Managing wounds remains a significant challenge in modern medicine. Biopolymer hydrogels provide a moist environment conducive to tissue healing. In this study, N-(3-trimethoxysilylpropyl)ethylenediamine (N-3-TMSPED) crosslinked sodium alginate hydrogels were synthesized via lyophilization, with varying concentrations of polyethylene glycol (PEG 600) to evaluate their role in angiogenesis and wound healing. Scanning electron microscopy confirmed porous structures essential for angiogenesis. The hydrogels showed maximum swelling at neutral and basic pH, and enhanced thermal stability with increasing PEG content. In vivo CAM assay results showed significantly increased blood vessels in PEG-containing hydrogels, with ANP2 exhibiting the highest vessel count (25.05 ± 0.0513) compared to control (13.02 ± 0.3600, p ≤ 0.05). PEG also ensured high embryo viability (94.6 %). Biochemical markers remained within normal physiological ranges, confirming hydrogel safety. All PEG-containing hydrogels displayed a significantly improved wound healing, affirming their therapeutic potential. Wound contraction analysis in mice showed ANP2 (loaded with XLC) achieved 72 % contraction by day 7 and 99.8 % by day 14, compared to untreated (57 %) and experimental controls (61 %) (p ≤ 0.05). Histology confirmed enhanced re-epithelialization and increased collagen deposition. These findings demonstrate that ANP hydrogels promote angiogenesis, accelerate wound healing, and exhibit excellent biocompatibility, highlighting their potential for tissue regeneration applications.

In this study, we aimed to develop soy protein-derived edible porous hydrogel scaffolds for cultured meat based on mechanical anisotropy to mimic the physical and biochemical properties of muscle tissues. Based on the traditional Japanese Ito-Kanten (thread agar) freeze-thaw process, we used liquid nitrogen directional freezing combined with ion crosslinking to fabricate an aligned scaffold composed of soy protein isolate (SPI), carrageenan (CA), and sodium alginate (SA). SPI, CA, and SA were dissolved in water, heated, mixed, and subjected to directional freezing in liquid nitrogen. The frozen gel was immersed in Ca2+ and K+ solutions for low-temperature crosslinking, followed by a second freezing step and lyophilization to create the SPI/CA/SA cryogel scaffold with anisotropic pore structure. Furthermore, C2C12 myoblasts were seeded onto the scaffold. After 14 d of dynamic culture, the cells exhibited significant differentiation along the aligned structure of the scaffold. Overall, our developed anisotropic scaffold provided a biocompatible environment to promote directed cell differentiation, showing potential for cultured meat production and serving as a sustainable protein source.

Mimicking bone remodeling scaffolds were developed as supportive biomaterials to promote tissue formation at defect sites in osteoporosis. Scaffolds made of polyvinyl alcohol (PVA) were mixed with varying weight ratios of silk fibroin (SF) and a phytoactive compound-based soy protein isolate (SPI); PVA30SF, PVA20SF10SPI, PVA15SF15SPI, PVA10SF20SPI, PVA30SPI. PVA was used as control. These components were mixed into aqueous solution and crosslinking with EDC before freeze thawing and freeze drying, respectively. Then, the scaffolds were characterized at the molecular level using Fourier transform infrared spectroscopy and their morphology was observed using scanning electron microscopy. Physical properties including swelling and degradation were tested, as well as mechanical properties like stress-strain behavior and modulus. The biological performance of the scaffolds was evaluated through osteoblast cell culturing, assessing cell viability, proliferation, alkaline phosphatase (ALP) activity, calcium content, and calcium deposition. The results demonstrate that the scaffolds with both SF and SPI had greater molecular mobility of -OH, amide I, II, and III groups, compared to the scaffold with only SF or SPI. These scaffolds also displayed larger pore sizes. Scaffolds with both SF and SPI showed higher swelling and degradation rates than those with only SF or SPI. Additionally, they exhibited better cell viability and calcium deposition, along with increased cell proliferation, ALP activity, and calcium content. Notably, the scaffold with a higher amount of SPI, PVA10SF20SPI, exhibited the most suitable performance for enhancing cell response, thereby promoting bone formation. This scaffold is proposed as a supportive biomaterial to be incorporated with plates and screws for bone fixation at defect sites in osteoporosis.

Ovarian cancer is a malignant tumor that arises in the female reproductive system and is associated with a very high mortality rate. This is primarily due to the highly invasive nature of metastasis and recurrence. Transforming the immune environment from an immunosuppressive state to an anti-tumor state through the phenotypic transformation of tumor-associated macrophages is crucial for inhibiting the growth, metastasis, and recurrence of ovarian cancer.

A polymer micelle (RC-PH-Ms) containing paclitaxel (PTX) and honokiol (HNK) was designed based on high expression of reactive oxygen species in the tumor microenvironment. Once the micelles are actively targeted to the tumor microenvironment characterized by elevated levels of reactive oxygen species, the responsive bond is cleaved, thereby exposing the secondary targeting ligand C7R. The released PTX and HNK facilitate the transformation of relevant macrophages in the tumor microenvironment from an M2 phenotype to an M1 phenotype, which in turn inhibits tumor growth, invasion and metastasis, inhibit angiogenesis and reduce tumor recurrence.

The effects of RC-PH-Ms on modulating the immune microenvironment and inhibiting tumor growth, invasion and metastasis, vascularization and recurrence were investigated both in vivo and in vitro.

RC-PH-Ms can significantly inhibit the metastasis and recurrence of ovarian cancer, which provides a new perspective for clinical treatment.

One of the key challenges in bone defects treatment is providing adequate and stable blood supply during new tissue regeneration. Mesenchymal stem cells (MSCs) and endothelial cells (ECs) have great potential to promote osteogenesis and angiogenesis during bone defect repair through paracrine effects, but their therapeutic efficacy depends on effective cellular assembly and delivery. In this work, we developed various microspheres with different pore sizes for multi-cellular delivery to enhance the angiogenic and osteogenic capability via combining microfluidic and gradient freeze-drying techniques. The particle and pore size of fabricated porous gelatin methacrylate (GelMA)-based hydrogel microspheres (PGMS) could be controllable through adjusting the freezing time of hydrogel microspheres, the range of particles and pores size are 150-250 μm and 10-100 μm with different freezing time from 0 min to 30 min. The optimized particle size (200.8 ± 14.2 μm) and pore size (11.2 ± 1.9 μm) were explored to promote cell assemble, adhesion, growth, and proliferation in the PGMS. Furthermore, the co-assembly and delivery of bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs) on the PGMS was achieved and an optimal cellular ratio of BMSCs to HUVECs (20:2) was established for co-culturing of them to achieve optimal paracrine effects, further promoting osteogenic differentiation and angiogenesis. Finally, results from both in vitro and in vivo experiments showed that the developed PGMS with co-assembly of BMSCs to HUVECs contributed to accelerate bone regeneration and vascularization process daringly, exhibited great potential in vascularized bone tissue reconstruction.

Corneal blindness affects over 10 million patients worldwide. Due to the limited supply of donor corneas and frequent graft failure, bioengineered alternatives are crucial. To overcome drawbacks associated with corneal substitutes from synthetic biomaterials, fabrication from plant-derived biomaterials is a potential alternative. Herein, soy protein and glutenin in combination with different crosslinkers were evaluated for fabrication of corneal substitutes. Optical, mechanical, and biochemical properties of fabricated constructs and control rabbit corneas were evaluated in vitro. Soy protein crosslinked with peroxidase/H202 possessed transparency and mechanical properties comparable to controls, although their water content and biocompatibility were inferior. In contrast, soy protein crosslinked with tannic acid showed similar water content, tensile strength, and biocompatibility as rabbit corneas; however, these constructs displayed significantly lower transparency and higher strain to failure. Finally, glutenin cross-linked using formaldehyde showed excellent transparency, strain to failure, and biocompatibility, however; they exhibited significantly lower water content and tensile strength than controls. This study is the first to establish CIELAB color values for the rabbit cornea, allowing quantitative optical evaluation of tissue-engineered substitutes. Thus, a crosslinking strategy utilizing plant-derived proteins for fabrication of constructs with properties comparable to rabbit corneas is a promising direction for development of tissue-engineered corneal substitutes.

In cultured meat (CM) production, Scaffolding plays an important role by aiding cell adhesion, growth, differentiation, and alignment. The existence of fibrous microstructure in connective and muscle tissues has attracted considerable interest in the realm of tissue engineering and triggered the interest of researchers to implement scaffolding techniques. A wide array of research efforts is ongoing in scaffolding technologies for achieving the real meat structure on the principality of biomedical research and to replace serum free CM production. Scaffolds made of animal-derived biomaterials are found efficient in replicating the extracellular matrix (ECM), thus focus should be paid to utilize animal byproducts for this purpose. Proper identification and utilization of plant-derived scaffolding biomaterial could be helpful to add diversified options in addition to animal derived sources and reduce in cost of CM production through scaffolds. Furthermore, techniques like electrospinning, modified electrospinning and 3D bioprinting should be focused on to create 3D porous scaffolds to mimic the ECM of the muscle tissue and form real meat-like structures. This review discusses recent advances in cutting edge scaffolding techniques and edible biomaterials related to structured CM production.

Wound healing is a major challenge worldwide, and people have been researching wound dressings that can promote wound healing for decades. Natural biobased materials, such as polysaccharides and proteins, have been widely used in the development of wound dressings. Among them, soy protein-based materials have attracted the interest of a wide range of researchers due to their safety, biocompatibility, controlled degradation, and ability to be mixed with other materials. However, there has been a lack of comments on these soy protein-based wound dressings. This work reviews various forms of soy protein-based wound dressings, such as hydrogels, films, and others, which could be prepared through physical/chemical cross-linking with synthetic or natural polymers. The important role played by soy protein-based materials in the wound healing phase and their properties will be examined, such as their anti-inflammatory, antioxidant, angiogenesis-promoting, cellular biocompatibility, self-healing ability, adhesion, antimicrobial, and tunable mechanical properties. Additionally, insights into the market prospects and trends for soy protein dressings are provided, clarifying the enormous development potential of soy protein as a new type of wound repair material.

Scaffolds play a key role in cultured meat production by providing an optimal environment for efficient cell attachment, growth, and development. This study investigated the effects of gelatin coating on the adhesion, proliferation, and adipogenic differentiation of adipose tissue-derived stem cells (ADSCs) cultured on soy protein-agarose scaffolds. Gelatin-coated scaffolds were prepared using 0.5% and 1.0% (w/v) gelatin solutions. The microstructure, water absorption rate, mechanical strength, cytotoxicity, cell adhesion, proliferation, and differentiation capabilities of the scaffolds were analyzed. Field emission scanning electron microscopy revealed the porous microstructure of the scaffolds, which was suitable for cell growth. Gelatin-coated scaffolds exhibited a significantly higher water absorption rate than that of non-coated scaffolds, indicating increased hydrophilicity. In addition, gelatin coating increased the mechanical strength of the scaffolds. Gelatin coating did not show cytotoxicity but significantly enhanced cell adhesion and proliferation. The gene expression levels of peroxisome proliferator-activated receptor gamma, CCAT/enhancer-binding protein alpha, and fatty acid-binding protein 4 were upregulated, and lipid accumulation was increased by gelatin coating. These findings suggest that gelatin-coated scaffolds provide a supportive microenvironment for ADSC growth and differentiation, highlighting their potential as a strategy for the improvement of cultured meat production and adipose tissue engineering.

Chronic skin wounds pose a global clinical challenge, necessitating effective treatment strategies. This study explores the potential of 3D printed Poly Lactic Acid (PLA) scaffolds, enhanced with Whey Protein Concentrate (WPC) at varying concentrations (25, 35, and 50% wt), for wound healing applications. PLA's biocompatibility, biodegradability, and thermal stability make it an ideal material for medical applications. The addition of WPC aims to mimic the skin's extracellular matrix and enhance the bioactivity of the PLA scaffolds. Fourier Transform Infrared Spectroscopy results confirmed the successful loading of WPC into the 3D printed PLA-based scaffolds. Scanning Electron Microscopy (SEM) images revealed no significant differences in pore size between PLA/WPC scaffolds and pure PLA scaffolds. Mechanical strength tests showed similar tensile strength between pure PLA and PLA with 50% WPC scaffolds. However, scaffolds with lower WPC concentrations displayed reduced tensile strength. Notably, all PLA/WPC scaffolds exhibited increased strain at break compared to pure PLA. Swelling capacity was highest in PLA with 25% WPC, approximately 130% higher than pure PLA. Scaffolds with higher WPC concentrations also showed increased swelling and degradation rates. Drug release was found to be prolonged with increasing WPC concentration. After seven days of incubation, cell viability significantly increased in PLA with 50% WPC scaffolds compared to pure PLA scaffolds. This innovative approach could pave the way for personalized wound care strategies, offering tailored treatments and targeted drug delivery. However, further studies are needed to optimize the properties of these scaffolds and validate their effectiveness in clinical settings.

3D printing is an additive manufacturing technology that locates constructed models with computer-controlled printing equipment. To achieve high-quality printing, the requirements on rheological properties of raw materials are extremely restrictive. Given the special structure and high modifiability under external physicochemical factors, the rheological properties of proteins can be easily adjusted to suitable properties for 3D printing. Although protein has great potential as a printing material, there are many challenges in the actual printing process. This review summarizes the technical considerations for protein-based ink 3D printing. The physicochemical factors used to enhance the printing adaptability of protein inks are discussed. The post-processing methods for improving the quality of 3D structures are described, and the application and problems of fourth dimension (4D) printing are illustrated. The prospects of 3D printing in protein manufacturing are presented to support its application in food and cultured meat. The native structure and physicochemical factors of proteins are closely related to their rheological properties, which directly link with their adaptability for 3D printing. Printing parameters include extrusion pressure, printing speed, printing temperature, nozzle diameter, filling mode, and density, which significantly affect the precision and stability of the 3D structure. Post-processing can improve the stability and quality of 3D structures. 4D design can enrich the sensory quality of the structure. 3D-printed protein products can meet consumer needs for nutritional or cultured meat alternatives.

Inks based on soybean protein isolate (SPI) were developed and their formulations were optimized as a function of the ink heat treatment and the content of other biopolymers to assess the effects of protein-polysaccharides and protein-protein interactions. First, the rheological behavior of the inks was analyzed in relation to the polyvinyl alcohol (PVA) concentration employed (20, 25, and 30 wt%) and, as a result of the analysis, the ink with 25 wt% PVA was selected. Additionally, sodium alginate (SA) and gelatin (GEL) were added to the formulations to improve the viscoelastic properties of the inks and the effect of the SA or GEL concentrations (1, 2, and 3 wt%) was studied. All inks showed shear thinning behavior and self-supporting abilities. Among all the 3D printed scaffolds, those with higher SA (3 wt%) or GEL (2 and 3 wt%) content showed higher shape fidelity and were selected for further characterization. Texture profile analysis demonstrated that the scaffolds prepared with previously heat-treated inks containing 3 wt% GEL showed the highest strength. Additionally, these scaffolds showed a higher water-uptake capacity profile.

The compositional formulations and the optimization of process parameters to fabricate hydrogel scaffolds with urological tissue-mimicking biophysical properties are not yet extensively explored, including a comprehensive assessment of a spectrum of properties, such as mechanical strength, viscoelasticity, antimicrobial property, and cytocompatibility. While addressing this aspect, the present work provides mechanistic insights into process science, to produce shape-fidelity compliant alginate-based biomaterial ink blended with gelatin and synthetic nanocellulose. The composition-dependent pseudoplasticity, viscoelasticity, thixotropy, and gel stability over a longer duration in physiological context have been rationalized in terms of intermolecular hydrogen bonding interactions among the biomaterial ink constituents. By varying the hybrid hydrogel ink composition within a narrow compositional window, the resulting hydrogel closely mimics the natural urological tissue-like properties, including tensile stretchability, compressive strength, and biophysical properties. Based on the printability assessment using a critical analysis of gel strength, we have established the buildability of the acellular hydrogel ink and have been successful in fabricating shape-fidelity compliant urological patches or hollow cylindrical grafts using 3D extrusion printing. Importantly, the new hydrogel formulations with good hydrophilicity, support fibroblast cell proliferation and inhibit the growth of Gram-negative E. coli bacteria. These attributes were rationalized in terms of nanocellulose-induced physicochemical changes on the scaffold surface. Taken together, the present study uncovers the process-science-based understanding of the 3D extrudability of the newly formulated alginate-gelatin-nanocellulose-based hydrogels with urological tissue-specific biophysical, cytocompatibility, and antibacterial properties.

Three-dimensional (3D) printing is a promising approach for the stabilization and delivery of non-living biologics. This versatile tool builds complex structures and customized resolutions, and has significant potential in various industries, especially pharmaceutics and biopharmaceutics. Biologics have become increasingly prevalent in the field of medicine due to their diverse applications and benefits. Stability is the main attribute that must be achieved during the development of biologic formulations. 3D printing could help to stabilize biologics by entrapment, support binding, or crosslinking. Furthermore, gene fragments could be transited into cells during co-printing, when the pores on the membrane are enlarged. This review provides: (i) an introduction to 3D printing technologies and biologics, covering genetic elements, therapeutic proteins, antibodies, and bacteriophages; (ii) an overview of the applications of 3D printing of biologics, including regenerative medicine, gene therapy, and personalized treatments; (iii) information on how 3D printing could help to stabilize and deliver biologics; and (iv) discussion on regulations, challenges, and future directions, including microneedle vaccines, novel 3D printing technologies and artificial-intelligence-facilitated research and product development. Overall, the 3D printing of biologics holds great promise for enhancing human health by providing extended longevity and enhanced quality of life, making it an exciting area in the rapidly evolving field of biomedicine.

To evaluate the antitumor and antimicrobial properties of an alginate-based membrane (ABM) loaded with bismuth lipophilic nanoparticles (BisBAL NPs) and cetylpyridinium chloride (CPC) on clinically isolated bacteria and a pancreatic cancer cell line.

The BisBAL NP-CPC ABM was characterized using optical and scanning electron microscopy (SEM). The antimicrobial potential was measured using the disk-diffusion assay, and antibiofilm activity was determined through the live/dead assay and fluorescence microscopy. The antitumor activity was analyzed on the pancreatic cell line (Panc 03.27) using the MTT assay and live/dead assay with fluorescence microscopy.

After a 24-h exposure (37°C, aerobic conditions), 5 µM BisBAL NP reduced the growth of K. pneumoniae by 77.9%, while 2.5 µM BisBAL NP inhibited the growth of Salmonella, E. faecalis and E. faecium by 82.9%, 82.6%, and 78%, respectively (p < 0.0001). The BisBAL NPs-CPC ABM (at a ratio of 10:1; 500 and 50 µM, respectively) inhibited the growth of all isolated bacteria, producing inhibition halos of 9.5, 11.2, 7, and 10.3 mm for K. pneumoniae, Salmonella, E. faecalis, and E. faecium, respectively, in contrast to the 6.5, 9.5, 8.5, and 9.8 mm obtained with 100 µM ceftriaxone (p < 0.0001). The BisBAL NPs-CPC ABM also reduced bacterial biofilms, with 81.4%, 74.5%, 97.1%, and 79.5% inhibition for K. pneumoniae, E. faecium, E. faecalis, and Salmonella, respectively. Furthermore, the BisBAL NPs-CPC ABM decreased Panc 03.27 cell growth by 76%, compared to 18% for drug-free ABM. GEM-ABM reduced tumoral growth by 73%. The live/dead assay confirmed that BisBAL NPs-CPC-ABM and GEM-ABM were cytotoxic for the turmoral Panc 03.27 cells.

An alginate-based membrane loaded with BisBAL NP and CPC exhibits dual antimicrobial and antitumoral efficacy. Therefore, it could be applied in cancer treatment and to diminish the occurrence of surgical site infections.

Currently, tissue engineering has been dedicated to the development of 3D structures through bioprinting techniques that aim to obtain personalized, dynamic, and complex hydrogel 3D structures. Among the different materials used for the fabrication of such structures, proteins and polysaccharides are the main biological compounds (biopolymers) selected for the bioink formulation. These biomaterials obtained from natural sources are commonly compatible with tissues and cells (biocompatibility), friendly with biological digestion processes (biodegradability), and provide specific macromolecular structural and mechanical properties (biomimicry). However, the rheological behaviors of these natural-based bioinks constitute the main challenge of the cell-laden printing process (bioprinting). For this reason, bioprinting usually requires chemical modifications and/or inter-macromolecular crosslinking. In this sense, a comprehensive analysis describing these biopolymers (natural proteins and polysaccharides)-based bioinks, their modifications, and their stimuli-responsive nature is performed. This manuscript is organized into three sections: (1) tissue engineering application, (2) crosslinking, and (3) bioprinting techniques, analyzing the current challenges and strengths of biopolymers in bioprinting. In conclusion, all hydrogels try to resemble extracellular matrix properties for bioprinted structures while maintaining good printability and stability during the printing process.

With growing significance in nervous system repair, mesenchymal stem cell-derived conditioned media (MSCCM) have been used in cell-free therapies in regenerative medicine. However, the immunomodulatory and neuroregenerative effects of MSCCM and the influence of priming on these effects are still poorly understood.

In this study, by various methods focused on cell viability, proliferation, neuron-like differentiation, neurite outgrowth, cell migration and regrowth, we demonstrated that MSCCM derived from adipose tissue (AT-MSCCM) and amniotic membrane (AM-MSCCM) had different effects on SH-SY5Y cells.

AT-MSCCM was found to have a higher proliferative capacity and the ability to impact neurite outgrowth during differentiation, while AM-MSCCM showed more pronounced immunomodulatory activity, migration, and re-growth of SH-SY5Y cells in the scratch model. Furthermore, priming of MSC with pro-inflammatory cytokine (IFN-γ) resulted in different proteomic profiles of conditioned media from both sources, which had the highest effect on SH-SY5Y proliferation and neurite outgrowth in terms of the length of neurites (pAT-MSCCM) compared to the control group (DMEM). Altogether, our results highlight the potential of primed and non-primed MSCCM as a therapeutic tool for neurodegenerative diseases, although some differences must be considered.

The fusion of protein science and peptide science opens up new frontiers in creating innovative biomaterials. Herein, a new kind of adhesive soft materials based on a natural occurring plant protein and short peptides via a simple co-assembly route are explored. The hydrophobic zein is supercharged by sodium dodecyl sulfate to form a stable protein colloid, which is intended to interact with charge-complementary short peptides via multivalent ionic and hydrogen bonds, forming adhesive materials at macroscopic level. The adhesion performance of the resulting soft materials can be fine-manipulated by customizing the peptide sequences. The adhesive materials can resist over 78 cmH2 O of bursting pressure, which is high enough to meet the sealing requirements of dural defect. Dural sealing and repairing capability of the protein-peptide biomaterials are further identified in rat and rabbit models. In vitro and in vivo assays demonstrate that the protein-peptide adhesive shows excellent anti-swelling property, low cell cytotoxicity, hemocompatibility, and inflammation response. In particular, the protein-peptide supramolecular biomaterials can in vivo dissociate and degrade within two weeks, which can well match with the time-window of the dural repairing. This work underscores the versatility and availability of the supramolecular toolbox in the easy-to-implement fabrication of protein-peptide biomaterials.

The formulation of hydrogels that meet the necessary flow characteristics for their extrusion-based 3D printing while providing good printability, resolution, accuracy and stability, requires long development processes. This work presents the technological development of a hydrogel-based ink of Laponite and alginate and evaluates its printing capacity. As a novelty, this article reports a standardizable protocol to quantitatively define the best printing parameters for the development of novel inks, providing new printability evaluation parameters such as the Printing Accuracy Escalation Index. As a result, this research develops a printable Laponite-Alginate hydrogel that presents printability characteristics. This ink is employed for the reproducible manufacture of 3D printed scaffolds with versatile and complex straight or curved printing patterns for a better adaptation to different final applications. Obtained constructs prove to be stable over time thanks to the optimization of a curing process. In addition, the study of the swelling and degradation behavior of the Laponite and alginate 3D printed scaffolds in different culture media allows the prediction of their behavior in future in vitro or in vivo developments. Finally, this study demonstrates the absence of cytotoxicity of the printed formulations, hence, setting the stage for their use in the field of biomedicine.

Sodium alginate (SA) is an inexpensive and biocompatible biomaterial with fast and gentle crosslinking that has been widely used in biological soft tissue repair/regeneration. Especially with the advent of 3D bioprinting technology, SA hydrogels have been applied more deeply in tissue engineering due to their excellent printability. Currently, the research on material modification, molding process and application of SA-based composite hydrogels has become a hot topic in tissue engineering, and a lot of fruitful results have been achieved. To better help readers have a comprehensive understanding of the development status of SA based hydrogels and their molding process in tissue engineering, in this review, we summarized SA modification methods, and provided a comparative analysis of the characteristics of various SA based hydrogels. Secondly, various molding methods of SA based hydrogels were introduced, the processing characteristics and the applications of different molding methods were analyzed and compared. Finally, the applications of SA based hydrogels in tissue engineering were reviewed, the challenges in their applications were also analyzed, and the future research directions were prospected. We believe this review is of great helpful for the researchers working in biomedical and tissue engineering.

Current hydrogel-based scaffolds offer a promising approach to accelerate tissue regeneration, but great challenges remain in developing platforms that mimic the physical microenvironment of tissues combined with therapeutic biological cues. Here, a 3D bioprinting gelatin-alginate hydrogel for the construction of gradient composite scaffolds that mimic the dermal stiffness microenvironment was developed for architecture construction by extruding the bioink on calcium-containing substrates to achieve gradient secondary cross-linking, meanwhile, adipose-derived stem cells were encapsulated in the present hydrogels for therapeutic purposes. The gradient-stiffness scaffold exhibited good stability and biocompatibility as well as enhanced proliferation and migration of the adipose-derived stem cells. In addition, the promoted angiogenesis and healing efficiency was demonstrated via the animal wound model and was mainly attributed to the enhanced paracrine secretion of adipose-derived stem cells by the physical microenvironment provided within the gradient stiffness scaffold. The current 3D printed gradient scaffolds provide adipose-derived stem cells with a distinct yet successive architecture rather than the typical uniform microenvironment to accelerate skin regeneration, which may have broader applications in other chronic wounds or tissue defects.

Three-dimensional (3D) bioprinting is a promising and rapidly evolving technology in the field of additive manufacturing. It enables the fabrication of living cellular constructs with complex architectures that are suitable for various biomedical applications, such as tissue engineering, disease modeling, drug screening, and precision regenerative medicine. The ultimate goal of bioprinting is to produce stable, anatomically-shaped, human-scale functional organs or tissue substitutes that can be implanted. Although various bioprinting techniques have emerged to develop customized tissue-engineering substitutes over the past decade, several challenges remain in fabricating volumetric tissue constructs with complex shapes and sizes and translating the printed products into clinical practice. Thus, it is crucial to develop a successful strategy for translating research outputs into clinical practice to address the current organ and tissue crises and improve patients' quality of life. This review article discusses the challenges of the existing bioprinting processes in preparing clinically relevant tissue substitutes. It further reviews various strategies and technical feasibility to overcome the challenges that limit the fabrication of volumetric biological constructs and their translational implications. Additionally, the article highlights exciting technological advances in the 3D bioprinting of anatomically shaped tissue substitutes and suggests future research and development directions. This review aims to provide readers with insight into the state-of-the-art 3D bioprinting techniques as powerful tools in engineering functional tissues and organs.

In recent years, 3D printing has gradually become a well-known new topic and a research hotspot. At the same time, the advent of 3D printing is inseparable from the preparation of bio-ink. Natural materials have the advantages of low toxicity or even non-toxicity, there being abundant raw materials, easy processing and modification, excellent mechanical properties, good biocompatibility, and high cell activity, making them very suitable for the preparation of bio-ink. With the help of 3D printing technology, the prepared materials and scaffolds can be widely used in tissue engineering and other fields. Firstly, we introduce the natural materials and their properties for 3D printing and summarize the physical and chemical properties of these natural materials and their applications in tissue engineering after modification. Secondly, we discuss the modification methods used for 3D printing materials, including physical, chemical, and protein self-assembly methods. We also discuss the method of 3D printing. Then, we summarize the application of natural materials for 3D printing in tissue engineering, skin tissue, cartilage tissue, bone tissue, and vascular tissue. Finally, we also express some views on the research and application of these natural materials.

In this study, cotton-reinforced alginate hydrogel fibers were successfully synthesized using the wet spinning technique to improve hydrogel fibers' mechanical strength and durability. Structural, chemical, and mechanical properties of the prepared fibers were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray Diffraction, differential scanning calorimeter, and single fiber strength tester. Based on the results obtained from fourier transform infrared spectroscopy and x-ray Diffraction, cotton fibers have been successfully incorporated into the structure of the hydrogel fibers. It was seen from the differential scanning calorimeter results that the incorporation of fibers in the structure even enhanced the thermal stability of the fiber and is viable to be implanted in the human body. Cotton reinforcement in alginate hydrogel fibers increases the modulus up to 56.45 MPa providing significant stiffness and toughness for the hydrogel composite fiber. The tenacity of the fibers increased by increasing the concentration of alginate from 2.1 cN/Tex (1% w/v) to 8.16 cN/Tex (1.5% w/v). Fiber strength increased by 26.75% and water absorbance increased by 120% by incorporating (10% w/w) cotton fibers into the fibrous structure. It was concluded that these cotton-reinforced alginate hydrogel fibers have improved mechanical properties and liquid absorption properties suitable for use in various biomedical applications.

Hydrogels have been extensively used as scaffolds in tissue engineering for cell adhesion, proliferation, migration, and differentiation because of their high-water content and biocompatibility similarity to the extracellular matrix. However, submicron or nanosized pore networks within hydrogels severely limit cell survival and tissue regeneration. In recent years, the application of macroporous hydrogels in tissue engineering has received considerable attention. The macroporous structure not only facilitates nutrient transportation and metabolite discharge but also provides more space for cell behavior and tissue formation. Several strategies for creating and functionalizing macroporous hydrogels have been reported. This review began with an overview of the advantages and challenges of macroporous hydrogels in the regulation of cellular behavior. In addition, advanced methods for the preparation of macroporous hydrogels to modulate cellular behavior were discussed. Finally, future research in related fields was discussed.

Lab-grown bovine meat analogues are emerging alternatives to animal sacrifices for cultured meat production. The most challenging aspect of the production process is the rapid proliferation of cells and establishment of the desired 3D structure for mass production. In this study, we developed a direct ink writing-based 3D-bioprinted meat culture platform composed of 6% (w/v) alginate and 4% (w/v) gelatin (Alg/Gel)-based hydrogel scaffolds supplemented with naturally derived protein hydrolysates (PHs; 10%) from highly nutritive plants (soybean, pigeon pea, and wheat), and some selected edible insects (beetles, crickets, and mealworms) on in vitro proliferation of bovine myosatellite cells (bMSCs) extracted from fresh meat samples. The developed bioink exhibited excellent shear-thinning behavior (n < 1) and mechanical stability during 3D bioprinting. Commercial proteases (Alcalase, Neutrase, and Flavourzyme) were used for protein hydrolysis. The resulting hydrolysates exhibited lower-molecular-weight bands (12-50 kDa) than those of crude isolates (55-160 kDa), as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The degree of hydrolysis was higher in the presence of Alcalase for both plant (34%) and insect (62%) PHs than other enzymes. The 3D-printed hydrogel scaffolds displayed excellent bioactivity and stability after 7 days of incubation. The developed prototype structure (pepperoni meat, 20 × 20 × 5 mm) provided a highly stable, nutritious, and mechanically strong structure that supported the rapid proliferation of myoblasts in a low-serum environment during the entire culture period. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay enhanced the free radical reduction of Alcalase- and Neutrase-treated PHs. Furthermore, the bioprinted bMSCs displayed early myogenesis (desmin and Pax7) in the presence of PHs, suggesting its role in bMSC differentiation. In conclusion, we developed a 3D bioprinted and bioactive meat culture platform using Alg/Gel/PHs as a printable and edible component for the mass production of cultured meat.

Biocompatible hydrogels have been considered one of the most well-known and promising in the various materials used in the fabrication of tissue-engineering scaffolds. Although considerable progress has been made in recent decades, many limitations remain, such as poor mechanical and degradation properties of biomaterials. In addition, vascularization of tissue-engineering scaffold is enduring challenge, which limited the fabrication and application of scaffold with clinically relevant dimension. To cover these challenges, in this work, a novel nanocomposite interpenetrating polymer networks (IPN) hydrogel scaffold consists of methacrylated gelatin (GelMA), poly(vinyl alcohol) (PVA) and copper oxide nanoparticles (CuONPs) was fabricated by extrusion-based 3D printing and contained favorable biological and physicochemical properties, such as mechanical, degradation, and cytocompatibility properties, particularly conducive to angiogenesis in the scaffold. A series of physiochemical and biological characterizations of the photo-crosslinked and hydrogen-bonded crosslinked IPN scaffolds were performed. Results showed that the mechanical and degradation properties of the nanocompsite GelMA/PVA scaffolds were obviously improved compare to GelMA scaffolds with single network. In vitro cell experiments and a chick embryo angiogenesis (CEA) assay confirmed good cytocompatibility of the fabricated scaffold with adipose-derived stem and human umbilical vein endothelial cells and its potential to promote cell migration and angiogenesis. In conclusion, all together of results demonstrated that GelMA/PVA IPN scaffolds modified with CuONPs have great potential for fabrication of volumetric scaffolds and promote angiogenesis during tissue growth and repair. This article is protected by copyright. All rights reserved.

Hernia repair mesh is associated with a number of complications, including adhesions and limited mobility, due to insufficient mechanical strength and non-resorbability. Among them, visceral adhesions are one of the most serious complications of patch repair. In this study, a degradable patch with an anti-adhesive layer was prepared for hernia repair by 3D printing and electrospinning techniques using polycaprolactone (PCL), polyvinyl alcohol (PVA), and soybean peptide (SP). The study into the physicochemical properties of the patch was found that it had adequate mechanical strength requirements (16 N cm^-1 ) and large elongation at break, which were superior than commercial polypropylene (PP) patches. In vivo and in vitro experiments showed that human umbilical vein endothelial cells (HUVECs) proliferated well on composite patches, and showed excellent biocompatibility with the host and little adhesion through a rat abdominal wall defect model. In conclusion, the results of this study show that composite patch can effectively reduce the occurrence of adhesions, while the addition of SP in the patch further enhances its biocompatibility. We believe that a regenerative biological patch with great potential in hernia repair provides a new strategy for the development of new biomimetic biodegradable patches. This article is protected by copyright. All rights reserved.