. Modified alginate induced quercetin release from beads at pH 1.4 and 7. The release of quercetin from modified alginate followed the Korsmeyer-Peppas kinetic model (R2 &gt;0.99). The results of the FTIR analysis confirmed that a new peak at 1271 cm-1 was C-O-C characteristic of quercetin, indicating quercetin loaded on encapsulated beads. The morphological analysis showed that the surface of modified alginate (Ca-Ag/Ba-Ag/Mg-Ag) was rough and porous. This study established that modified alginate using different ionic crosslinking agents can be a suitable matrix for encapsulating quercetin.

Boron nitride-alginate coordination interactions enabling hydrogels with enhanced mechanical strength and heat resistance

Developing large-scale hydrogels with high tensile strength and robust mechanical properties is an intricate challenge of great industrial significance. In this study, we demonstrate an efficient method for producing nanocomposite hydrogels with extraordinary mechanical properties. Our approach involves a two-step process: an initial stage of pre-cross-linking boron nitride (BN)-enriched pre-gel sodium alginate, followed by cross-linking with metal ions. In stark contrast to conventional sodium alginate hydrogels (SA), our newly formulated ‘BS hydrogel’ exhibited an impressive tensile strength exceeding 41 MPa and improved thermal resistance. Moreover, the reconstituted BS hydrogel exhibited tensile strengths ranging from 47 to 96 MPa and elastic moduli ranging from 199 to 1184 MPa, depending on the cross-linking metal ions. These findings indicate the multifaceted potential of the BS hydrogel, which is poised to revolutionize many applications and represents a significant step forward in hydrogel technology for industrial applications.

Sodium alginate/polyvinyl alcohol semi-interpenetrating hydrogels reinforced with PEG-grafted-graphene oxide

Semi-interpenetrating polymer network (SIPN) hydrogels composed of sodium alginate/poly (vinyl alcohol), reinforced by PEG-grafted-graphene oxide (GO-g-PEG) were prepared by ionic crosslinking of sodium alginate. The impact of grafted PEG molecular weight with two molecular weights, i.e. 400 and 2000 g/mol, and component composition were studied on the morphology, swelling behavior, mechanical and dynamic properties. SEM observation showed fine dispersion and distribution of GO-g-PEG throughout the hydrogel indicating a good interaction of particles with the components. Our results revealed that although incorporating GO-g-PEG increases the water content, it significantly enhances the mechanical properties, i.e. tensile modulus, elongation at break, and fracture toughness with a more pronounced impact at higher PEG molecular weight. As a result, the tensile modulus and the elongation at break increased by 270 % and 28 %, respectively. The SA/PVA SIPN hydrogels reinforced with the GO-g-PEG exhibit a non-linear elastic behavior with a toe at low strains. This behavior is attributed to the unique structural features of SIPN hydrogels and the orientation of GO-g-PEG particles with proper interaction with the components. The small amplitude oscillatory shear was also performed to further study the impact of SA, PVA, and GO-g-PEG compositions on the microstructure of hydrogels.

Effects of miR-214 on adenosine A2A receptor and carboxymethyl chitosan nanoparticles on the function of keloid fibroblasts and their mechanisms

This work prepared and investigated the impact of carboxymethyl chitosan nanoparticles (MC-NPs) on the proliferative capability of keloid fibroblasts (KFBs) while analyzing the mechanistic roles of miR-214 and adenosine A2A receptor (A2AR) in fibroblasts within hypertrophic scars. MC-NPs were synthesized through ion cross-linking, were characterized using transmission electron microscopy (TEM) and laser particle size scattering. The influence of MC-NPs on the proliferation capacity of KFBs was assessed using the MTT method. Changes in the expression levels of miR-214 and A2AR in KFBs, normal skin fibroblasts (NFBs), hypertrophic scar tissue, and normal skin tissue were analyzed. KFBs were categorized into anti-miR-214, anti-miR-NC, miR-214 mimics, miR-NC, si-A2AR, si-con, anti-miR-214+ si-con, and anti-miR-214+ si-A2AR groups. Bioinformatics target prediction was conducted to explore the interaction between miR-214 and A2AR. Real-time quantitative PCR and immunoblotting (WB) were employed to detect the expression levels of miR-214, A2AR, apoptotic protein Bax, and TGF-β in different cells. Cell counting kit-8 (CCK8) and flow cytometry were employed to assess cell proliferation activity and apoptosis. The results indicated that MC-NPs exhibited spherical particles with an average diameter of 236.47 ± 4.98 nm. The cell OD value in the MC-NPs group was lower than that in KFBs (P < 0.05). The mRNA levels of miR-214 in KFBs and hypertrophic scar tissue were lower than those in NFBs and normal tissue (P < 0.001), while the mRNA and protein levels of A2AR were significantly elevated (P < 0.05). Compared to the control group and anti-miR-NC, the anti-miR-214 group showed significantly increased cell OD values and Bcl-2 protein expression (P < 0.001), decreased levels of apoptotic gene Bax protein, TGF-β gene mRNA, and protein expression (P < 0.001). Continuous complementary binding sites were identified between miR-214 and A2AR. Compared to the control group, the si-A2AR group exhibited a significant decrease in A2AR gene mRNA and protein expression levels (P < 0.001), reduced cell viability (P < 0.001), increased apoptosis rate (P < 0.001), and a significant elevation in TGF-β protein expression (P < 0.001). miR-214 targetedly regulated the expression of A2AR, inducing changes in TGF-β content, promoting the proliferation of keloid fibroblasts, and inhibiting cell apoptosis.

Strong and tough poly(vinyl alcohol)/xanthan gum-based ionic conducting hydrogel enabled through the synergistic effect of ion cross-linking and salting out

The mechanical properties of ionic conductive hydrogels (ICHs) are generally inadequate, leading to their susceptibility to breakage under external forces and consequently resulting in the failure of flexible electronic devices. In this work, a simple and convenient strategy was proposed based on the synergistic effect of ion cross-linking and salting out, in which the hydrogels consisting of polyvinyl alcohol (PVA) and xanthan gum (XG) were immersed in zinc sulfate (ZnSO4) solution to obtain ICHs with exceptional mechanical properties. The salt-out effects between PVA chains and SO42− ions along with the cross-linked network of XG chains and Zn2+ ions contribute to the desirable mechanical properties of ICHs. Notably, the mechanical properties of ICHs can be adjusted by changing the concentration of ZnSO4 solution. Consequently, the optimum fracture stress and the fracture energy can reach 3.38 MPa and 12.13 KJ m−2, respectively. Moreover, the ICHs demonstrated a favorable sensitivity (up to 2.05) when utilized as a strain sensor, exhibiting an accurate detection of human body movements across various amplitudes.

Wet spinning of chitin nanowhiskers: Effects of electrolyte composition in coagulation baths on mechanical properties and nanowhisker orientation

AbstractFibers composed solely of chitin nanowhiskers (ChNWs) with extreme uniaxial orientation can be successfully wet‐spun into coagulation baths containing 70% ethanol and various types of electrolytes (LiCl, HCl, NaCl, and MgSO4) with ionic strengths (J) of 0.075–0.3. The obtained fibers exhibited high ChNW orientation with degrees of orientation (S) ranging from 0.77 to 0.96. Fibers produced using NaCl‐containing coagulation baths contained residual NaCl crystals that were subsequently removed by rinsing. In contrast, LiCl and MgSO4, which originated from the corresponding baths and similarly remained within the fibers, did not crystallize due to hygroscopic deliquescence and the adaptation of SO42− ions for potential ionic crosslinking, respectively. Spinning with LiCl‐containing baths yielded fibers with maximum Young's modulus, stress at break, and strain at break of 7.9 ± 0.6 GPa, 58.8 MPa, and 1.13%, respectively. These mechanical properties of the unwashed fibers improved with J, while washing out the residual electrolytes and subsequent drying led to a decrease in the Young's modulus and an increase in the stress at break and strain at break. An increase in S was observed only in the fibers obtained using baths with J ≥ 0.3.

Preparation and characterization of nisin-loaded chitosan nanoparticles functionalized with DNase I for the removal of Listeria monocytogenes biofilms.

Listeria monocytogenes biofilms represent a continuous source of contamination, leading to serious food safety concerns and economic losses. This study aims to develop novel nisin-loaded chitosan nanoparticles (CSNPs) functionalized with DNase I and evaluate its antibiofilm activity against L. monocytogenes on food contact surfaces. Nisin-loaded CSNPs (CS-N) were first prepared by ionic cross-linking, and DNase I was covalently grafted on the surface (DNase-CS-N). The NPs were subsequently characterized by Zetasizer Nano, transmission electron microscopy, Fourier transform infrared (FT-IR), and X-ray diffraction (XRD). The antibiofilm activity of NPs was evaluated against L. monocytogenes on polyurethane (PU). The DNase-CS-N was fabricated and characterized with quality attributes (particle size-427.0±15.1nm, polydispersity [PDI]-0.114±0.034, zeta potential-+52.5±0.2mV, encapsulation efficiency-46.5%±3.6%, DNase conjugate rate-70.4%±0.2). FT-IR and XRD verified the loading of nisin and binding of DNase I with chitosan. The DNase-CS-N caused a 3 logcolony-forming unit (CFU)/cm2 reduction of L. monocytogenes biofilm cells, significantly higher than those in CSNPs (1.4log), CS-N (1.8log), and CS-N in combination with DNase I (2.2log) treatment groups. In conclusion, nisin-loaded CSNPs functionalized with DNase I were successfully prepared and characterized with smooth surface and nearly spherical shape, high surface positive charge, and good stability, which is effective to eradicate L. monocytogenes biofilm cells on food contact surfaces, exhibiting great potential as antibiofilm agents in food industry. PRACTICAL APPLICATION: Listeria monocytogenes biofilms are a common safety hazard in food processing. In this study, novel nanoparticles were successfully constructed and are expected to be a promising antibiofilm agent in the food industry.

Quercetin-crosslinked chitosan nanoparticles: a potential treatment for allergic rhinitis

Allergic rhinitis (AR) remains a major health problem worldwide. Compared with traditional oral drugs, nasal administration avoids first-pass metabolism and achieve faster and more effective efficacy. In this study, we used the ion crosslinking method to prepare quercetin–chitosan nasal adaptive nanomedicine (QCS) delivery system and evaluated in the treatment of allergic rhinitis mice models. The obtained positively charged nanoparticles with a particle size of 229.2 ± 0.2 nm have excellent characteristics in encapsulation efficiency (79.604%), drug loading rate (14.068%), drug release (673.068 μg) and stability(> 7 days). Excitingly, QCS treatment significantly reduced the number of sneezing and nasal rubbing events in AR mice, while reducing the levels of inflammatory factors such as immunoglobulin E (IgE), interleukin (IL)-17, tumor necrosis factor (TNF)-α, and (IL)-6 to alleviate AR symptoms. Hematoxylin–eosin (HE) staining also showed the damaged nasal mucosa was improved. These experimental results suggest that QCS can effectively suppress allergic inflammation in a mouse model and hold promise as a therapeutic option for allergic rhinitis.

Construction of a PEGDA/chitosan hydrogel incorporating mineralized copper-doped mesoporous silica nanospheres for accelerated bone regeneration

Hydrogels, integrating diverse biocompatible materials, have emerged as promising candidates for bone repair applications. This study presents a double network hydrogel designed for bone tissue engineering, combining poly(ethylene glycol) diacrylate (PEGDA) and chitosan (CS) crosslinked through UV polymerization and ionic crosslinking. Concurrently, copper-doped mesoporous silica nanospheres (Cu-MSNs) were synthesized using a one-pot method. Cu-MSNs underwent additional modification through in-situ biomineralization, resulting in the formation of an apatite layer. Polydopamine was employed to facilitate the deposition of Calcium (Ca) and Phosphate (P) ions on the surface of Cu-MSNs (Cu-MSNs/PDA@CaP). Composite hydrogels were created by integrating varied concentrations of Cu-MSNs/PDA@CaP (25, 50, 100, 150, 200 μg/mL). Characterization unveiled distinctive interconnected porous structures within the composite hydrogel, showcasing a notable 169.6 % enhancement in compressive stress (elevating from 89.01 to 240.19 kPa) compared to pure PEGDA. In vitro biocompatibility experiments illustrated that the composite hydrogel maintained elevated cell viability (up to 106.6 %) and facilitated rapid cell proliferation over 7 days. The hydrogel demonstrated a substantial 57.58 % rise in ALP expression and a surprising 235.27 % increase in ARS staining. Moreover, it significantly enhanced the expression of crucial osteogenic genes, such as run-related transcription factors 2 (RUNX2), collagen 1a1 (Col1a1), and secreted phosphoprotein 1 (Spp1), establishing it as a promising scaffold for bone regeneration. This study shows how Cu-MSNs/PDA@CaP were successfully integrated into a double network hydrogel, resulting in a composite material with good biological responses. Due to its improved characteristics, this composite hydrogel holds the potential for advancing bone regeneration procedures.

Synchronously Enhancing Mechanical Strength and Conductivity of MXene Nanofluidic Fibers with Multivalent Ion Crosslinking

AbstractDeveloping high‐performance nanofluidic fibers with synergetic ionic and electric conductivities is promising for human–machine interface interaction. In such a scenario, inter‐ and intra‐forces in constituent flakes are recognized as crucial factors in determining the derived nanofluidic fiber performance. In this work, the rheological properties of Ti3C2Tx MXene solution are systematically optimized by regulating the electrostatic interaction via introducing multivalent metal cations. As a result, such multivalent cations trigger ionic crosslinking and remarkably strengthen the interaction force between nanosheets, which even forms into a tight fiber‐shaped gel network. A series of cations, such as K+, Na+, Mg2+, Zn2+, and Al3+, are introduced to enhance the ionic cross‐linking between interconnected flakes. The thus‐prepared Zn2+‐Ti3C2Tx fiber exhibits a remarkable electrical conductivity of 11 200 S cm−1, a tensile strength of 252 MPa, and an ionic conductivity of 2.51 × 10−3 S cm−1. This multivalent cation crosslinking strategy could offer some insights into developing functional nanofluidic fibers for wearable or healthcare applications.

Iron oxide nanoclusters formed by acid-induced in situ calcium ion cross-linking for targeted magnetic resonance imaging of glioblastoma

Contrast agents (CAs) enhanced magnetic resonance imaging (MRI) are potential candidates for the effective diagnosis of glioblastoma (GBM). However, the invasiveness and high heterogeneity of GBM interfere the effectiveness of most CAs. Compared with the conventional CAs with “always on” contrast signals, stimulus-responsive CAs that alter the MR signal in response to a specific change in their surrounding environment acquire the capability to achieve accurate diagnosis of GBM. In this study, inspired by that 1) nanocomposites can be formed by simple and controllable cross-linking anion-rich materials via multivalent cations; 2) and calcium phosphate (CaP) with good biocompatibility can be degraded triggered by acid and release divalent Ca2+, an unprecedented acid-responsive nano-CA was designed for targeted MRI of GBM. The acid-responsive targeted nano-CA (DANG-SPIO@CaP) was prepared by coating CaP on the surface of polyacrylic acid (PAA)-coated ultra-small superparamagnetic iron oxide (PAA/SPIO) nanoparticles, and then modified with the GBM-targeting DANG peptide. DANG-SPIO@CaP has good stability and relatively low T2 relaxivity at the physiological condition. However, under the weakly acidic condition in tumor microenvironment, the CaP shell of DANG-SPIO@CaP degrades, and the released Ca2+ will cross-link the exposed PAA/SPIO to form large nanoclusters with high T2 relaxivity. Consequently, DANG-SPIO@CaP can specifically navigate to GBMs, undergo the in situ acid-responsive degradation and reaggregation processes and form large nanoclusters with stronger T2 enhancing effect, allowing the locations of GBMs to be clearly recognized and even the features of different GBMs to be revealed.

Enzyme-functionalized hydrogel film for extracorporeal uric acid reduction.

Enzyme replacement therapy for hyperuricemia treatment has been proven effective for critical state hyperuricemia patients. Still, direct administration of recombinant uricase can induce several fatal side effects. To circumvent this drawback, hydrogel protein carriers can be used in platforms for extracorporeal treatment such as microscale-based devices. In this work, calcium alginate and poly-(vinyl alcohol) hydrogel films were studied for their urate oxidase immobilization and uric acid reduction, which could be implemented in microscale-based extracorporeal devices. A mathematical model was developed in conjunction with uric acid reduction experiments to evaluate the influence of mass transfer and reaction parameters in the Michaelis-Menten kinetic expression. Alginate hydrogels prepared with crosslinker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-(hydroxysuccinimide) offered superior diffusivity of uric acid in the gel matrix at the maximum value of 1.98 × 10-11 m2 /s compared with alginate prepared solely from ionic crosslinking with 5.31 × 10-12 m2 /s at the same alginate concentration. The maximum value of νmax was experimentally determined at 7.78 × 10-5 mol/(m3 s). A 3% sodium alginate hydrogel with crosslinkers yielded the highest reduction of uric acid at 92.70%. The mathematical model demonstrated an excellent prediction of uric acid conversion suggesting potential use of the model for formulation and maximizing the therapeutic performance of functionalized hydrogels.