Hydrogel Tissue Research Articles

High Antimicrobial Electrotherapy and Wound Monitoring Hydrogel with Bimetal Phenolic Networks for Smart Healthcare

AbstractThe design and fabrication of novel soft bioelectronic materials for rapid wound healing and real‐time monitoring are critical for smart healthcare. However, developing such integrated multifunctional materials devices remains challenging due to fabrication dynamics and sensing interface issues. Herein, a novel strategy is presented for accelerating the kinetics of hydrogels integrating antimicrobial, electrotherapeutic, and wound monitoring functions via bimetallic phenolic networks. The Al3+ catalyzes the radical copolymerization reaction of acrylic acid, resulting in the gelation of the system within 10 s, and also catalyzes the redox reaction between silver and lignin, inducing the sustained release of catechol, which significantly enhances the hydrogel's antimicrobial activity and shortened the wound healing process. Meanwhile, the abundant non‐covalent interactions enhance the hydrogel's tissue adhesion, and mechanical properties (tensile strength 1.558 MPa and elongation 1563%). In addition, the bimetallic ions endow the hydrogels with excellent sensing properties. Under the synergy of electrical stimulation, the wound healing rate is accelerated. Notably, wound assessment can be performed by monitoring changes in electrical signals over the wound, which can assist physicians and patients in achieving intelligent wound management. This work provides new insights into the design and application of multifunctional smart bioelectronic materials.

An optical system for cellular mechanostimulation in 3D hydrogels

We introduce a method utilizing single laser-generated cavitation bubbles to stimulate cellular mechanotransduction in dermal fibroblasts embedded within 3D hydrogels. We demonstrate that fibroblasts embedded in either amorphous or fibrillar hydrogels engage in Ca2+ signaling following exposure to an impulsive mechanical stimulus provided by a single 250 µm diameter laser-generated cavitation bubble. We find that the spatial extent of the cellular signaling is larger for cells embedded within a fibrous collagen hydrogel as compared to those embedded within an amorphous polyvinyl alcohol polymer (SLO-PVA) hydrogel. Additionally, for fibroblasts embedded in collagen, we find an increased range of cellular mechanosensitivity for cells that are polarized relative to the radial axis as compared to the circumferential axis. By contrast, fibroblasts embedded within SLO-PVA did not display orientation-dependent mechanosensitivity. Fibroblasts embedded in hydrogels and cultured in calcium-free media did not show cavitation-induced mechanotransduction; implicating calcium signaling based on transmembrane Ca2+ transport. This study demonstrates the utility of single laser-generated cavitation bubbles to provide local non-invasive impulsive mechanical stimuli within 3D hydrogel tissue models with concurrent imaging using optical microscopy. Statement of significanceCurrently, there are limited methods for the non-invasive real-time assessment of cellular sensitivity to mechanical stimuli within 3D tissue scaffolds. We describe an original approach that utilizes a pulsed laser microbeam within a standard laser scanning microscope system to generate single cavitation bubbles to provide impulsive mechanostimulation to cells within 3D fibrillar and amorphous hydrogels. Using this technique, we measure the cellular mechanosensitivity of primary human dermal fibroblasts embedded in amorphous and fibrillar hydrogels, thereby providing a useful method to examine cellular mechanotransduction in 3D biomaterials. Moreover, the implementation of our method within a standard optical microscope makes it suitable for broad adoption by cellular mechanotransduction researchers and opens the possibility of high-throughput evaluation of biomaterials with respect to cellular mechanosignaling.

Functional-hydrogel-based electronic-skin patch for accelerated healing and monitoring of skin wounds

Conductive hydrogels feature reasonable electrical performance as well as tissue-like mechanical softness, thus positioning them as promising material candidates for soft bio-integrated electronics. Despite recent advances in materials and their processing technologies, however, facile patterning and monolithic integration of functional hydrogels (e.g., conductive, low-impedance, adhesive, and insulative hydrogels) for all-hydrogel-based soft bioelectronics still poses significant challenges. Here, we report material design, fabrication, and integration strategies for an electronic-skin (e-skin) patch based on functional hydrogels. The e-skin patch was fabricated by using photolithography-compatible functional hydrogels, such as poly(2-hydroxyethyl acrylate) (PHEA) hydrogel (substrate), Ag flake hydrogel (interconnection; conductivity: ∼571.43 S/cm), poly(3,4-ethylenedioxythiophene:polystyrene) (PEDOT:PSS) hydrogel (working electrode; impedance: ∼69.84 Ω @ 1 Hz), polydopamine (PDA) hydrogel (tissue adhesive; shear strength: ∼725.1 kPa), and poly(vinyl alcohol) (PVA) hydrogel (encapsulation). The properties of these functional hydrogels closely resemble those of human tissues in terms of water content and Young's modulus, enabling stable tissue-device interfacing in dynamically changing physiological environments. We demonstrated the efficacy of the e-skin patch through its application to accelerated healing and monitoring of skin wounds in mouse models − efficient fibroblast migration, proliferation, and differentiation promoted by electric field (EF) stimulation and iontophoretic drug delivery, and monitoring of the accelerated healing process through impedance mapping. The all-hydrogel-based e-skin patch is expected to create new opportunities for various clinically-relevant tissue interfacing applications.

Effect of orientation angle for needle-free jet injection

In this paper, we report on the delivery efficiency of needle-free jet injections using injectors with typical jet speed vj≈140m/s, orifice diameter do=157μm, and volume V=0.1 mL. The target substrates were either hydrogel tissue phantoms or porcine tissues combined with excised human skin. The novelty of this study is two-fold: First, we investigate the influence of injection angle relative to the skin surface, and second, we also study the influence of the jet path relative to the orientation of muscle fibers. While most commercial jet injectors employ a fitting that would render the device normal to the skin surface, recent studies have proposed oblique injections, which may be beneficial for intradermal or subcutaneous tissue injection. Furthermore, for deeper intramuscular injections, we propose that an angled jet path taking the muscle fiber orientation into account may result in a bolus or dispersion zone that is conducive to increased cellular uptake of the drug.

PVA Hydrogels Supplemented with PLA Mesh for Tissue Regeneration Scaffold.

This study examined the tensile strength and biocompatibility properties of polyvinyl alcohol (PVA) hydrogel tissue regeneration scaffolds with polylactic acid (PLA) mesh fabric added as reinforcement, with a focus on the impact of heat treatment temperature and the number of layers of the PLA mesh fabric. The hydrogel scaffolds were prepared using a freeze-thaw method to create PVA hydrogel, with the PLA mesh fabric placed inside the hydrogel. The swelling ratio of the PVA/PLA hydrogel scaffolds decreased with increasing layer number and heat treatment temperature of the PLA mesh. The gel strength was highest when five layers of PLA mesh fabric were added, heat-treated at 120 °C, and confirmed to be properly placed inside the hydrogel by SEM images. The MTT assay and DAPI staining using HaCaT cells demonstrated that the cell proliferation was uninterrupted throughout the experimental period, confirming the biocompatibility of the scaffold. Therefore, we confirmed the possibility of using PLA mesh fabric as a reinforcement for PVA hydrogel to improve the strength of scaffolds for tissue regeneration, and we confirmed the potential of PLA mesh fabric as a reinforcement for various biomaterials.

Tough and Biocompatible Hydrogel Tissue Adhesives Entirely Based on Naturally Derived Ingredients

Tough and Biocompatible Hydrogel Tissue Adhesives Entirely Based on Naturally Derived Ingredients

Hydrogel Tissue Bioengineered Scaffolds in Bone Repair: A Review.

Large bone defects due to trauma, infections, and tumors are difficult to heal spontaneously by the body's repair mechanisms and have become a major hindrance to people's daily lives and economic development. However, autologous and allogeneic bone grafts, with their lack of donors, more invasive surgery, immune rejection, and potential viral transmission, hinder the development of bone repair. Hydrogel tissue bioengineered scaffolds have gained widespread attention in the field of bone repair due to their good biocompatibility and three-dimensional network structure that facilitates cell adhesion and proliferation. In addition, loading natural products with nanoparticles and incorporating them into hydrogel tissue bioengineered scaffolds is one of the most effective strategies to promote bone repair due to the good bioactivity and limitations of natural products. Therefore, this paper presents a brief review of the application of hydrogels with different gel-forming properties, hydrogels with different matrices, and nanoparticle-loaded natural products loaded and incorporated into hydrogels for bone defect repair in recent years.

All Biodisintegratable Hydrogel Biohybrid Neural Interfaces with Synergistic Performances of Microelectrode Array Technologies, Tissue Scaffolding, and Cell Therapy

AbstractBiohybrid neural interfaces (BHNIs) are a new class of neuromodulating devices that integrate neural microelectrode arrays (MEAs) and cell transplantation to improve treatment of nerve injuries and disorders. However, current BHNI devices are made from abiotic materials that are usually bio‐passive, non‐biodisintegratable, or rigid, which restricts encapsulated cell activity and host nerve reconstruction and frequently leads to local tissue inflammation. Herein, the first MEA composed of all disintegratable hydrogel tissue scaffold materials with synergistic performances of tissue conformal adhesiveness, MEA technologies, tissue scaffolding and stem cell therapy on a time scale appropriate for nerve tissue repair is proposed. In particular, the MEA conductive tracks are made from extracellular matrix (ECM)‐based double‐cross‐linked dual‐electrically conductive hydrogel (ECH) systems with robust tissue‐mimicking chemical/physical properties, electrical conductivity, and an affinity for neural progenitor stem cells. Meanwhile, the MEA hydrogel substrate prepared from transglutaminase‐incorporated gelatin/silk precursors simultaneously promotes gelation and interfacial adhesion between all MEA stacks, leading to rapid and scalable device integration. When the full hydrogel MEA is subjected to various mechanical stimuli and moisture, it is structurally stable with a low impedance (4 ± 3 kΩ) comparable to a recently reported benchmark. With seamless lamination around peripheral nerve fibers, the device permits successive neural signal monitoring for wound condition evaluation, while demonstrating synergistic effects of spatiotemporally controlled electrical stimulation and cell transplantation to accelerate restoration of motor function. This BHNI is completely degraded by 1 month thus eliminating the need for surgical retrieval to stably remain, interact, and further fuse with host tissues, successfully exhibiting compatible integration of biology and an implanted electrical system.

Hydrogels with brain tissue-like mechanical properties in complex environments

In surgical training and experimental research, brain tissues immersed in cerebrospinal fluid often exhibit complex deformation and strain rate effects that can compromise their reliability and stability. Therefore, it is essential to develop a high-fidelity human brain tissue simulant material that serves as a physical surrogate model to understand its mechanical behavior, such as traumatic brain injury (TBI). However, the existing simulant materials have failed to meet the required mechanical properties. This study presents a composite hydrogel consisting of both a rigid polysaccharides network (Sodium alginate and Pectin) and a flexible polyacrylamide network, exhibiting brain tissue-like mechanical properties under various solution environments and strain rates. The results show that nonlinear mechanical behavior and good similarity under various external environments (artificial cerebrospinal fluid, normal saline, deionized water, and air environments) and different strain rates (0.001 s−1,900 s−1,1700 s−1). By analyzing the experimental data and theoretical analysis, we examine the effects of complex environments on the mechanical behavior of composite hydrogel and porcine brain tissue. Given that the properties of human brain tissue resemble those of porcine brain tissue, our work has significant reference value in realizing surgical training and advancing related research in biomedical engineering.

The marriage of immunomodulatory, angiogenic, and osteogenic capabilities in a piezoelectric hydrogel tissue engineering scaffold for military medicine

BackgroundMost bone-related injuries to grassroots troops are caused by training or accidental injuries. To establish preventive measures to reduce all kinds of trauma and improve the combat effectiveness of grassroots troops, it is imperative to develop new strategies and scaffolds to promote bone regeneration.MethodsIn this study, a porous piezoelectric hydrogel bone scaffold was fabricated by incorporating polydopamine (PDA)-modified ceramic hydroxyapatite (PDA-hydroxyapatite, PHA) and PDA-modified barium titanate (PDA-BaTiO3, PBT) nanoparticles into a chitosan/gelatin (Cs/Gel) matrix. The physical and chemical properties of the Cs/Gel/PHA scaffold with 0–10 wt% PBT were analyzed. Cell and animal experiments were performed to characterize the immunomodulatory, angiogenic, and osteogenic capabilities of the piezoelectric hydrogel scaffold in vitro and in vivo.ResultsThe incorporation of BaTiO3 into the scaffold improved its mechanical properties and increased self-generated electricity. Due to their endogenous piezoelectric stimulation and bioactive constituents, the as-prepared Cs/Gel/PHA/PBT hydrogels exhibited cytocompatibility as well as immunomodulatory, angiogenic, and osteogenic capabilities; they not only effectively induced macrophage polarization to M2 phenotype but also promoted the migration, tube formation, and angiogenic differentiation of human umbilical vein endothelial cells (HUVECs) and facilitated the migration, osteo-differentiation, and extracellular matrix (ECM) mineralization of MC3T3-E1 cells. The in vivo evaluations showed that these piezoelectric hydrogels with versatile capabilities significantly facilitated new bone formation in a rat large-sized cranial injury model. The underlying molecular mechanism can be partly attributed to the immunomodulation of the Cs/Gel/PHA/PBT hydrogels as shown via transcriptome sequencing analysis, and the PI3K/Akt signaling axis plays an important role in regulating macrophage M2 polarization.ConclusionThe piezoelectric Cs/Gel/PHA/PBT hydrogels developed here with favorable immunomodulation, angiogenesis, and osteogenesis functions may be used as a substitute in periosteum injuries, thereby offering the novel strategy of applying piezoelectric stimulation in bone tissue engineering for the enhancement of combat effectiveness in grassroots troops.

A Modified Constitutive Model for Isotropic Hyperelastic Polymeric Materials and Its Parameter Identification.

Given the importance of hyperelastic constitutive models in the design of engineering components, researchers have been developing the improved and new constitutive models in search of a more accurate and even universal performance. Here, a modified hyperelastic constitutive model based on the Yeoh model is proposed to improve its prediction performance for multiaxial deformation of hyperelastic polymeric materials while retaining the advantages of the original Yeoh model. The modified constitutive model has one more correction term than the original model. The specific form of the correction term is a composite function based on a power function represented by the principal stretches, which is derived from the corresponding residual strain energy when the Yeoh model predicts the equibiaxial mode of deformation. In addition, a parameter identification method based on the cyclic genetic-pattern search algorithm is introduced to accurately obtain the parameters of the constitutive model. By applying the modified model to the experimental datasets of various rubber or rubber-like materials (including natural unfilled or filled rubber, silicone rubber, extremely soft hydrogel and human brain cortex tissue), it is confirmed that the modified model not only possesses a significantly improved ability to predict multiaxial deformation, but also has a wider range of material applicability. Meanwhile, the advantages of the modified model over most existing models in the literatures are also demonstrated. For example, when characterizing human brain tissue, which is difficult for most existing models in the literature, the modified model has comparable predictive accuracy with the third-order Ogden model, while maintaining convexity in the corresponding deformation domain. Moreover, the effective prediction ability of the modified model for untested equi-biaxial deformation of different materials has also been confirmed using only the data of uniaxial tension and pure shear from various datasets. The effective prediction for the untested equibiaxial deformation makes it more suitable for the practice situation where the equibiaxial deformation of certain polymeric materials is unavailable. Finally, compared with other parameter identification methods, the introduced parameter identification method significantly improves the predicted accuracy of the constitutive models; meanwhile, the uniform convergence of introduced parameter identification method is also better.

Three-dimensional printed hydrogel model vs cadaver: comparing inflatable penile prosthesis training and evaluation.

Penile prosthesis implantation offers a durable, safe, and effective treatment option for male erectile dysfunction; however, many urologists feel apprehensive and uncomfortable placing penile prostheses due to limited training, low surgical experience, and intra- and postoperative complication management. To compare a previously validated hydrogel inflatable penile prosthesis (IPP) training model with cadaver simulations across 4 main categories: anatomic replication and realism, procedural replication and realism, educational effectiveness, and efficacy and safety. An overall 88 participants (15 attendings, 18 fellows, and 55 residents) performed guided IPP placements on a cadaver and a hydrogel model. Based on a 5-point Likert scale, postsurveys were used to assess the participants' opinions regarding anatomic replication and realism, procedural replication and realism, educational effectiveness, and safety between the hydrogel model and cadavers. A direct head-to-head scenario was created, allowing participants to fully utilize the hydrogel model and cadaver, which ensured the most accurate comparison possible. A total of 84% agreed that the hydrogel model replicates the relevant human cadaveric anatomy for the procedure, whereas 69% agreed that the hydrogel tissue resembles the appearance of cadaveric tissue. Regarding the pubic bone, outer skin, corporal bodies, dartos layer, and scrotum, 79%, 74%, 82%, 46%, and 30% respectively agreed that the hydrogel tissue resembled the texture/behavior of cadavers. Furthermore, 66% of participants agreed that the hydrogel model replicates all the procedural steps. Specifically, participants agreed that the model replicates the skin incision/dartos dissection (74%), placement of stay suture and corporotomy (92%), corporal dilation (81%), measurement of prosthetic size (98%), reservoir placement (43%), IPP placement (91%), scrotal pump placement (48%), and skin closure (51%). Finally, 86%, 93%, and 78% agreed that the hydrogel model is useful for improving technical skills, as a teaching/practicing tool, and as an evaluation tool, respectively. To conclude, 81% of participants stated that they would include the hydrogel model platform in their current training. By replicating the IPP procedure, the hydrogel model offers an additional high-fidelity training opportunity for urologists, allowing them to improve their skills and confidence in placing penile prostheses, with the goal of improving patient surgical outcomes. The hydrogel training model allows users to perform the entire IPP placement procedure with high anatomic realism and educational effectiveness, maintaining many of the high-fidelity benefits seen in cadavers while improving safety and accessibility. Ultimately, this high-fidelity nonbiohazardous training model can be used to supplement and bolster current IPP training curriculums.

High-frequency irreversible electroporation improves survival and immune cell infiltration in rodents with malignant gliomas.

Irreversible electroporation (IRE) has been previously investigated in preclinical trials as a treatment for intracranial malignancies. Here, we investigate next generation high-frequency irreversible electroporation (H-FIRE), as both a monotherapy and a combinatorial therapy, for the treatment of malignant gliomas. Hydrogel tissue scaffolds and numerical modeling were used to inform in-vivo H-FIRE pulsing parameters for our orthotopic tumor-bearing glioma model. Fischer rats were separated into five treatment cohorts including high-dose H-FIRE (1750V/cm), low-dose H-FIRE (600V/cm), combinatorial high-dose H-FIRE + liposomal doxorubicin, low-dose H-FIRE + liposomal doxorubicin, and standalone liposomal doxorubicin groups. Cohorts were compared against a standalone tumor-bearing sham group which received no therapeutic intervention. To further enhance the translational value of our work, we characterize the local and systemic immune responses to intracranial H-FIRE at the study timepoint. The median survival for each cohort are as follows: 31 days (high-dose H-FIRE), 38 days (low-dose H-FIRE), 37.5 days (high-dose H-FIRE + liposomal doxorubicin), 27 days (low-dose H-FIRE + liposomal doxorubicin), 20 days (liposomal doxorubicin), and 26 days (sham). A statistically greater overall survival fraction was noted in the high-dose H-FIRE + liposomal doxorubicin (50%, p = 0.044), high-dose H-FIRE (28.6%, p = 0.034), and the low-dose H-FIRE (20%, p = 0.0214) compared to the sham control (0%). Compared to sham controls, brain sections of rats treated with H-FIRE demonstrated significant increases in IHC scores for CD3+ T-cells (p = 0.0014), CD79a+ B-cells (p = 0.01), IBA-1+ dendritic cells/microglia (p = 0.04), CD8+ cytotoxic T-cells (p = 0.0004), and CD86+ M1 macrophages (p = 0.01). H-FIRE may be used as both a monotherapy and a combinatorial therapy to improve survival in the treatment of malignant gliomas while also promoting the presence of infiltrative immune cells.

Imageable AuNP-ECM Hydrogel Tissue Implants for Regenerative Medicine.

In myocardial infarction, a blockage in one of the coronary arteries leads to ischemic conditions in the left ventricle of the myocardium and, therefore, to significant death of contractile cardiac cells. This process leads to the formation of scar tissue, which reduces heart functionality. Cardiac tissue engineering is an interdisciplinary technology that treats the injured myocardium and improves its functionality. However, in many cases, mainly when employing injectable hydrogels, the treatment may be partial because it does not fully cover the diseased area and, therefore, may not be effective and even cause conduction disorders. Here, we report a hybrid nanocomposite material composed of gold nanoparticles and an extracellular matrix-based hydrogel. Such a hybrid hydrogel could support cardiac cell growth and promote cardiac tissue assembly. After injection of the hybrid material into the diseased area of the heart, it could be efficiently imaged by magnetic resonance imaging (MRI). Furthermore, as the scar tissue could also be detected by MRI, a distinction between the diseased area and the treatment could be made, providing information about the ability of the hydrogel to cover the scar. We envision that such a nanocomposite hydrogel may improve the accuracy of tissue engineering treatment.

Development of a three-dimensional in vitro blood-brain barrier using the chitosan-alginate polyelectrolyte complex as the extracellular matrix

Polyelectrolyte complexes (PECs) consist of a spontaneous assembly of oppositely charged polysaccharides. PECs can be used to obtain a hydrogel tissue scaffold in tissue culture. In this study, it is aimed to use PEC as a blood-brain barrier (BBB) model scaffold. By mixing polycationic chitosan and polyanionic alginate solutions at a certain ratio it was obtained a 3D hydrogel scaffold and mimicked in vivo environment of the tissue. The PEC hydrogel scaffold’s chemical, physical, and mechanical characterizations were performed with FTIR, DSC, DMA, and Micro-CT analyses. In order to develop an in vitro BBB model, the human neuroblastoma cell line (SH-SY5Y) and mouse astrocyte cell line (C8-D1A) were mixed into a hydrogel, which is the abluminal side of the BBB. Human microvascular endothelial cells (HBEC-5i) were seeded on the hydrogel, and it was aimed to mimic the luminal side of the BBB. The characterization of the BBB model was determined by measuring the TEER, observation of the cell morphology with SEM, performing the permeability of Lucifer Yellow, and observation of tight junction proteins with immunofluorescence staining. As a result, HBEC-5i cells expressed tight junction proteins (ZO-1 and Claudin-5), showed TEER of 340 ± 22 Ω.cm2, and the Lucifer Yellow permeability of 7.4 × 10−7 ± 2.7 × 10−7 cm/s, which was suitable for use as an in vitro BBB model. Using a hydrogel PEC composed of chitosan and alginate as an extracellular matrix increased the direct interaction of endothelial cells, astrocytes, and neurons with each other and thus obtained a much less permeable model compared to other standard transwell models. Graphical abstract [Formula: see text]

Engineering Tridimensional Hydrogel Tissue and Organ Phantoms with Tunable Springiness

AbstractBiomimicking organ phantoms with vivid biological structures and soft and slippery features are essential for in vitro biomedical applications yet remain hither to unmet challenges in their fabrication such as balancing between spatial structural complexity and matchable mechanical properties. Herein, 3D printable tissue‐mimicking elastomeric double network hydrogels with tailorable stiffness are evolved to idiosyncratically match diverse biological soft tissues by regulating the compositions of hydrogel matrix and the density of metal coordination bonds. Relying on digital light processing 3D printing, various mechanically tunable biomimetic volumetric hydrogel organ constructs with structural complexity and fidelity, including kidney, brain, heart, liver, stomach, lung, trachea, intestine, and even the intricate vascularized tissues, are fabricated faultlessly. Proof‐of‐concept 3D printed hydrogel heart and liver phantoms provide sophisticated internal channels and cavity structures and external realistic anatomical architectures that more closely mimic native organs. For the in vitro application demonstration, a 3D printed hydrogel brain phantom with tortuous cerebral arteries and slippery characters serves as an effective neurosurgical training platform for realistic simulation of endovascular interventions. This platform offers a means to construct mechanically precisely tunable hydrogel‐based biomimetic organ phantoms that are expected to be used in surgical training, medical device testing, and organs‐on‐chips.

Preparation and Characterization of Extracellular Matrix Hydrogels Derived from Acellular Cartilage Tissue.

Decellularized matrices can effectively reduce severe immune rejection with their cells and eliminated nucleic acid material and provide specific environments for tissue repair or tissue regeneration. In this study, we prepared acellular cartilage matrix (ACM) powder through the decellularization method and developed ACM hydrogels by physical, chemical, and enzymatic digestion methods. The results demonstrated that the small size group of ACM hydrogels exhibited better gel conditions when the concentration of ACM hydrogels was 30 and 20 mg/mL in 1N HCl through parameter adjustment. The data also confirmed that the ACM hydrogels retained the main components of cartilage: 61.18% of glycosaminoglycan (GAG) and 78.29% of collagen, with 99.61% of its DNA removed compared to samples without the decellularization procedure (set as 100%). Through turbidimetric gelation kinetics, hydrogel rheological property analysis, and hydrogel tissue physical property testing, this study also revealed that increasing hydrogel concentration is helpful for gelation. Besides, the ex vivo test confirmed that a higher concentration of ACM hydrogels had good adhesive properties and could fill in cartilage defects adequately. This study offers useful information for developing and manufacturing ACM hydrogels to serve as potential alternative scaffolds for future cartilage defect treatment.

The CaT stretcher: An open-source system for delivering uniaxial strain to cells and tissues (CaT).

Integration of mechanical cues in conventional 2D or 3D cell culture platforms is an important consideration for in vivo and ex vivo models of lung health and disease. Available commercial and published custom-made devices are frequently limited in breadth of applications, scalability, and customization. Herein we present a technical report on an open-source, cell and tissue (CaT) stretcher, with modularity for different in vitro and ex vivo systems, that includes the following features: 1) Programmability for modeling different breathing patterns, 2) scalability to support low to high-throughput experimentation, and 3) modularity for submerged cell culture, organ-on-chips, hydrogels, and live tissues. The strategy for connecting the experimental cell or tissue samples to the stretching device were designed to ensure that traditional biomedical outcome measurements including, but not limited to microscopy, soluble mediator measurement, and gene and protein expression remained possible. Lastly, to increase the uptake of the device within the community, the system was built with economically feasible and available components. To accommodate diverse in vitro and ex vivo model systems we developed a variety of chips made of compliant polydimethylsiloxane (PDMS) and optimized coating strategies to increase cell adherence and viability during stretch. The CaT stretcher was validated for studying mechanotransduction pathways in lung cells and tissues, with an increase in alpha smooth muscle actin protein following stretch for 24h observed in independent submerged monolayer, 3D hydrogel, and live lung tissue experiments. We anticipate that the open-source CaT stretcher design will increase accessibility to studies of the dynamic lung microenvironment through direct implementation by other research groups or custom iterations on our designs.

Supratough and stretchable hydrogels with time-space controllability for athletic rehabilitation

There is a higher risk of injury for athletes when the intensive competition occurs. Minimally invasive surgery is still the first choice for athletes because of its small wound surface and fast recovery. In addition, knowing whether athletes recover in real time at the first time is beneficial for the athletes to return to the competition as soon as possible and maintain their peak performance. We developed a medical hydrogel to meet the dual needs of minimally invasive therapy and wearable testing. A novel ε-PL/PVP/MXene (εPM) hydrogel with spatio-temporal control and in situ enhancement was prepared by the concept of microchemical reaction cavity. MXene was introduced as the microchemical reaction center, and the dual effects of heat transport and microcatalysis were utilized to make the gel network uniform and moldability after injection in vivo, so as to realize the filling and treatment of irregular wounds. The hydrogel tissue is not only adhesive, self-healing and soft, but also super tough, keeping its shape stable under repeated stretches, intense hammering, continuous trampling, and even the extremely catastrophic impact of being run over 50 times by a car. At the same time, the hydrogel has excellent ionic conductivity (4.12 S/m) and sensing ability, which can record athletes' movement characteristics in real time and transmit them to doctors through wireless Bluetooth, so as to make accurate judgment on the recovery of health. This is the first exploration of the combination of hydrogel in the field of minimally invasive therapy and wearable devices, which opens up a new avenue for efficient minimally invasive therapy and accurate rehabilitation monitoring.

Study on the 3D BioPrinting Technology of Hydrogel Tissue Engineering scaffolds

The precision molding capability of bio-3D printing is the basis for its application in tissue engineering, and SA-Gel two-component hydrogel has been widely used in bio-3D printing manufacturing of tissue engineering scaffolds. The extrusionability of hydrogel is the key point for the printing precision. In this paper, starting from the concentration, ratio, rheology and cross-linking mode of hydrogel, the research ideas of “single factor independent analysis” and multi-factor comprehensive application are adopted to solve the printing accuracy. Through the research and screening of printing parameters and printing compensation technology, the accurate printing of the 1D line segment and 2D grid structure at 45°C for SA-Gel hydrogel with 2% and 8% mass respectively have been achieved.