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Tissue engineered heart valves (TEHVs) demonstrates the potential for tissue growth and remodel, offering particular benefit for pediatric patients. A significant challenge in designing functional TEHV lies in replicating the anisotropic mechanical properties of native valve leaflets. To establish a biomimetic TEHV model, we employed melt-electrowriting (MEW) technology to fabricate an anisotropic PCL scaffold. By integrating the anisotropic MEW-PCL scaffold with bioactive hydrogels (GelMA/ChsMA), we successfully crafted an elastic scaffold with tunable mechanical properties closely mirroring the structure and mechanical characteristics of natural heart valves. This scaffold not only supports the growth of valvular interstitial cells (VICs) within a 3D culture but also fosters the remodeling of extracellular matrix of VICs. The in vitro experiments demonstrated that the introduction of ChsMA improved the hemocompatibility and endothelialization of TEHV scaffold. The in vivo experiments revealed that, compared to their non-hydrogel counterparts, the PCL-GelMA/ChsMA scaffold, when implanted into SD rats, significantly suppressed immune reactions and calcification. In comparison with the PCL scaffold, the PCL-GelMA/ChsMA scaffold exhibited higher bioactivity and superior biocompatibility. The amalgamation of MEW technology and biomimetic design approaches provides a new paradigm for manufacturing scaffolds with highly controllable microstructures, biocompatibility, and anisotropic mechanical properties required for the fabrication of TEHVs., (© 2024. The Author(s).)

Hyaluronic acid (HA) hydrogel is preferred for biomedicine applications, as it possesses biodegradability, biocompatibility, and cell-regulated capacity as well as high hydration nature similar to the native extracellular matrix. However, HA hydrogel fabricated via a 3D printing technique often faces poor printing properties. In this study, maleiated sodium hyaluronate (MHA) with a high substituted degree of the acrylate group (i.e., 2.27) and thiolated sodium hyaluronate (SHHA) were synthesized. By blending these modified HAs, the MHA/SHHA hydrogels were prepared via pre-crosslinking through thiol-acrylate Michael addition and subsequently covalent crosslinking using thiol-acrylate and acrylate-acrylate photopolymerization mechanisms. Rheological properties, swelling behaviors, and mechanical properties can be modulated by altering the molar ratio of the thiol group and acrylate group. The results showed that the MHA/SHHA hydrogel precursors have rapidly gelling capacity and improved compressive strength. Based on these results, high-resolution hydrogel scaffolds with good structural stability were prepared by extrusion-based 3D printing. This HA hydrogel is cytocompatible and capable of supporting adherence of L929 cells, indicating its great potential for tissue engineering scaffolds.

Chitosan hydrogel have presented great potential in biomedical applications due to its biocompatibility, biodegradability and characteristic similarity to native extracellular matrix. However, 3D printing of chitosan hydrogel often suffers from weak formability and poor mechanical property, limiting its further utilization. In this study, a novel chiotsan hydrogel is prepared from maleic chitosan (MCS) with high acrylate group substitution (i.e. 1.67) and thiol-terminated poly (ethylene glycol) (TPEG) via step-chain growth photopolymerization approach, which can overcome significantly the oxygen inhibition effect. Rheological property, microstructure, mechanical properties and in vitro degradation can be regulated by changing the thiol/acrylate molar ratio. There is strong intermolecular action between MCS and TPEG. Notably, photopolymerized MCS/TPEG hydrogel exhibited ~2-fold and ~ 10-fold increase in gelling rate and compressive strength, respectively, compared to pure chitosan hydrogel. Based on these results, 3D printing of chitosan hydrogel fabricated by simultaneous extrusion deposition and thiol-acrylate photopolymerization, demonstrates printing accuracy and improved scaffold stability. This 3D printing of chitosan hydrogel shows no cytotoxicity and can support adherence of L929 cells, suggesting its potential in biomedical applications such as tissue engineering and drug delivery., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Natural hydrogels are widely investigated for biomedical applications because of their structures similar to extracellular matrix of native tissues, possessing excellent biocompatibility and biodegradability. However, they are often susceptible to mechanical disruption. In this study, self-healing hyaluronic acid (HA) hydrogels are fabricated through a facile dynamic covalent Schiff base reaction. Dialdehyde-modified HA (AHA) precursor was synthesized, and then the AHA/cystamine dihydrochloride (AHA/Cys) hydrogels were formed by blending AHA and Cys at acidic pH levels. By varying Cys to AHA ratio, the hydrogel morphology, swelling and kinetics of gelation could be controlled. Gelation occurred fast, which was predominantly attributed to Schiff base reaction between the dialdehyde groups on AHA and amimo groups on Cys. The hydrogel exhibited improved mechanical properties with increase in Cys content. Furthermore, due to dynamic imine bonds, this hydrogel demonstrated excellent self-healing ability based on the stress after mechanical disruption. Also, it was found to be pH-responsive and injectable. Taken together, this kind of hyaluronic acid hydrogel can provide promising future for various biomedical applications in drug delivery, bioprinting, smart robots and tissue regeneration., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Commercial or clinical tissue adhesives are currently limited due to their weak bonding strength on wet biological tissue surface, low biological compatibility, and slow adhesion formation. Although catechol-modified hyaluronic acid (HA) adhesives are developed, they suffer from limitations: insufficient adhesiveness and overfast degradation, attributed to low substitution of catechol groups. In this study, we demonstrate a simple and efficient strategy to prepare mussel-inspired HA hydrogel adhesives with improved degree of substitution of catechol groups. Because of the significantly increased grafting ratio of catechol groups, dopamine-conjugated dialdehyde-HA (DAHA) hydrogels exhibit excellent tissue adhesion performance (i.e., adhesive strength of 90.0 ± 6.7 kPa), which are significantly higher than those found in dopamine-conjugated HA hydrogels (∼10 kPa), photo-cross-linkable HA hydrogels (∼13 kPa), or commercially available fibrin glues (2-40 kPa). At the same time, their maximum adhesion energy is 384.6 ± 26.0 J m -2 , which also is 40-400-fold, 2-40-fold, and ∼8-fold higher than those of the mussel-based adhesive, cyanoacrylate, and fibrin glues, respectively. Moreover, the hydrogels can gel rapidly within 60 s and have a tunable degradation suitable for tissue regeneration. Together with their cytocompatibility and good cell adhesion, they are promising materials as new biological adhesives.

Hydrogels composed of natural materials exhibit great application potential in artificial scaffolds for cartilage repair as they can resemble the extracellular matrices of cartilage tissues comprised of various glycosaminoglycan and collagen. Herein, the natural polymers with vinyl groups, i.e. maleilated chitosan (MCS) and methacrylated silk fibroin (MSF) micro/nanoparticles, were firstly synthesized. The chemical structures of MCS and MSF micro/nanoparticles were investigated using Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance ( 1 H NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Then MCS/MSF micro/nanocomposite hydrogels were prepared by the photocrosslinking of MCS and MSF micro/nanoparticles in aqueous solutions in the presence of the photoinitiator Darocur 2959 under UV light irradiation. A series of properties of the MCS/MSF micro/nanocomposite hydrogels including rheological property, equilibrium swelling, sol content, compressive modulus, and morphology were examined. The results showed that these behaviors could be tunable via the control of MSF content. When the MSF content was 0.1%, the hydrogel had the compressive modulus of 0.32±0.07MPa, which was in the range of that of articular cartilage. The in vitro cytotoxic evaluation and cell culture of the micro/nanocomposite hydrogels in combination with mouse articular chondrocytes were also investigated. The results demonstrated that the micro/nanocomposite hydrogels with TGF-β1 was biocompatible to mouse articular chondrocytes and could support cells attachment well, indicating their potential as tissue engineering scaffolds for cartilage repair., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Photocrosslinkable water-soluble maleilated chitosan and methacrylated poly (vinyl alcohol) were synthesized and therefore maleilated chitosan/methacrylated poly (vinyl alcohol) (MCS/MPVA) hydrogels were prepared under UV radiation. Series of properties of the hydrogels including rheological property, swelling behavior, morphology and mechanical test were investigated. The main results showed that the MCS/MPVA hydrogels had fast gel-forming rate (complete transformation to gel within 150s), improved compressive strength at 0.169±0.011MPa and rapid absorbent capacity. These behaviors could be tunable via the control of weight ratio of MCS to MPVA. The indirect cytotoxicity assessments demonstrated the photocrosslinked hydrogels was compatible to mouse fibroblasts (L929 cells), indicating their potential as tissue engineering scaffolds., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The periphery of hyperbranched polysaccharides has many end groups that can be functioned and used as sites to interact with their surroundings. A water-insoluble hyperbranched β-d-glucan, coded as TM3a, extracted from sclerotia of an edible fungus (Pleurotus tuber-regium), was fractionated and modified chemically to obtain carboxymethylated derivatives (CTM3a). The solution properties of the carboxymethylated polysaccharides were studied systematically in phosphate buffer saline at 37 °C. The results indicated that the carboxymethylated glucans still kept hyperbranched structure after carboxymethylation, and existed as a swollen sphere-like chain conformation. The introduction of carboxymethylated groups permitted the formation of hydrogels through crosslinking CTM3a and silk fibroin with carbodiimide chemistry. The resultant hydrogels with porous and interconnected structure displayed good mechanical and swelling properties. This work provides some valuable and fundamental information of the natural hyperbranched polysaccharide from mushroom for further application in biomedical devices and tissue engineering., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

[Display omitted] • Carboxylated polyvinyl alcohol nanocomposite hydrogels were fabricated by photopolymerization of PVAGMACOOH and nano-scale hydroxyapatite. • Carboxylated polyvinyl alcohol nanocomposite hydrogels exhibited excellent compressive strength and tensile strength. • The introduction of nano-scale hydroxyapatite significantly enhanced cytocompatibility and cell adhesion of the hydrogels. Polyvinyl alcohol (PVA) hydrogel is a kind of biomaterial with broad application prospects in the biomedical fields, but its poor mechanical properties and weak cell adhesion hinder its development. Herein, carboxylated PVA with acrylate groups (PVAGMACOOH) is synthesized, and consequently carboxylated PVA nanocomposite hydrogels are fabricated by UV-irradiating the mixture of PVAGMACOOH solution and nano-scale hydroxyapatite (HAP). The nanocomposite hydrogel can gel within several seconds under the UV light irradiation. Notably, it exhibits excellent compressive strength without fracture in the strain of more than 90%, while its tensile strength is 14.6 times of the pure PVA hydrogel without HAP, indicating energy dissipation mechanism by macromolecular chain creep and good load transferring from macromolecules to nanoparticles. Furthermore, the introduction of HAP significantly enhances cytocompatibility and cell adhesion of the hydrogel. The hydrogel would be a potential candidate for various biomedical applications. [ABSTRACT FROM AUTHOR]

Hydrogel adhesives integrating both rapid and strong adhesion to blooding tissues and biocompatibility are highly desired for fast hemostasis. Herein, a flexible hyaluronic acid hydrogel adhesive is fabricated via photocrosslinking of the solution originating from dopamine-conjugated maleic hyaluronic acid (DMHA) in situ. The introduction of acrylate groups with high substitutions into the hydrogel matrix endows the adhesive with rapid gelation and strong tissue adhesion properties through photopolymerization. Moreover, the high substitution of catechol groups with unoxidized state can not only induce red blood cell aggregation and platelets adhesion but also adhere to wound tissue to further enhance hemostasis. Based on its bio-adhesion and procoagulant activity, the DMHA hydrogel formed in situ reveals superior hemostatic performance in the rat liver injury model and noncompressible hemorrhage model, and rabbit femoral artery puncture model, compared to commercial products (gauze, absorbable gelatin sponge) and oxidized DMHA (SMHA) hydrogel. Besides, the hydrogel exhibited good adaptability, biodegradability, and superior cytocompatibility as well as negligible inflammation. This hydrogel adhesive is a promising biological adhesive for hemorrhage control. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Despite their potential in various biomedical applications, photocrosslinkable hyaluronate hydrogels have often been limited by weak formation and unsatisfied mechanical strength which can be attributed to insufficient substitution of photoactive groups on the hyaluronate backbone and the oxygen inhibition effect. In this study, a new approach for the production of hyaluronic acid (MHA) with high acrylate group substitution (i.e. 2.27) is developed. It is based on the reaction of sodium hyaluronate and maleic anhydride in dimethyl sulfoxide, which has never been reported previously. Furthermore, the thiol-acrylate photopolymerization approach is employed to prepare maleiated hyaluronic acid/thiol-terminated poly(ethylene glycol) (MHA/TPEG) hydrogels which can overcome the oxygen inhibition effect. And the hydrogels possess porous structures, high swelling ratio, and tunable degradation rate. Specifically, the hydrogels could gel quickly within 15 s and demonstrate improved stiff (G′ = 4100 Pa). The in vitro cytotoxic evaluation demonstrates that the hydrogels are cytocompatible to L929 cells. As a result, the in-situ formable hydrogel scaffolds exhibit great potential for medical applications. Highlights • Maleilated hyaluronic acid with high acrylate substitution was synthesized. • In-situ formable MHA/TPEG hydrogels were prepared by thiol-acrylate photopolymerization. • The hydrogels gelled quickly and were cytocompatible. [ABSTRACT FROM AUTHOR]

Photocrosslinkable hydrogels composed of natural materials exhibit great application potential in tissue engineering scaffolds. However, weak formation and poor mechanical property can usually be a limitation. Herein, the photo-clickable thiol-ene hydrogels based chitosan were synthesized using photopolymerization of maleic chitosan (MCS) and thiol-terminated poly (vinyl alcohol) (TPVA) in the presence of a biocompatible photoinitiator. Rheological property and absorbing behavior of the MCS/TPVA hydrogels could be tailored by varying the amount of TPVA in the feed. There was strong intermolecular hydrogen bonding between the molecules of MCS and TPVA. Notably, the MCS/TPVA hydrogel (MT-3) exhibited rapid gelation behavior (<120 s), improved stiff (G' = ∼5500 Pa) and compressive strength (0.285 ± 0.014 MPa), which were important for hydrogel scaffolds, especially for injectable hydrogel scaffolds. Photocrosslinked MCS/TPVA hydrogels was cytocompatible and could promote the L929 cells attachment and proliferation, showing their potential as tissue engineering scaffolds. [ABSTRACT FROM AUTHOR]

Self-healing hydrogels can repair their cracks, and restore their original properties. However, self-healing hydrogels usually face low mechanical strength and poor stability. By the dual crosslinking strategy, a self-healing hyaluronic acid-based hydrogel with enhanced strength was fabricated by dynamic acylhydrazone linkages between aldehyde-modified maleic sodium hyaluronate and 3,3′-dithiobis (propionylhydrazide) and subsequent photopolymerization among maleic groups in the hydrogel network. The hydrogels exhibit fast gelation and excellent self-healing capability due to the dynamic and reversible characteristics of acylhydrazone and disulfide linkages. Furthermore, the dual crosslinking increase the mechanical strength of the hydrogels and prolong their stabilization time. Swelling behaviors, morphology, and mechanical properties could be adjusted by altering the molar ratio of –NH–NH 2 /–CHO. Besides, the hydrogels displayed interesting pH-responsiveness and cytocompatibility. The hydrogels have potential applications in cell culture, drug delivery, and 3D bioprinting. [Display omitted] • Hyaluronate hydrogel was obtained by acylhydrazone linkages and photocrosslinking. • Excellent self-healing ability was acquired via dual reversible crosslinking. • Enhanced strength promoted hydrogel stabilization. • These hydrogels were pH-responsive and cytocompatible. [ABSTRACT FROM AUTHOR]

[Display omitted] • Multi-crosslinked Flexible CNC/PVAGMA/TA nanocomposite hydrogel fibers was prepared. • The CNC/PVAGMA/TA nanocomposite hydrogels exhibited excellent tensile strengths as well as high-water content of 70 %. • The hydrogel fibers can be easily knitted into various complex geometries or integral textiles. Hydrogel fibers with excellent mechanical properties are requested for biomedical applications, especially for flexible and wearable devices. However, it remains a challenge to fabricate hydrogel fibers with both enough strength and high water content. Herein, we prepare cellulose nanocrystal/polyvinyl alcohol nanocomposite hydrogels by rapid covalent crosslinking and the subsequent strong hydrogen bonding interaction derived from tannic acid. The multi-crosslinked skeletal structure endows the hydrogels with excellent tensile strengths as well as high water content, compared to the polyvinyl alcohol-glycidylmethacrylate hydrogels. Notably, P10C5T15 hydrogel can lift loads to 4.375 kg, which is approximately 2353 times its weight. Subsequently, the flexible and mechanically stable hydrogel fibers are fabricated with a tensile strength of 7.3 MPa and a breaking elongation of 123.8 %. Furthermore, the fabricated hydrogel fibers can be easily knitted into various complex geometries or integral textiles, suggesting their great potential for woven smart devices. [ABSTRACT FROM AUTHOR]

In this paper, we describe a simple and practical way to prepare hydrogel membranes in a conical channel (pipette tip). We used a pipette to create a gas pressure difference on both sides of the gel precursor, which drove the gel precursor to move in the pipette tip. During movement, the shape of the hydrogel precursor gradually becomes thinner as the radius of the tapered channel becomes larger. We use this principle to realize the highly controllable preparation of the hydrogel membrane structure (130 μm at its thinnest). Moreover, we fabricated a hydrogel membrane sensor in one step by implanting smart molecules in the hydrogel, which achieved rapid and sensitive detection of 0.5 μM–500 mM potassium ions. This method of preparing the hydrogel membrane sensor does not rely on professional membrane production equipment and complex molecular design processes, has high gel utilization and simple and controllable membrane thickness, and has a wide range of application value in the field of intelligent hydrogel-based analysis technology. • A simple and controllable microhydrogel membrane sensor preparation method. • Using gas pressure difference on both sides of the gel precursor to build an ultra-thin hydrogel membrane in a pipette tip. • The fluorescence signal of the gel membrane sensor was verified by a smartphone. • Rapid and sensitive detection of potassium ions was achieved with aptamer functionalized hydrogel. • This method realizes the micro quantification and high utilization of the hydrogel. [ABSTRACT FROM AUTHOR]

[Display omitted] • A double crosslinked approach was developed to prepare poly (vinyl alcohol) microcomposite hydrogels. • The MCC/PVAGMA/TA microcomposite hydrogel exhibited excellent tensile/compression strengths. • A prepared hydogel with the optimum composition can lift a weight that was ~2220 times of its weight. Polyvinyl alcohol (PVA) hydrogels, due to their excellent tissue viscoelasticity and biocompatibility, are widely used in biomedical fields e.g. tissue engineering. However, their poor mechanical properties greatly limit their applications, especially as load-bearing implants in the body. To address this issue, we first synthesize photocrosslinkable PVA-glycidyl methacrylate (PVAGMA) with the extremely low substitution degree (DS = 0.01) of methacryloyl groups, which can undergo chemical crosslinking to form a hydrogel network with good compression performance. Microcrystalline cellulose (MCC)/PVAGMA hydrogels are subsequently fabricated by photopolymerization approach followed by physical crosslinking with tannic acid (TA) as a cross-linking agent. By combing chemical and physical crosslinking, the double crosslinked PVA microcomposite hydrogels exhibit excellent tensile/compression strengths. Specifically, the hydrogels present 23-fold, 20-fold, and 25-fold increase in fracture stress, elastic modulus, and toughness respectively, compared to the pure PVAGMA hydrogels. Notably, a hydrogel with the optimum composition can lift a weight of 3.775 kg, which is about 2220 times of its own weight. Moreover, the hydrogels are cytocompatible at a relatively low extraction concentration, demonstrating their potential in biomaterials. [ABSTRACT FROM AUTHOR]