Hydrocolloid-based nutraceutical delivery systems: Potential of κ-carrageenan hydrogel beads for sustained release of curcumin.

This study investigates the potential of κ-carrageenan hydrogel beads as a delivery system for curcumin, a bioactive compound with various health benefits. Hydrogel beads were prepared using the extrusion technique with a hypodermic needle. The encapsulation efficiency of curcumin in the κ-carrageenan hydrogel beads was found to be 74.61 ± 3.2 %. FTIR spectroscopy analysis revealed shifts in absorption peaks, indicating possible hydrogen bonding and/or ionic interactions between the polymer and salt. An increase in the melting point of curcumin, by 25 °C, in curcumin- κ-carrageenan beads suggests the heat protection offered by the carrageenan chains to curcumin molecules. The in vitro release of curcumin from the beads suggests a sustained and pH-dependent release nature. The release kinetics follow the first order and the Korsmeyer-Peppas model. The outcome offers value-added delivery systems of bioactive compounds toward developing novel food and pharmaceutical applications.

A Novel Approach to Orthotopic Hepatocyte Transplantation Engineered With Liver Hydrogel for Fibrotic Livers, Enhancing Cell-Cell Interaction and Angiogenesis.

Hepatocyte transplantation (HCT) is a potential bridging therapy or an alternative to liver transplantation. Conventionally, single-cell hepatocytes are injected via the portal vein. This strategy, however, has yet to overcome poor cell engraftment and function. Therefore, we developed an orthotopic HCT method using a liver-derived extracellular matrix (L-ECM) gel. PXB cells (flesh mature human hepatocytes) were dispersed into the hydrogel solution in vitro, and the gel solution was immediately gelated in 37°C incubators to investigate the affinity between mature human hepatocyte and the L-ECM gel. During the 3-day cultivation in hepatocyte medium, PXB cells formed cell aggregates via cell-cell interactions. Quantitative analysis revealed human albumin production in culture supernatants. For the in vivo assay, PXB cells were encapsulated in the L-ECM gel and transplanted between the liver lobes of normal rats. Pathologically, the L-ECM gel was localized at the transplant site and retained PXB cells. Cell survival and hepatic function marker expression were verified in another rat model wherein thioacetamide was administered to induce liver fibrosis. Moreover, cell-cell interactions and angiogenesis were enhanced in the L-ECM gel compared with that in the collagen gel. Our results indicate that L-ECM gels can help engraft transplanted hepatocytes and express hepatic function as a scaffold for cell transplantation.

Constructing gellan gum/konjac glucomannan/wheat fiber composite hydrogel to simulate edible cartilage by ionic cross-link and moisture regulation.

The utilization of non-animal-derived materials to imitate cartilage is critical for the advancement of plant-based simulated meat. In this study, gellan gum (GG), konjac glucomannan (KGM), and wheat fiber (WF) were used to construct hydrogel, and the mechanical strength, water properties, and microstructure were regulated by constructing Ca2+ cross-links and moisture control. The hardness, chewiness, resilience, shear force, and shear energy of the Ca2+ cross-linked samples were significantly improved. Extrusion dehydration further changes the related mechanical properties of the hydrogel and results in a tighter microstructure. The findings suggest that the establishment of Ca2+ cross-links and water regulation are efficacious techniques for modifying the texture of the GG/KGM/WF composite hydrogel. Correlation analysis and sensory evaluation showed that the test indexes and sensory scores of the samples with Ca2+ crosslinking and 80 % moisture content were similar to chicken breast cartilage, and the samples with Ca2+ crosslinking and 70 % moisture content were similar to pig crescent bone. This study presents a framework for designing edible cartilage simulators using polysaccharide hydrogels, with implications for enhancing the resemblance of plant-based meat products to real meat and expanding the range of vegetarian offerings available.

Konjac glucomannan-fibrin composite hydrogel as a model for ideal scaffolds for cell-culture meat.

In this study, composite gel was prepared from konjac glucomannan (KGM) and fibrin (FN). Composite gels with different concentration ratios were compared in terms of their mechanical properties, rheological properties, water retention, degradation rate, microstructure and biocompatibility. The results showed that the composite gels had better gel strength and other properties than non-composite gels. In particular, composite hydrogels with low Young's modulus formed when the KGM concentration was 0.8% and the FN concentration was 1.2%. The two components were cross linked through hydrogen-bond interaction, which formed a more stable gel structure with excellent water retention and in-vitro degradation rates, which were conducive to myogenic differentiation of ectomesenchymal stem cells (EMSCs). KGM-FN composite gel was applied to the preparation of cell-culture meat, which had similar texture properties and main nutrients to animal meat as well as higher content of dry base protein and dry base carbohydrate.

Enhancing storage and gastroprotective viability of Lactiplantibacillus plantarum encapsulated by sodium caseinate-inulin-soy protein isolates composites carried within carboxymethyl cellulose hydrogel.

Probiotics are subjected to various edible coatings, especially proteins and polysaccharides, which serve as the predominant wall materials, with ultrasound, a sustainable green technology. Herein, sodium caseinate, inulin, and soy protein isolate composites were produced using multi-frequency ultrasound and utilized to encapsulateLactiplantibacillus plantarumto enhance its storage, thermal, and gastrointestinal viability. The physicochemical analyses revealed that the composites with 5 % soy protein isolate treated with ultrasound at 50 kHz exhibited enough repulsion forces to maintain stability, pH resistance, and the ability to encapsulate larger particles and possessed the highest encapsulation efficiency (95.95 %). The structural analyses showed changes in the composite structure at CC, CH, CO, and amino acid residual levels. Rheology, texture, and water-holding capacity demonstrated the production of soft hydrogels with mild chewing and gummy properties, carried the microcapsules without coagulation or sedimentation. Moreover, the viability attributes ofL. plantarumevinced superior encapsulation, protecting them for at least eight weeks and against heat (63 °C), reactive oxidative species (H2O2), and GI conditions.

Carboxymethyl cellulose-based rotigotine nanocrystals-loaded hydrogel for increased transdermal delivery with alleviated skin irritation.

Transdermal rotigotine (RTG) therapy is prescribed to manage Parkinson's disease (Neupro® patch). However, its use is suffered from application site reactions. Herein, drug nanocrystalline suspension (NS)-loaded hydrogel (NS-HG) employing polysaccharides simultaneously as suspending agent and hydrogel matrix was constructed for transdermal delivery, with alleviated skin irritation. RTG-loaded NS-HG was prepared using a bead-milling technique, employing sodium carboxylmethyl cellulose (Na.CMC) as nano-suspending agent (molecular weight 90,000 g/mol) and hydrogel matrix (700,000 g/mol), respectively. NS-HG was embodied as follows: drug loading: ≤100 mg/mL; shape: rectangular crystalline; crystal size: <286.7 nm; zeta potential: -61 mV; viscosity: <2.16 Pa·s; and dissolution rate: >90 % within 15 min. Nuclear magnetic resonance analysis revealed that the anionic polymers bind to RTG nanocrystals via charge interaction, affording uniform dispersion in the matrix. Rodent transdermal absorption of RTG from NS-HG was comparable to that from microemulsions, and proportional to drug loading. Moreover, NS-HG was skin-friendly; erythema and epidermal swelling were absent after repeated application. Further, NS-HG was chemically stable; >95 % of the drug was preserved up to 4 weeks under long term (25 °C/RH60%), accelerated (40 °C/RH75%), and stress (50 °C) storage conditions. Therefore, this novel cellulose derivative-based nanoformulation presents a promising approach for effective transdermal RTG delivery with improved tolerability.

Cell-adhesive double network self-healing hydrogel capable of cell and drug encapsulation: New platform to construct biomimetic environment with bottom-up approach.

This study presents the development and characterization of a novel double-network self-healing hydrogel based on N-carboxyethyl chitosan (CEC) and oxidized dextran (OD) with the incorporation of crosslinked collagen (CEC-OD/COL-GP) to enhance its biological and physicochemical properties. The hydrogel formed via dynamic imine bond formation exhibited efficient self-healing within 30 min, and a compressive modulus recovery of 92 % within 2 h. In addition to its self-healing ability, CEC-OD/COL-GP possesses unique physicochemical characteristics including transparency, injectability, and adhesiveness to various substrates and tissues. Cell encapsulation studies confirmed the biocompatibility and suitability of the hydrogel as a cell-culture scaffold, with the presence of a collagen network that enhances cell adhesion, spreading, long-term cell viability, and proliferation. Leveraging their unique properties, we engineered assemblies of self-healing hydrogel modules for controlled spatiotemporal drug delivery and constructed co-culture models that simulate angiogenesis in tumor microenvironments. Overall, the CEC-OD/COL-GP hydrogel is a versatile and promising material for biomedical applications, offering a bottom-up approach for constructing complex structures with self-healing capabilities, controlled drug release, and support for diverse cell types in 3D environments. This hydrogel platform has considerable potential for advancements in tissue engineering and therapeutic interventions.

Schiff base crosslinked hyaluronic acid hydrogels with tunable and cell instructive time-dependent mechanical properties.

The dynamic interplay between cells and their native extracellular matrix (ECM) influences cellular behavior, imposing a challenge in biomaterial design. Dynamic covalent hydrogels are viscoelastic and show self-healing ability, making them a potential scaffold for recapitulating native ECM properties. We aimed to implement kinetically and thermodynamically distinct crosslinkers to prepare self-healing dynamic hydrogels to explore the arising properties and their effects on cellular behavior. To do so, aldehyde-substituted hyaluronic acid (HA) was synthesized to generate imine, hydrazone, and oxime crosslinked dynamic covalent hydrogels. Differences in equilibrium constants of these bonds yielded distinct properties including stiffness, stress relaxation, and self-healing ability. The effects of degree of substitution (DS), polymer concentration, crosslinker to aldehyde ratio, and crosslinker functionality on hydrogel properties were evaluated. The self-healing ability of hydrogels was investigated on samples of the same and different crosslinkers and DS to obtain hydrogels with gradient properties. Subsequently, human dermal fibroblasts were cultured in 2D and 3D to assess the cellular response considering the dynamic properties of the hydrogels. Moreover, assessing cell spreading and morphology on hydrogels having similar modulus but different stress relaxation rates showed the effects of matrix viscoelasticity with higher cell spreading in slower relaxing hydrogels.

Synthesis and real-time characterization of self-healing, injectable, fast-gelling hydrogels based on alginate multi-reducing end polysaccharides (MREPs).

Polysaccharide-based hydrogels are promising for many biomedical applications including drug delivery, wound healing, and tissue engineering. We illustrate herein self-healing, injectable, fast-gelling hydrogels prepared from multi-reducing end polysaccharides, recently introduced by the Edgar group. Simple condensation of reducing ends from multi-reducing end alginate (M-Alg) with amines from polyethylene imine (PEI) in water affords a dynamic, hydrophilic polysaccharide network. Trace amounts of acetic acid can accelerate the gelation time from hours to seconds. The fast-gelation behavior is driven by rapid Schiff base formation and strong ionic interactions induced by acetic acid. A cantilever rheometer enables real-time monitoring of changes in viscoelastic properties during hydrogel formation. The reversible nature of these crosslinks (imine bonds, ionic interactions) provides a hydrogel with low toxicity in cell studies as well as self-healing and injectable properties. Therefore, the self-healing, injectable, and fast-gelling M-Alg/PEI hydrogel holds substantial promise for biomedical, agricultural, controlled release, and other applications.

Rapid prototyping and facile customization of conductive hydrogel bioelectronics based on all laser process.

Proper customization in size and shape is essential in implantable bioelectronics for stable bio-signal recording. Over the past decades, many researchers have heavily relied on conventional photolithography processes to fabricate implantable bioelectronics. Therefore, they could not avoid the critical limitation of high cost and complex processing steps to optimize bioelectronic devices for target organs with various sizes and shapes. Here, we propose rapid prototyping using all laser processes to fabricate customized bioelectronics. PEDOT:PSS is selectively irradiated by an ultraviolet (UV) pulse laser to form wet-stable conductive hydrogels that can softly interact with biological tissues (50 µm line width). The encapsulation layer is selectively patterned using the same laser source by UV-curing polymer networks (110 µm line width). For high stretchability (over 100%), mesh structures are made by the selective laser cutting process. Our rapid prototyping strategy minimizes the use of high-cost equipment, using only a single UV laser source to process the electrodes, encapsulation, and substrates that constitute bioelectronics without a photomask, enabling the prototyping stretchable microelectrode array with an area of 1 cm2 less than 10 min. We fabricated an optimized stretchable microelectrode array with low impedances (∼1.1 kΩ at 1 kHz) that can effectively record rat's cardiac signals with various health states.

Hydrogel/MOF Dual-Modified Photoelectrochemical Biosensor for Antibiofouling and Biocompatible Dopamine Detection.

For accurate in vivo detection, nonspecific adsorption of biomacromolecules such as proteins and cells is a severe issue. The adsorption leads to electrode passivation, significantly compromising both the sensitivity and precision of sensing. Meanwhile, common antibiofouling modifications, such as polymer coatings, still grapple with issues related to biocompatibility, electrode passivation, and miniaturization. Herein, we propose a composite antibiofouling coating strategy based on zwitterionic metal-organic frameworks (Z-MOFs) and a combination of acrylamide hydrogels. On a well-designed TiO2/Z-MOF/hydrogel photoelectrode, we achieve highly sensitive and selective detection of dopamine in complex biological environments. The hydrogel's three-dimensional porous structure combined with unique microporous architecture of Z-MOF ensures effective sieving of interfering macromolecules while preserving efficient small molecules and electron transport. This innovative approach paves the way for constructing miniature, in vivo antibiofouling sensors for molecule monitoring in living organisms with complicated chemical environments.

Innovative Vancomycin-Loaded Hydrogel-Based Systems - New Opportunities for the Antibiotic Therapy.

Purpose: Surgical site infections pose a significant challenge for medical services. Systemic antibiotics may be insufficient in preventing bacterial biofilm development. With the local administration of antibiotics, it is easier to minimize possible complications, achieve drugs' higher concentration at the injured site, as well as provide their more sustained release. Therefore, the main objective of the proposed herein studies was the fabrication and characterization of innovative hydrogel-based composites for local vancomycin (VAN) therapy. Methods: Presented systems are composed of ionically gelled chitosan particles loaded with vancomycin, embedded into biomimetic collagen/chitosan/hyaluronic acid-based hydrogels crosslinked with genipin and freeze-dried to serve in a flake/disc-like form. VAN-loaded carriers were characterized for their size, stability, and encapsulation efficiency (EE) using dynamic light scattering technique, zeta potential measurements, and UV-Vis spectroscopy, respectively. The synthesized composites were tested in terms of their physicochemical and biological features. Results: Spherical structures with sizes of about 200 nm and encapsulation efficiencies reaching values of approximately 60% were obtained. It was found that the resulting particles exhibit stability over time. The antibacterial activity of the developed materials against Staphylococcus aureus was established. Moreover, in vitro cell culture study revealed that the surfaces of all prepared systems are biocompatible as they supported the proliferation and adhesion of the model MG-63 cells. In addition, we have demonstrated significantly prolonged VAN release while minimizing the initial burst effect for the composites compared to bare nanoparticles and verified their desired physicochemical features during swellability, and degradation experiments. Conclusion: It is expected that the developed herein system will enable direct delivery of the antibiotic at an exposed to infections surgical site, providing drugs sustained release and thus will reduce the risk of systemic toxicity. This strategy would both inhibit biofilm formation and accelerate the healing process.

A Rapid Self-Assembling Peptide Hydrogel for Delivery of TFF3 to Promote Gastric Mucosal Injury Repair.

Self-assembled peptide-based nanobiomaterials exhibit promising prospects for drug delivery applications owing to their commendable biocompatibility and biodegradability, facile tissue uptake and utilization, and minimal or negligible unexpected toxicity. TFF3 is an active peptide autonomously secreted by gastric mucosal cells, possessing multiple biological functions. It acts on the surface of the gastric mucosa, facilitating the repair process of gastric mucosal damage. However, when used as a drug, TFF3 faces significant challenges, including short retention time in the gastric mucosal cavity and deactivation due to degradation by stomach acid. In response to this challenge, we developed a self-assembled short peptide hydrogel, Rqdl10, designed as a delivery vehicle for TFF3. Our investigation encompasses an assessment of its properties, biocompatibility, controlled release of TFF3, and the mechanism underlying the promotion of gastric mucosal injury repair. Congo red/aniline blue staining revealed that Rqdl10 promptly self-assembled in PBS, forming hydrogels. Circular dichroism spectra indicated the presence of a stable ß-sheet secondary structure in the Rqdl10 hydrogel. Cryo-scanning electron microscopy and atomic force microscopy observations demonstrated that the Rqdl10 formed vesicle-like structures in the PBS, which were interconnected to construct a three-dimensional nanostructure. Moreover, the Rqdl10 hydrogel exhibited outstanding biocompatibility and could sustainably and slowly release TFF3. The utilization of the Rqdl10 hydrogel as a carrier for TFF3 substantially augmented its proliferative and migratory capabilities, while concurrently bolstering its anti-inflammatory and anti-apoptotic attributes following gastric mucosal injury. Our findings underscore the immense potential of the self-assembled peptide hydrogel Rqdl10 for biomedical applications, promising significant contributions to healthcare science.

A 3D In-vitro model of the human dentine interface shows long-range osteoinduction from the dentine surface.

Emerging regenerative cell therapies for alveolar bone loss have begun to explore the use of cell laden hydrogels for minimally invasive surgery to treat small and spatially complex maxilla-oral defects. However, the oral cavity presents a unique and challenging environment for in vivo bone tissue engineering, exhibiting both hard and soft periodontal tissue as well as acting as key biocenosis for many distinct microbial communities that interact with both the external environment and internal body systems, which will impact on cell fate and subsequent treatment efficacy. Herein, we design and bioprint a facile 3D in vitro model of a human dentine interface to probe the effect of the dentine surface on human mesenchymal stem cells (hMSCs) encapsulated in a microporous hydrogel bioink. We demonstrate that the dentine substrate induces osteogenic differentiation of encapsulated hMSCs, and that both dentine and ß-tricalcium phosphate substrates stimulate extracellular matrix production and maturation at the gel-media interface, which is distal to the gel-substrate interface. Our findings demonstrate the potential for long-range effects on stem cells by mineralized surfaces during bone tissue engineering and provide a framework for the rapid development of 3D dentine-bone interface models.

Antioxidant Carbon Dots Nanozyme Loaded in Thermosensitive in situ Hydrogel System for Efficient Dry Eye Disease Treatment.

Purpose: Dry eye disease (DED) is a multifactorial ocular surface disease with a rising incidence. Therefore, it is urgent to construct a reliable and efficient drug delivery system for DED treatment. Methods: In this work, we loaded C-dots nanozyme into a thermosensitive in situ gel to create C-dots@Gel, presenting a promising composite ocular drug delivery system to manage DED. Results: This composite ocular drug delivery system (C-dots@Gel) demonstrated the ability to enhance adherence to the corneal surface and extend the ocular surface retention time, thereby enhancing bioavailability. Furthermore, no discernible ocular surface irritation or systemic toxicity was observed. In the DED mouse model induced by benzalkonium chloride (BAC), it was verified that C-dots@Gel effectively mitigated DED by stabilizing the tear film, prolonging tear secretion, repairing corneal surface damage, and augmenting the population of conjunctival goblet cells. Conclusion: Compared to conventional dosage forms (C-dots), the C-dots@Gel could prolong exhibited enhanced retention time on the ocular surface and increased bioavailability, resulting in a satisfactory therapeutic outcome for DED.

Injectable Hydrogel Loaded with CDs and FTY720 Combined with Neural Stem Cells for the Treatment of Spinal Cord Injury.

Purpose: Spinal cord injury (SCI) is an incurable and disabling event that is accompanied by complex inflammation-related pathological processes, such as the production of excessive reactive oxygen species (ROS) by infiltrating inflammatory immune cells and their release into the extracellular microenvironment, resulting in extensive apoptosis of endogenous neural stem cells. In this study, we noticed the neuroregeneration-promoting effect as well as the ability of the innovative treatment method of FTY720-CDs@GelMA paired with NSCs to increase motor function recovery in a rat spinal cord injury model. Methods: Carbon dots (CDs) and fingolimod (FTY720) were added to a hydrogel created by chemical cross-linking GelMA (FTY720-CDs@GelMA). The basic properties of FTY720-CDs@GelMA hydrogels were investigated using TEM, SEM, XPS, and FTIR. The swelling and degradation rates of FTY720-CDs@GelMA hydrogels were measured, and each group's ability to scavenge reactive oxygen species was investigated. The in vitro biocompatibility of FTY720-CDs@GelMA hydrogels was assessed using neural stem cells. The regeneration of the spinal cord and recovery of motor function in rats were studied following co-treatment of spinal cord injury using FTY720-CDs@GelMA hydrogel in combination with NSCs, utilising rats with spinal cord injuries as a model. Histological and immunofluorescence labelling were used to determine the regeneration of axons and neurons. The recovery of motor function in rats was assessed using the BBB score. Results: The hydrogel boosted neurogenesis and axonal regeneration by eliminating excess ROS and restoring the regenerative environment. The hydrogel efficiently contained brain stem cells and demonstrated strong neuroprotective effects in vivo by lowering endogenous ROS generation and mitigating ROS-mediated oxidative stress. In a follow-up investigation, we discovered that FTY720-CDs@GelMA hydrogel could dramatically boost NSC proliferation while also promoting neuronal regeneration and synaptic formation, hence lowering cavity area. Conclusion: Our findings suggest that the innovative treatment of FTY720-CDs@GelMA paired with NSCs can effectively improve functional recovery in SCI patients, making it a promising therapeutic alternative for SCI.

Hydrogel/microcarrier cell scaffolds for rapid expansion of satellite cells from large yellow croakers: Differential analysis between 2D and 3D cell culture.

Cell culture meat is based on the scaled-up expansion of seed cells. The biological differences between seed cells from large yellow croakers in the two-dimensional (2D) and three-dimensional (3D) culture systems have not been explored. Here, satellite cells (SCs) from large yellow croakers (Larimichthys crocea) were grown on cell climbing slices, hydrogels, and microcarriers for five days to analyze the biological differences of SCs on different cell scaffolds. The results exhibited that SCs had different cell morphologies in 2D and 3D cultures. Cell adhesion receptors (Itgb1andsdc4) and adhesion spot markervclof the 3D cultures were markedly expressed. Furthermore, myogenic decision markers (Pax7andmyod) were significantly enhanced. However, the expression of myogenic differentiation marker (desmin) was significantly increased in the microcarrier group. Combined with the transcriptome data, this suggests that cell adhesion of SCs in 3D culture was related to the integrin signaling pathway. In contrast, the slight spontaneous differentiation of SCs on microcarriers was associated with rapid cell proliferation. This study is the first to report the biological differences between SCs in 2D and 3D cultures, providing new perspectives for the rapid expansion of cell culture meat-seeded cells and the development of customized scaffolds.

A low-fouling electrochemical biosensor based on BSA hydrogel doped with carbon black for the detection of cortisol in human serum.

Electrochemical biosensors with high sensitivity can detect low concentrations of biomarkers, but their practical detection applications in complex biological environments such as human serum and sweat are severely limited by the biofouling. Herein, a conductive hydrogel based on bovine serum albumin (BSA) and conductive carbon black (CCB) was prepared for the construction of an antifouling biosensor. The BSA hydrogel (BSAG) was doped with CCB, and the prepared composite hydrogel exhibited good conductivity originated from the CCB and antifouling capability owing to the BSA hydrogel. An antifouling biosensor for the sensitive detection of cortisol was fabricated by drop-coating the conductive hydrogel onto a poly(3,4-ethylenedioxythiophene) (PEDOT) modified electrode and further immobilizing the cortisol aptamer. The constructed biosensor showed a linear range of 100 pg mL-1 - 10 µg mL-1 and a limit of detection of 26.0 pg mL-1 for the detection of cortisol, and it was capable of assaying cortisol accurately in complex human serum. This strategy of preparing antifouling and conductive hydrogels provides an effective way to develop robust electrochemical biosensors for biomarker detection in complex biological media.

Development of a Static Avascular and Dynamic Vascular Human Skin Equivalent Employing Collagen/Keratin Hydrogels.

One of the primary complications in generating physiologically representative skin tissue is the inability to integrate vasculature into the system, which has been shown to promote the proliferation of basal keratinocytes and consequent keratinocyte differentiation, and is necessary for mimicking representative barrier function in the skin and physiological transport properties. We created a 3D vascularized human skin equivalent (VHSE) with a dermal and epidermal layer, and compared keratinocyte differentiation (immunomarker staining), epidermal thickness (H&E staining), and barrier function (transepithelial electrical resistance (TEER) and dextran permeability) to a static, organotypic avascular HSE (AHSE). The VHSE had a significantly thicker epidermal layer and increased resistance, both an indication of increased barrier function, compared to the AHSE. The inclusion of keratin in our collagen hydrogel extracellular matrix (ECM) increased keratinocyte differentiation and barrier function, indicated by greater resistance and decreased permeability. Surprisingly, however, endothelial cells grown in a collagen/keratin extracellular environment showed increased cell growth and decreased vascular permeability, indicating a more confluent and tighter vessel compared to those grown in a pure collagen environment. The development of a novel VHSE, which incorporated physiological vasculature and a unique collagen/keratin ECM, improved barrier function, vessel development, and skin structure compared to a static AHSE model.

Synthesis and Physicochemical Characterization of Gelatine-Based Biodegradable Aerogel-like Composites as Possible Scaffolds for Regenerative Medicine.

Regenerative medicine is an interdisciplinary field aiming at restoring pathologically damaged tissues and whole organs by cell transplantation in combination with proper supporting scaffolds. Gelatine-based ones are very attractive due to their biocompatibility, rapid biodegradability, and lack of immunogenicity. Gelatine-based composite hydrogels, containing strengthening agents to improve their modest mechanical properties, have been demonstrated to act as extracellular matrices (ECMs), thus playing a critical role in "organ manufacturing". Inspired by the lysyl oxidase (LO)-mediated process of crosslinking, which occurs in nature to reinforce collagen, we have recently developed a versatile protocol to crosslink gelatine B (Gel B) in the presence or absence of LO, using properly synthesized polystyrene- and polyacrylic-based copolymers containing the amine or aldehyde groups needed for crosslinking reactions. Here, following the developed protocol with slight modifications, we have successfully crosslinked Gel B in different conditions, obtaining eight out of nine compounds in high yield (57-99%). The determined crosslinking degree percentage (CP%) evidenced a high CP% for compounds obtained in presence of LO and using the styrenic amine-containing (CP5/DMAA) and acrylic aldehyde-containing (CPMA/DMAA) copolymers as crosslinking agents. ATR-FTIR analyses confirmed the chemical structure of all compounds, while optical microscopy demonstrated cavernous, crater-like, and labyrinth-like morphologies and cavities with a size in the range 15-261 µm. An apparent density in the range 0.10-0.45 g/cm3 confirmed the aerogel-like structure of most samples. Although the best biodegradation profile was observed for the sample obtained using 10% CP5/DMAA (M3), high swelling and absorption properties, high porosity, and good biodegradation profiles were also observed for samples obtained using the 5-10% CP5/DMAA (M4, 5, 6) and 20% CPMA/DMAA (M9) copolymers. Collectively, in this work of synthesis and physicochemical characterization, new aerogel-like composites have been developed and, based on their characteristics, which fit well within the requirements for TE, five candidates (M3, M4, M5, M6, and M9) suitable for future biological experiments on cell adhesion, infiltration and proliferation, to confirm their effective functioning, have been identified.