Progress in Gelatin as Biomaterial for Tissue Engineering

Regulation of osteoimmune microenvironment via functional dynamic hydrogel for diabetic bone regeneration

Bone regeneration and repair face formidable challenges under diabetic conditions, primarily due to the disruption of macrophage polarization induced by diabetes and the inflammatory imbalance within the bone microenvironment. We have developed a novel dynamic hydrogel system (AG-CD@LINA), constructed through the coordination crosslinking of thiolated gelatin (SH-Gelatin) and gold ions (Au3+), followed by grafting with cyclodextrin to load the ligand linagliptin. This hydrogel effectively inhibits the formation of M1 macrophages and the expression of pro-inflammatory cytokines by gradually releasing linagliptin. Simultaneously, it promotes the formation of M2 macrophages and the expression of anti-inflammatory cytokines, thus improving the inflammatory microenvironment of diabetic bone defects. Consequently, it facilitates the migration of mesenchymal stem cells and angiogenic cells, augments osteogenic activity, and promotes vascularization, collectively accelerating the regeneration of diabetic bone tissue. Mechanistically, polarization occurs through the TLR3-NF-κB signaling pathway. In vivo experiments demonstrate that the in-situ injection of the hydrogel enhances the regeneration of bone tissue and the restoration of bone structure in diabetic bone defects, effectively modulating local inflammation and promoting vascular formation. This study suggests that functionalized dynamic hydrogels can improve the inflammatory microenvironment by regulating in situ macrophage polarization, thereby facilitating the reconstruction of bone microstructure. This approach represents a promising novel therapeutic strategy for diabetic bone defects.

Lumbrokinase-containing gelatin nanofibers with multiple bioactivities for effective skin wound healing

Wound healing is a highly complex and intricate biological process involving cellular and molecular events. Given that lumbrokinase is a fibrinolytic enzyme derived from earthworms and exhibits notable anti-inflammatory, anti-fibrotic, and pro-angiogenic functions, this study aims to investigate the development of bioactive gelatin nanofibers containing lumbrokinase (GLK) fabricated through electrospinning as a novel nanomedicine strategy for enhancing wound healing. Our results showed that reducing electrospinning time can increase cross-linking degree and decrease degradation rate to maintain an effective concentration of released LK for supporting long-term biological processes. Cells cultured with biocompatible GLK displayed good adhesion and extensive spreading, increased VEGF production, and lowered IL-6 and TNF-α secretion. The GLK with superior and multiple bioactivities was further tested for tissue regeneration potential in a rat model of skin defect. The treatment of animals with GLK shortens wound healing time, reduces damage caused by inflammation, and increases collagen production, angiogenesis, and fibroblast proliferation/epithelialization, demonstrating that the healing effect on the local wounds is comparable to that of Comfeel group. Overall, the findings from preclinical studies suggest high promise of the LK-loaded biopolymer nanofibers as bioactive dressing materials for promoting a regenerative environment and accelerating wound healing, indicating its future translational potential.

Digital light processing of photo-crosslinkable gelatin to create biomimetic 3D constructs serving small intestinal tissue regeneration

Regeneration of small intestinal mucosal tissue could offer a promising strategy for Crohn's disease patients suffering from chronic inflammatory damage. Here, we aimed to develop hydrogels that mirror the villi and crypts of the small intestine and exhibit a physiological stiffness of G' ~ 1.52 kPa. For this purpose, we developed gelatin-methacryloyl-aminoethyl-methacrylate (gel-MA-AEMA)-, and gelatin-methacryloyl-norbornene (gel-MA-NB)-based biomaterial inks to fabricate 3D hydrogels ("villi only" versus "crypts and villi") with digital light processing (DLP) and co-cultured Caco-2/HT29-MTX cells. Gel-MA-AEMA was selected for its higher amount of methacrylates which was hypothesized to provide superior photo-crosslinking kinetics and hence superior DLP fabrication potential while gel-MA-NB was evaluated for its selective functionalization potential with thiolated bioactive compounds following DLP processing, resulting from its incorporated NB moieties which remain unreacted during the DLP process. Both gel-MA-AEMA-, and gel-MA-NB-based hydrogels exhibited a physiologically relevant stiffness, but only the gel-MA-AEMA-based biomaterial ink could be successfully utilized for printing hydrogels encompassing villi and crypts. Paracellular permeability of small sized marker molecules in combination with transepithelial electrical resistance measurements showed the formation of a functional barrier over time on all hydrogel constructs. Transmission electron microscopy and enterocyte differentiation marker genes' expression levels revealed the superior differentiation of Caco-2 on the 3D constructs compared to 2D hydrogel sheets. In summary, while both hydrogels enhanced functional barrier formation and enterocyte differentiation, gel-MA-AEMA proved more conducive to DLP compared to gel-MA-NB. Furthermore, our study underscored the benefits of cultivating intestinal cells on soft 3D constructs, enhancing cell barrier properties and differentiation, thus providing added value over traditional 2D supports.

Review of 3D-printed bioceramic/biopolymer composites for bone regeneration: fabrication methods, technologies and functionalized applications

Biomaterials for orthopedic applications must have biocompatibility, bioactivity, and optimal mechanical performance. A suitable biomaterial formulation is critical for creating desired devices. Bioceramics with biopolymer composites and biomimetics with components similar to that of bone tissue, have been recognized as an area of research for orthopedic applications. The combination of bioceramics with biopolymers has the advantage of satisfying the need for robust mechanical support and extracellular matrices at the same time. Three-dimensional (3D) printing is a powerful method for restoring large bone defects and skeletal abnormalities owing to the favorable merits of preparing large, porous, patient-specific, and other intricate architectures. Bioceramic/biopolymer composites produced using 3D printing technology have several advantages, including desirable optimal architecture, enhanced tissue mimicry, and improved biological and physical properties. This review describes various 3D printing bioceramic/biopolymer composites for orthopedic applications. We hope that these technologies will inspire the future design and fabrication of 3D printing bioceramic/biopolymer composites for clinical and commercial applications.

Control and interplay of scaffold-biomolecule interactions applied to cartilage tissue engineering

Cartilage tissue engineering based on the combination of biomaterials, adult or stem cells and bioactive factors is a challenging approach for regenerative medicine with the aim of achieving the formation of a functional neotissue stable in the long term. Various 3D scaffolds have been developed to mimic the extracellular matrix environment and promote cartilage repair. In addition, bioactive factors have been extensively employed to induce and maintain the cartilage phenotype. However, the spatiotemporal control of bioactive factor release remains critical for maximizing the regenerative potential of multipotent cells, such as mesenchymal stromal cells (MSCs), and achieving efficient chondrogenesis and sustained tissue homeostasis, which are essential for the repair of hyaline cartilage. Despite advances, the effective delivery of bioactive factors is limited by challenges such as insufficient retention at the site of injury and the loss of therapeutic efficacy due to uncontrolled drug release. These limitations have prompted research on biomolecule-scaffold interactions to develop advanced delivery systems that provide sustained release and controlled bioavailability of biological factors, thereby improving therapeutic outcomes. This review focuses specifically on biomaterials (natural, hybrid and synthetic) and biomolecules (molecules, proteins, nucleic acids) of interest for cartilage engineering. Herein, we review in detail the approaches developed to maintain the biomolecules in scaffolds and control their release, based on their chemical nature and structure, through steric, non-covalent and/or covalent interactions, with a view to their application in cartilage repair.

The application of tissue engineering strategies for uterine regeneration

Uterine injuries, particularly damages to endometrium, are usually associated with abnormal menstruation, recurrent miscarriage, pregnancy complications, and infertility. Tissue engineering using cell-based, biomolecule-based, or biomaterial and scaffold-based strategies has emerged as a novel and promising approach for uterine regeneration. Stem cells, biomolecules, and porous scaffolds used alone or, very often, used in combination as a more effective treatment means have shown great potential in promoting uterine regeneration. The reported preclinical studies have indicated that appropriate tissue engineering strategies could safely and effectively reconstruct not only endometrium but also partial or even the whole uterine structure. However, the progress in the uterine regeneration area is slow in comparison to that of regenerating many other body tissues and hence it still remains a great challenge to apply uterine tissue engineering for clinical applications. In this review, conventional treatments for uterine-related diseases are briefly reviewed and discussed first. Subsequently, tissue engineering strategies (cell-based, biomolecule-based, biomaterial and scaffold-based, or their combinations) for uterine repair in preclinical studies and clinical trials are presented and analyzed. Finally, the challenges and perspectives in uterine regeneration are pointed and discussed. Despite various limitations and obstacles, the tissue engineering approach is viable and holds high promise for uterine regeneration.

Preparation of thermoresponsive & enzymatically crosslinkable gelatin-gellan gum bioink: A protein-polysaccharide hydrogel for 3D bioprinting of complex soft tissues

Developing superior bioinks present several challenges in achieving ideal properties such as biocompatibility, viscosity, degradation rates & mechanical properties which are required to make functional tissue constructs. Various attempts have been made to prepare excellent bioink compositions that are suitable to address the above challenges. Herein, a versatile combination of gelatin (GL) - gellan gum (GG) bioink was successfully formulated & the bioink 7.5GL/2GG was found to be ideal for printing complex and highly intricate structures with excellent shape fidelity. Two different crosslinkers namely transglutaminase (TG) and calcium chloride (CaCl2) were utilized for crosslinking. The rheological properties of GL/GG bioink indicated that TG and dual (TG + CaCl2) crosslinked constructs had storage modulus equivalent to the that of native skin. Direct and indirect cytotoxicity assays revealed that the developed constructs were cytocompatible as well as hemocompatible. The 3D bioprinted GL/GG constructs crosslinked with only TG showed better cell viability, proliferation, cell spreading and wound healing efficiency in vitro compared to dual crosslinked constructs. In conclusion, TG crosslinking of 7.5GL/2GG bioink was ideal for bioprinting of skin tissue constructs for regenerative medicine applications. By altering the concentrations & printing conditions, this bioink may be tuned for other soft tissue engineering applications.

Retention of locally injected human iPS cell-derived cardiomyocytes into the myocardium using hydrolyzed gelatin

This study explored the impact of hydrolyzed gelatin (HG) concentration on the retention and therapeutic efficacy of human iPS cell-derived cardiomyocytes (hiPSC-CMs) when injected into the myocardium. The solubility of HG allows precise control over its concentration, influencing the distribution and leakage of injected solutions, which may affect therapeutic outcomes. Using both ex vivo and in vivo rat models, we investigated how varying HG concentrations affect the retention of solution and diffusion within the myocardium. In ex vivo static rat hearts, 10% HG minimized leakage but allowed significant diffusion. However, in pulsating in vivo hearts, 20% HG provided the best retention. In a rat myocardial infarction model, hiPSC-CMs suspended in 20% HG resulted in the highest cell retention. Echocardiogram showed a significant increase in the ejection fraction two weeks after transplantation compared to before transplantation. Additionally, cardiac magnetic resonance imaging (MRI) revealed that the ejection fraction was significantly higher than that of the sham group four weeks after transplantation. These findings suggest that optimizing HG concentration is crucial for enhancing the retention and therapeutic efficacy of hiPSC-CM transplants in treating heart disease.

Thiol-ene click chemistry: Enabling 3D printing of natural-based inks for biomedical applications

Over the last decade, 3D bioprinting has gained increasing popularity, being a technique capable of producing well-defined tissue-like structures. One of its most groundbreaking features is the ability to create personalized therapies tailored to the specific demands of individual patients. However, challenges including the selection of materials and crosslinking strategies, still need to be addressed to enhance ink characteristics and develop robust biomaterials. Herein, the authors showcase the potential of overcoming these challenges, focusing on the use of versatile, fast, and selective thiol-ene click chemistry to formulate inks for 3D bioprinting. The exploration of natural polymers, specifically proteins and polysaccharides, will be discussed and highlighted, outlining the advantages and disadvantages of this approach. Leveraging advanced thiol-ene click chemistry and natural polymers in the development of 3D printable bioinks may face the current challenges and is envisioned to pave the way towards innovative and personalized biomaterials for biomedical applications.

Digital light processing printing of non-modified protein-only compositions

This study explores the utilization of digital light processing (DLP) printing to fabricate complex structures using native gelatin as the sole structural component for applications in biological implants. Unlike approaches relying on synthetic materials or chemically modified biopolymers, this research harnesses the inherent properties of gelatin to create biocompatible structures. The printing process is based on a crosslinking mechanism using a di-tyrosine formation initiated by visible light irradiation. Formulations containing gelatin were found to be printable at the maximum documented concentration of 30 wt%, thus allowing the fabrication of overhanging objects and open embedded. Cell adhesion and growth onto and within the gelatin-based 3D constructs were evaluated by examining two implant fabrication techniques: (1) cell seeding onto the printed scaffold and (2) printing compositions that contain cells (cell-laden). The preliminary biological experiments indicate that both the cell-seeding and cell-laden strategies enable making 3D cultures of chondrocytes within the gelatin constructs. The mechanical properties of the gelatin scaffolds have a compressive modulus akin to soft tissues, thus enabling the growth and proliferation of cells, and later degrade as the cells differentiate and form a grown cartilage. This study underscores the potential of utilizing non-modified protein-only bioinks in DLP printing to produce intricate 3D objects with high fidelity, paving the way for advancements in regenerative tissue engineering.

Light Assisted Covalent Immobilization of Proteins for Biomedical Applications

The covalent immobilization of proteins attracts considerable interest in the biomedical field due to its potential applications in biosensors, recombinant protein purification, and the development of personalized therapeutic carriers. In response to the demand for more cost-effective, time-efficient, and simpler protocols, photo-immobilization emerges as a technique that circumvents the limitations of conventional methods. This approach offers enhanced precision at the nanoscale level and facilitates device reusability, thereby aligning with current sustainability concerns. Photo-immobilization is versatile, as it can be applied to both 2D and 3D substrates. While some methods involve complex protocols using genetically engineered photosensitive linkers, more straightforward techniques rely on amino acid bonds, such as disulfide bonds, for covalent protein bonding. Photo-immobilization can be achieved with both ultraviolet (UV) and visible light. This systematic review examines literature from Scopus, PubMed, and Web of Science, offering insights into relevant studies and considerations for covalent protein immobilization, and presents photochemical approaches applicable to major protein types.

Gelatin-based biomaterials as a delivery strategy for osteosarcoma treatment

Osteosarcoma is the most common primary malignant bone tumor. Although surgery and chemoradiotherapy have made some progress in the treatment of osteosarcoma. However, the high recurrence and metastasis rate of osteosarcoma and bone defects caused by surgery are still the main problems faced by osteosarcoma. Gelatin has excellent biocompatibility and biodegradability, and has made phased progress in tumor treatment. In the treatment of osteosarcoma, gelatin-based biomaterials can be used in delivery strategies to enhance the anti-tumor activity of osteosarcoma and can improve the appropriate compressive strength to improve the bone defects faced after surgery. At present, gelatin-based hydrogels, gelatin scaffolds, and gelatin-based nanoparticles have been reported in preclinical studies. In this article, we introduce the application of gelatin-based biomaterials in the treatment of osteosarcoma, and summarize and look forward to them.

Gelatin-alginate hydrogel for near-field electrospinning assisted 3D and 4-axis bioprinting

A near-field electrospinnable and three-dimensional (3D) bioprintable gelatin-alginate hydrogel was synthesized by controlling a moderate amount of alginate and a limited amount of crosslinker, tannic acid. This cytocompatible gelatin-alginate tough hydrogel exhibited excellent shape fidelity, a self-standing height exceeding 20 mm, and the capability for multilayer and four-axis 3D printing of complex scaffold shapes. The control of gel strength and rheology enables this hydrogel for successful stretching extrusion under an electric field in near-field electrospinning-induced 3D printing and four-axis printing. Nearly 74 % diameter reduction was achieved using near-field electrospinning-assisted 3D printing from a 20 mm distance, while a reduction of around 60 % was obtained in near-field electrospinning-assisted four-axis printing (with a 10 mm distance). Secondary crosslinking with Ca2+ ions provided the hydrogel ink with enhanced mechanical properties, improved post-printing shape fidelity, and prolonged degradation or disintegration (up to 21 days) of the 3D printed scaffolds. Tannic acid release from the degraded scaffold was very low (~2 mg at the end of 72 h). The success of multilayered and four-axis printing with near-field electrospinning, the controllable mechanical properties, high cytocompatibility, and cell supportiveness of this hydrogel suggest its strong potential for diverse applications, including complex scaffolds for tissue regeneration, porous tubes, controlled drug delivery, active membranes, flexible neurotransmitters, and strain sensors.

Injectable gelatin-pectin hydrogel for dental tissue engineering: Enhanced angiogenesis and antibacterial efficacy for pulpitis therapy

Pulpitis is inflammation of the dental pulp, often caused by bacterial infection from untreated cavities, leading to pain. The main challenge in treatment is eliminating infection while preserving tooth vitality. This study aims to address this challenge by developing a hydrogel for convenient insertion into the root canal system, securely attaching to dentin walls. An injectable hydrogel system is developed by chemically cross-linking natural polysaccharide pectin with gelatin (GPG) through reversible Schiff base reaction. The GPG system was then used to encapsulate and release drugs, such as ciprofloxacin (CIP) for infection prevention and deferoxamine (DFO) for promoting blood vessel proliferation and reducing inflammatory reactions. The GPGs absorbed significant amounts of CIP and DFO, enabling sustained release over a nearly ten-day period. When subcutaneously implanted, the GPGs formed stable gel depots, with only 50 % of the gels degrading after 3 weeks, indicating a sustained biodegradation pattern. Additionally, the GPG system demonstrated excellent antibacterial activity against both gram-negative and gram-positive bacteria. Results from in vitro scratch healing tests and in ovo chorioallantoic membrane chick model tests showed promising biocompatibility and promotion of vascular proliferation by the GPG. This study heralds a novel frontier in endodontic therapeutics, poised to potentially enable dental pulp regeneration.

Highly Flexible Methyl Cellulose/Gelatin Hydrogels for Potential Cartilage Tissue Engineering Applications

Cartilage damage resulting from trauma demonstrates a poor capacity for repair due to its avascular nature. Cartilage tissue engineering offers a unique therapeutic option for cartilage recovery. In this study, methylcellulose (MC)/gelatin (GEL) hydrogels (MC10G20, MC12.5G20, MC15G20, and MC17.5G20) were developed to assess and compare their chemical, mechanical, and biological characteristics for cartilage repair. First, the interaction between MC and GEL after blending and subsequent crosslinking with EDC/NHS was confirmed by using FTIR. Mechanical tests under compression test revealed that hydrogels' resistance to both elastic and plastic deformation increased with higher wt.% of MC. The % strain of the hydrogels doubled with the addition of MC, likely due to abundant hydrogen bonding between polymeric chains. Furthermore, the compressive modulus of MC/GEL hydrogels was approximately 0.2 MPa, closely matching modulus of human cartilage tissue. Similarly, the % water retention capacity of the hydrogels increased over the 7 days as the MC content increased. Additionally, SEM images showed that the incorporation of MC to GEL introduced porosity with the diameters ranging from 10 to 50 μm, similar to the size of pores in native cartilage. In vitro cell culture studies confirmed the biocompatibility of MC/GEL hydrogels. Fluorescence staining showed a 2.5-fold increase in F-actin staining following the incorporation of MC into the hydrogels. Overall, this study highlights the potential of MC/GEL hydrogels for cartilage tissue engineering, however, further research is required to assess its full potential.

State-of-the-Art Synthesis of Porous Polymer Materials and Their Several Fantastic Biomedical Applications: a Review

Porous polymers, including hydrogels, covalent organic frameworks (COFs), and hyper crosslinked polymers (HCPs), have become essential in biomedical research for their tunable pore architectures, large surface areas, and functional versatility. This review provides a comprehensive overview of their classification and updated synthesis mechanisms, such as 3D printing, electrospinning, and molecular imprinting. Their pivotal roles in drug delivery, tissue engineering, wound healing, and photodynamic/photothermal therapies, focusing on how pore size, distribution, and architecture impact drug release, cellular interactions, and therapeutic outcomes, are explored. Key challenges, including biocompatibility, mechanical strength, controlled degradation, and scalability, are critically assessed alongside emerging strategies to enhance clinical potential. Finally, recent challenges and future perspectives, emphasizing the broader biomedical applications of porous polymers, are addressed. This work provides valuable insights for advancing next-generation biomedical innovations through these materials.

Engineering considerations in the design of tissue specific bioink for 3D bioprinting applications

Over eight million surgical procedures are conducted annually in the United Stats to address organ failure or tissue losses. In response to this pressing need, recent medical advancements have significantly improved patient outcomes, primarily through innovative reconstructive surgeries utilizing tissue grafting techniques. Despite tremendous efforts, repairing damaged tissues remains a major clinical challenge for bioengineers and clinicians. 3D bioprinting is an additive manufacturing technique that holds significant promise for creating intricately detailed constructs of tissues, thereby bridging the gap between engineered and actual tissue constructs. In contrast to non-biological printing, 3D bioprinting introduces added intricacies, including considerations for material selection, cell types, growth, and differentiation factors. However, technical challenges arise, particularly concerning the delicate nature of living cells in bioink for tissue construction and limited knowledge about the cell fate processes in such a complex biomechanical environment. A bioink must have appropriate viscoelastic and rheological properties to mimic the native tissue microenvironment and attain desired biomechanical properties. Hence, the properties of bioink play a vital role in the success of 3D bioprinted substitutes. This review comprehensively delves into the scientific aspects of tissue-centric or tissue-specific bioinks and sheds light on the current challenges of the translation of bioinks and bioprinting.

Influence of Hydroxyapatite and Gelatin Content on Crosslinking Dynamics and HDFn Cell Viability in Alginate Bioinks for 3D Bioprinting

This study investigates how varying concentrations of hydroxyapatite (OHAp) and the addition of gelatin influence the ionic crosslinking time of alginate-based bioinks, as well as the shear stress experienced by neonatal human dermal fibroblasts (HDFn) during extrusion. These factors are crucial for validating bioinks and developing viable 3D bioprinted models. Four bioink formulations were created with a 50/50 ratio of alginate to gelatin, incorporating different calcium phosphate concentrations (0%, 1%, 5%, and 10%). The bioink compositions were confirmed via Fourier Transform Infrared (FT-IR) spectroscopy, and rheological analyses evaluated their pseudoplastic behavior, printability limits, and crosslinking times. The results indicated a notable increase in the consistency index (k) from 0.32 for the 0% OHAp formulation to 0.48 for the 10% OHAp formulation, suggesting improved viscoelastic properties. The elastic modulus recovery after crosslinking rose significantly from 245 Pa to 455 Pa. HDFn experienced a shear stress of up to 1.5436 Pa at the tip during extrusion with the HDFn-ALG5-GEL5-OHAp10 bioinks, calculated at a shear rate as low as 2 s-1. Viability assays confirmed over 70% cell viability 24 h post-extrusion and 92% viability after 7 days for the 10% OHAp formulation, highlighting the potential of hydroxyapatite-enhanced bioinks in tissue engineering applications.

Hydrogel-Enhanced Autologous Chondrocyte Implantation for Cartilage Regeneration-An Update on Preclinical Studies

Autologous chondrocyte implantation (ACI) and matrix-induced ACI (MACI) have demonstrated improved clinical outcomes and reduced revision rates for treating osteochondral and chondral defects. However, their ability to achieve lasting, fully functional repair remains limited. To overcome these challenges, scaffold-enhanced ACI, particularly utilizing hydrogel-based biomaterials, has emerged as an innovative strategy. These biomaterials are intended to mimic the biological composition, structural organization, and biomechanical properties of native articular cartilage. This review aims to provide comprehensive and up-to-date information on advancements in hydrogel-enhanced ACI from the past decade. We begin with a brief introduction to cartilage biology, mechanisms of cartilage injury, and the evolution of surgical techniques, particularly looking at ACI. Subsequently, we review the diversity of hydrogel scaffolds currently undergoing development and evaluation in preclinical studies for articular cartilage regeneration, emphasizing chondrocyte-laden hydrogels applicable to ACI. Finally, we address the key challenges impeding effective clinical translation, with particular attention to issues surrounding fixation and integration, aiming to inform and guide the future progression of tissue engineering strategies.

Evaluation of Different Concentrations of Antimicrobial Quaternary Polymers on the Behavior of Gelatin- and Starch-Based Films

Nowadays, incorporating quaternary ammonium groups into polymers is one of the most promising strategies for preparing antimicrobial biomaterials for general applications. The main objective of this work was to evaluate the effect of different concentrations of antimicrobial quaternary polymers in gelatin- and starch-based films for the development of active materials intended for applications in food packaging and medical fields. Two antimicrobial biobased polymers, called MeFPIAx (MeFPIA1 and MeFPIA2), were previously synthesized through the radical polymerization of itaconic acid (IA), followed by their subsequent functionalization and modification. Both polymers were incorporated into a new blend of gelatin and starch (15% w/w, 4:1 mass ratio), using glycerol (30% w/w) as a plasticizer. Films were prepared using the casting technique from aqueous dispersions of the polymers and their structure was characterized by Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR). The findings of this study showed the addition of MeFPIAx had a significant effect (p < 0.05), resulting in films with higher tensile strength (TS) and a higher Young's modulus (YM), with values close to 20 MPa and exceeding 250 MPa, respectively. On the other hand, elongation at break (EB) values lower than 80% were obtained. Additionally, the swelling was reduced from ~400% to 100% and a reduction in water vapor permeability (Pw) was observed, thanks to the increased interaction between the polymeric chains. Differential scanning calorimetry (DSC) scans showed that the addition of MeFPIAx increased the glass transition temperatures (Tg) from 29 °C to 65 °C. Furthermore, thermogravimetry analysis (TGA) indicated an increase in the initial degradation temperatures, suggesting that the films were more thermally resistant. Finally, the films exhibited slight antioxidant activity but significant antimicrobial activity, achieving bacterial reduction values greater than 70% with the incorporation of MeFPIAx polymers against Gram-positive Staphylococcus aureus.

Phloridzin functionalized gelatin-based scaffold for bone tissue engineering

Polyphenol-functionalized biomaterials are significant in the field of bone tissue engineering (BTE) due to their antioxidant, anti-inflammatory, and osteoinductive properties. In this study, a gelatin (Gel)-based scaffold was functionalized with phloridzin (Ph), the primary polyphenol in apple by-products, to investigate its influence on physicochemical and morphological, properties of the scaffold for BTE application. A preliminary assessment of the biological properties of the functionalized scaffold was also undertaken. The Ph-functionalized scaffold (Gel/Ph) exhibited a porous structure with high porosity (71.3 ± 0.3 %), a pore size of 206.5 ± 1.7 μm, and a radical scavenging activity exceeding 70 %. This scaffold with Young's modulus of 10.8 MPa was determined to support cell proliferation and exhibited cytocompatibility with mesenchymal stem cells (MSCs). Incorporating hydroxyapatite nanoparticle (HA) in the Gel/Ph scaffold stimulated the osteogenic differentiation of key osteogenic genes, including Runx2, ALPL, COL1A1, and OSX ultimately promoting mineralization. This research highlights the promising potential of utilizing polyphenolic compounds derived from fruit waste to functionalize scaffolds for BTE applications.

Quantitative Macromolecular Modeling Assay of Biopolymer-Based Hydrogels

The rubber elasticity theory has been lengthily applied to several polymeric hydrogel substances and upgraded from idealistic models to consider imperfections in the polymer network. The theory relies solely on hyperelastic material models in order to provide a description of the elastic polymer network. While this is also applicable to polymer gels, such hydrogels are rather characterized by their water content and visco-elastic mechanical properties. In this work, we applied rubber elasticity constitutive models through hyperelastic parameter identification of hydrogels based on their stress-strain response to compression. We further performed swelling experiments and determined the intrinsic properties, i.e., density, of the specimens and their components. Additionally, we estimated their equilibrium swelling and employed it in the swelling-equilibrium theory in order to determine the polymer-solvent interaction parameter of each hydrogel with regard to cross-linking. Our results show that the average mesh size obtained from the rubber elasticity theory can be regarded as a concentration-dependent characteristic length of the hydrogel's network and couples the non-linear elastic response to the specimens' inherent visco-elasticity through hysteresis as a quantifier of energy dissipation under large deformation.

The Effect of Carbodiimide Crosslinkers on Gelatin Hydrogel as a Potential Biomaterial for Gingival Tissue Regeneration

Connective tissue grafts for gingival recession treatment present significant challenges as they require an additional surgical site, leading to increased morbidity, extended operative times, and a more painful postoperative recovery for patients. Gelatin contains the arginine-glycine-aspartic acid (RGD) sequence, which supports cell adhesion and interactions. The development of gelatin hydrogels holds significant promise due to their biocompatibility, ease of customization, and structural resemblance to the extracellular matrix, making them a potential candidate for gingival regeneration. This study aimed to assess the physical and biological properties of crosslinked gelatin hydrogels using EDC/NHS with two crosslinker concentrations (GelCL12 and GelCL24) and compare these to non-crosslinked gelatin. Both groups underwent morphological, rheological, and chemical analysis. Biological assessments were conducted to evaluate human gingival fibroblast (HGF) proliferation, migration, and COL1 expression in response to the scaffolds. The crosslinked gelatin group exhibited greater interconnectivity and better physical characteristics without displaying cytotoxic effects on the cells. FTIR analysis revealed no significant chemical differences between the groups. Notably, the GelCL12 group significantly enhanced HGF migration and upregulated COL1 expression. Overall, GelCL12 met the required physical characteristics and biocompatibility, making it a promising scaffold for future gingival tissue regeneration applications.

Pristine Photopolymerizable Gelatin Hydrogels: A Low-Cost and Easily Modifiable Platform for Biomedical Applications

The study addresses the challenge of temperature sensitivity in pristine gelatin hydrogels, widely used in biomedical applications due to their biocompatibility, low cost, and cell adhesion properties. Traditional gelatin hydrogels dissolve at physiological temperatures, limiting their utility. Here, we introduce a novel method for creating stable hydrogels at 37 °C using pristine gelatin through photopolymerization without requiring chemical modifications. This approach enhances consistency and simplifies production and functionalization of the gelatin with bioactive molecules. The stabilization mechanism involves the partial retention of the triple-helix structure of gelatin below 25 °C, which provides specific crosslinking sites. Upon activation by visible light, ruthenium (Ru) acts as a photosensitizer that generates sulphate radicals from sodium persulphate (SPS), inducing covalent bonding between tyrosine residues and "locking" the triple-helix conformation. The primary focus of this work is the characterization of the mechanical properties, swelling ratio, and biocompatibility of the photopolymerized gelatin hydrogels. Notably, these hydrogels supported better cell viability and elongation in normal human dermal fibroblasts (NHDFs) compared to GelMA, and similar performance was observed for human pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). As a proof of concept for functionalization, gelatin was modified with selenous acid (GelSe), which demonstrated antioxidant and antimicrobial capacities, particularly against E. coli and S. aureus. These results suggest that pristine gelatin hydrogels, enhanced through this new photopolymerization method and functionalized with bioactive molecules, hold potential for advancing regenerative medicine and tissue engineering by providing robust, biocompatible scaffolds for cell culture and therapeutic applications.

Tissue engineering approaches for dental pulp regeneration: The development of novel bioactive materials using pharmacological epigenetic inhibitors

The drive for minimally invasive endodontic treatment strategies has shifted focus from technically complex and destructive root canal treatments towards more conservative vital pulp treatment. However, novel approaches to maintaining dental pulp vitality after disease or trauma will require the development of innovative, biologically-driven regenerative medicine strategies. For example, cell-homing and cell-based therapies have recently been developed in vitro and trialled in preclinical models to study dental pulp regeneration. These approaches utilise natural and synthetic scaffolds that can deliver a range of bioactive pharmacological epigenetic modulators (HDACis, DNMTis, and ncRNAs), which are cost-effective and easily applied to stimulate pulp tissue regrowth. Unfortunately, many biological factors hinder the clinical development of regenerative therapies, including a lack of blood supply and poor infection control in the necrotic root canal system. Additional challenges include a need for clinically relevant models and manufacturing challenges such as scalability, cost concerns, and regulatory issues. This review will describe the current state of bioactive-biomaterial/scaffold-based engineering strategies to stimulate dentine-pulp regeneration, explicitly focusing on epigenetic modulators and therapeutic pharmacological inhibition. It will highlight the components of dental pulp regenerative approaches, describe their current limitations, and offer suggestions for the effective translation of novel epigenetic-laden bioactive materials for innovative therapeutics.

Bioactive polymers: A comprehensive review on bone grafting biomaterials

The application of bone grafting materials in bone tissue engineering is paramount for treating severe bone defects. In this comprehensive review, we explore the significance and novelty of utilizing bioactive polymers as grafts for successful bone repair. Unlike metals and ceramics, polymers offer inherent biodegradability and biocompatibility, mimicking the native extracellular matrix of bone. While these polymeric micro-nano materials may face challenges such as mechanical strength, various fabrication techniques are available to overcome these shortcomings. Our study not only investigates diverse biopolymeric materials but also illuminates innovative fabrication methods, highlighting their importance in advancing bone tissue engineering.

Thermoresponsive and Supramolecular Polymers: Interesting Biomaterials for Drug Delivery

How to use and deliver drugs to diseased and damaged areas has been one of the main concerns of pharmacologists and doctors for a long time. With the efforts of researchers, the advancement of technology, and the involvement of engineering in the health field, diverse and promising approaches have been studied and used to achieve this goal. A better understanding of biomaterials and the ability of production equipment led researchers to offer new drug delivery systems to the world. In recent decades, responsive polymers (exclusively to temperature and pH) and supramolecular polymers have received much attention due to their unique capabilities. Although this field of research still needs to be scrutinized and studied more, their recognition, examination, and use as drug delivery systems is a start for a promising future. This review study, focusing on temperature-responsive and supramolecular biomaterials and their application as drug delivery systems, deals with their structure, properties, and role in the noninvasive and effective delivery of medicinal agents.

Cutting-Edge Hydrogel Technologies in Tissue Engineering and Biosensing: An Updated Review

Hydrogels, known for their unique ability to retain large amounts of water, have emerged as pivotal materials in both tissue engineering and biosensing applications. This review provides an updated and comprehensive examination of cutting-edge hydrogel technologies and their multifaceted roles in these fields. Initially, the chemical composition and intrinsic properties of both natural and synthetic hydrogels are discussed, highlighting their biocompatibility and biodegradability. The manuscript then probes into innovative scaffold designs and fabrication techniques such as 3D printing, electrospinning, and self-assembly methods, emphasizing their applications in regenerating bone, cartilage, skin, and neural tissues. In the realm of biosensing, hydrogels' responsive nature is explored through their integration into optical, electrochemical, and piezoelectric sensors. These sensors are instrumental in medical diagnostics for glucose monitoring, pathogen detection, and biomarker identification, as well as in environmental and industrial applications like pollution and food quality monitoring. Furthermore, the review explores cross-disciplinary innovations, including the use of hydrogels in wearable devices, and hybrid systems, and their potential in personalized medicine. By addressing current challenges and future directions, this review aims to underscore the transformative impact of hydrogel technologies in advancing healthcare and industrial practices, thereby providing a vital resource for researchers and practitioners in the field.

Enhancement in the Antibacterial Activity of Rifaximin by Delivery through Gelatin Nanoparticles

OBJECTIVES

Bacterial infections are a noteworthy global health concern that necessitates the development of new strategies to enhance the potency and efficacy of antibiotics. Rifaximin (RFX), a broad-spectrum antibiotic, exhibits promising antibacterial activity against several bacterial strains. However, its insolubility and impermeability impede the exploitation of its full potential. The objective of the current study is to overcome the inherent caveats of RFX in order to exploit its maximum potential.

SIGNIFICANCE

The exploitation of the full potential of antibiotics is necessary for reduction in their dosage and to minimize antibiotic pollution. This is a preliminary study aiming for maximum utilization of RFX at the target site and reduction in its release in unmetabolized form.

METHODS

Gelatin is a biopolymer that has gained significant attention for biomedical applications owing to its inherent biocompatibility and biodegradability. In this study, bovine gelatin nanoparticles (BGNPs) were fabricated by the self-assembly method for their application as a carrier of RFX to enhance its antibacterial activity. The study employs a comprehensive range of experimental techniques to characterize the fabricated BGNPs such as DLS, Zeta Potential, FT-IR, AFM, SEM-EDX, and UV-Vis spectrophotometry.

RESULTS

The average size of the fabricated BGNPs was 100 nm with a zeta potential value of -15.3 mV. The loading of RFX on BGNPs rendered an increase in its size to 136 nm with a zeta potential value of -16 mV. In-vitro assays and microscopic analyses were conducted to compare the antibacterial efficacy of RFX and RFX@BGNPs. An excellent loading capacity followed by sustained release of RFX from RFX@BGNPs rendered a significant enhancement in its pharmaceutical efficacy. The release of RFX from RFX@BGNPs followed the Higuchi and Korsmeyer-Peppasmodels. The antibacterial efficacy of RFX against Staphylococcus aureus has doubled by delivery through RFX@BGNPs, assessed by inhibitory and biofilm inhibitory assays. The enhancement in the antibacterial efficiency was further endorsed by SEM and microscopic imaging of the control and treated bacterial colonies.

CONCLUSION

The study demonstrates an enhancement in the antimicrobial efficacy of RFX by its delivery in the form of RFX@BGNPs to exploit its full potential for practical applications.

Fluorogenic in-situ Labelling of Gelatin Polymer in Aqueous Solution and Hydrogel

Gelatin polymers made from partially degraded collagen are important biomaterials, but their in-situ analysis suffers from uncontrollable covalent labelling and poor spatial-temporal imaging resolution. Herein, three tetrazolate-tagged tetraphenylethylene fluorophores (TPE-TAs) are introduced for practical fluorogenic labelling of gelatin in aqueous phase and hydrogels. These probes with aggregation-induced emission characteristics offer negligible background and elicit turn-on fluorescence by simply mixing with the gelatin in aqueous phase, giving a detection limit of 0.15 mg/L over a linear dynamic range up to 100 mg/L. This method does not work for collagens and causes minimal interference with gelatin properties. Mechanistic studies reveal a key role for multivalent electrostatic interactions between the abundant basic residues in gelatin (e. g., lysine, hydroxylysine, arginine) and anionic tetrazolate moieties of the lipophilic fluorophore synergistically in spatially rigid macromolecular encapsulation to achieve fluorogenic labelling. The AIE strategy by forming non-covalent fluorophore-gelatin complexes was developed for novel hydrogels that exhibited reversible fluorescence in response to dynamic microstructural changes in the hydrogel scaffold upon salting-in/out treatments, and enabled high spatial-temporal imaging of the fiber network in lyophilized samples. This work may open up avenues for in-situ imaging analysis and evaluation of gelatin-based biomaterials during processes such as in vivo degradation and mineralization.

Materials based on biodegradable polymers chitosan/gelatin: a review of potential applications

Increased mass manufacturing and the pervasive use of plastics in many facets of daily life have had detrimental effects on the environment. As a result, these worries heighten the possibility of climate change due to the carbon dioxide emissions from burning conventional, non-biodegradable polymers. Accordingly, biodegradable gelatin and chitosan polymers are being created as a sustainable substitute for non-biodegradable polymeric materials in various applications. Chitosan is the only naturally occurring cationic alkaline polysaccharide, a well-known edible polymer derived from chitin. The biological activities of chitosan, such as its antioxidant, anticancer, and antimicrobial qualities, have recently piqued the interest of researchers. Similarly, gelatin is a naturally occurring polymer derived from the hydrolytic breakdown of collagen protein and offers various medicinal advantages owing to its unique amino acid composition. In this review, we present an overview of recent studies focusing on applying chitosan and gelatin polymers in various fields. These include using gelatin and chitosan as food packaging, antioxidants and antimicrobial properties, properties encapsulating biologically active substances, tissue engineering, microencapsulation technology, water treatment, and drug delivery. This review emphasizes the significance of investigating sustainable options for non-biodegradable plastics. It showcases the diverse uses of gelatin and chitosan polymers in tackling environmental issues and driving progress across different industries.

Biohybrids for Combined Therapies of Skin Wounds: Agglomerates of Mesenchymal Stem Cells with Gelatin Hydrogel Beads Delivering Phages and Basic Fibroblast Growth Factor

There is great interest in developing effective therapies for the treatment of skin wounds accompanied by deep tissue losses and severe infections. We have attempted to prepare biohybrids formed of agglomerates of mesenchymal stem cells (MSCs) with gelatin hydrogel beads (GEL beads) delivering bacteriophages (phages) as antibacterial agents and/or basic fibroblast growth factor (bFGF) for faster and better healing, providing combined therapies for these types of skin wounds. The gelatin beads were produced through a two-step process using basic and/or acidic gelatins with different isoelectric points. Escherichia coli (E. coli) and its specific T4 phages were propagated. Phages and/or bFGF were loaded within the GELs and their release rates and modes were obtained. The phage release from the basic GEL beads was quite fast; in contrast, the bFGF release from the acidic GEL beads was sustained, as anticipated. MSCs were isolated from mouse adipose tissues and 2D-cultured. Agglomerates of these MSCs with GEL beads were formed and maturated in 3D cultures, and their time-dependent changes were followed. In these 3D culture experiments, it was observed that the agglomerates with GEL beads were very healthy and the MSCs formed tissue-like structures in 7 days, while the MSC agglomerates were not healthy and shrunk considerably as a result of cell death.

Nanofibrous Microspheres: A Biomimetic Platform for Bone Tissue Regeneration

Bone, a fundamental constituent of the human body, is a vital scaffold for support, protection, and locomotion, underscoring its pivotal role in maintaining skeletal integrity and overall functionality. However, factors such as trauma, disease, or aging can compromise bone structure, necessitating effective strategies for regeneration. Traditional approaches often lack biomimetic environments conducive to efficient tissue repair. Nanofibrous microspheres (NFMS) present a promising biomimetic platform for bone regeneration by mimicking the native extracellular matrix architecture. Through optimized fabrication techniques and the incorporation of active biomolecular components, NFMS can precisely replicate the nanostructure and biochemical cues essential for osteogenesis promotion. Furthermore, NFMS exhibit versatile properties, including tunable morphology, mechanical strength, and controlled release kinetics, augmenting their suitability for tailored bone tissue engineering applications. NFMS enhance cell recruitment, attachment, and proliferation, while promoting osteogenic differentiation and mineralization, thereby accelerating bone healing. This review highlights the pivotal role of NFMS in bone tissue engineering, elucidating their design principles and key attributes. By examining recent preclinical applications, we assess their current clinical status and discuss critical considerations for potential clinical translation. This review offers crucial insights for researchers at the intersection of biomaterials and tissue engineering, highlighting developments in this expanding field.

Nanomaterials-Based Hybrid Bioink Platforms in Advancing 3D Bioprinting Technologies for Regenerative Medicine

3D bioprinting is recognized as the ultimate additive biomanufacturing technology in tissue engineering and regeneration, augmented with intelligent bioinks and bioprinters to construct tissues or organs, thereby eliminating the stipulation for artificial organs. For 3D bioprinting of soft tissues, such as kidneys, hearts, and other human body parts, formulations of bioink with enhanced bioinspired rheological and mechanical properties were essential. Nanomaterials-based hybrid bioinks have the potential to overcome the above-mentioned problem and require much attention among researchers. Natural and synthetic nanomaterials such as carbon nanotubes, graphene oxides, titanium oxides, nanosilicates, nanoclay, nanocellulose, etc. and their blended have been used in various 3D bioprinters as bioinks and benefitted enhanced bioprintability, biocompatibility, and biodegradability. A limited number of articles were published, and the above-mentioned requirement pushed us to write this review. We reviewed, explored, and discussed the nanomaterials and nanocomposite-based hybrid bioinks for the 3D bioprinting technology, 3D bioprinters properties, natural, synthetic, and nanomaterial-based hybrid bioinks, including applications with challenges, limitations, ethical considerations, potential solution for future perspective, and technological advancement of efficient and cost-effective 3D bioprinting methods in tissue regeneration and healthcare.

Fabrication of vascularized tissue-engineered bone models using triaxial bioprinting

Bone tissue is a highly vascularized tissue. When constructing tissue-engineered bone models, both the osteogenic and angiogenic capabilities of the construct should be carefully considered. However, fabricating a vascularized tissue-engineered bone to promote vascular formation and bone generation, while simultaneously establishing nutrition channels to facilitate nutrient exchange within the constructs, remains a significant challenge. Triaxial bioprinting, which not only allows the independent encapsulation of different cell types while simultaneously forming nutrient channels, could potentially emerge as a strategy for fabricating vascularized tissue-engineered bone. Moreover, bioinks should also be applied in combination to promote both osteogenesis and angiogenesis. In this study, employing triaxial bioprinting, we used a blend bioink of gelatin methacryloyl (GelMA), sodium alginate (Alg), and different concentrations of nano beta-tricalcium phosphate (nano β-TCP) encapsulated MC3T3-E1 preosteoblasts as the outer layer, a mixed bioink of GelMA and Alg loaded with human umbilical vein endothelial cells (HUVEC) as the middle layer, and gelatin as a sacrificial material to form nutrient channels in the inner layer to fabricate vascularized bone constructs simulating the microenvironment for bone and vascular tissues. The results showed that the addition of nano β-TCP could adjust the mechanical, swelling, and degradation properties of the constructs. Biological assessments revealed the cell viability of constructs containing different concentrations of nano β-TCP was higher than 90% on day 7, The cell-laden constructs containing 3% (w/v) nano β-TCP exhibited better osteogenic (higher Alkaline phosphatase activity and larger Osteocalcin positive area) and angiogenic (the gradual increased CD31 positive area) potential. Therefore, using triaxial bioprinting technology and employing GelMA, Alg, and nano β-TCP as bioink components could fabricate vascularized bone tissue constructs, offering a novel strategy for vascularized bone tissue engineering.

Recent Advances in Implantable 3D-Printed Scaffolds for Repair of Spinal Cord Injury

Spinal cord injury (SCI) is an important factor in sensory and motor disorders that affects thousands of people every year. Currently, despite successes in basic science and clinical research, there are few effective methods in the treatment of chronic and acute spinal cord injuries. In the last decade, the use of 3D printed scaffolds in the treatment of SCI had satisfactory and promising results. By providing a microenvironment around the injury site and in combination with growth factors or cells, 3D printed scaffolds help in axon regeneration as well as neural recovery after SCI. Here, we provide an overview of tissue engineering, 3D printing scaffolds, the different polymers used and their characterization methods. This review highlights the recent encouraging applications of 3D printing scaffolds in developing the novel SCI therapy.

A Gelatin-Based Biomimetic Scaffold Promoting Osteogenic Differentiation of Adipose-Derived Mesenchymal Stem Cells

Background

In bone tissue engineering segment, numerous approaches have been investigated to address critically sized bone defects via 3D scaffolds, as the amount of autologous bone grafts are limited, accompanied with complications on harvesting. Moreover, the use of bone-marrow-derived stem cells is also a limiting factor owing to the invasive procedures involved and the low yield of stem cells. Hence, research is ongoing on the search for an ideal bone graft system promoting bone growth and regeneration.

Purpose of the Study

This study aims to develop a unique platform for tissue development via stem cell differentiation towards an osteogenic phenotype providing optimum biological cues for cell adhesion, differentiation and proliferation using biomimetic gelatin-based scaffolds. The use of adipose-derived mesenchymal stem cells in this study also offers an ideal approach for the development of an autologous bone graft.

Methods

A gelatin-vinyl acetate-based 3D scaffold system incorporating Bioglass was developed and the osteogenic differentiation of adipose-derived mesenchymal stem cells (ADMSCs) on the highly porous freeze-dried gelatin-vinyl acetate/ Bioglass scaffold (GB) system was analyzed. The physicochemical properties, cell proliferation and viability were investigated by seeding rat adipose tissue-derived mesenchymal stem cells (ADSCs) onto the scaffolds. The osteogenic differentiation potential of the ADMSC seeded GeVAc/bioglass system was assessed using calcium deposition assay and bone-related protein and genes and comparing with the 3D Gelatin vinyl acetate coppolymer (GeVAc) constructs.

Results and Conclusion

According to the findings, the 3D porous GeVAc/bioglass scaffold can be considered as a promising matrix for bone tissue regeneration and the 3D architecture supports the differentiation of the ADMSCs into osteoblast cells and enhances the production of mineralized bone matrix.

Impact of Hydroxyapatite on Gelatin/Oxidized Alginate 3D-Printed Cryogel Scaffolds

Fabrication of scaffolds via 3D printing is a promising approach for tissue engineering. In this study, we combined 3D printing with cryogenic crosslinking to create biocompatible gelatin/oxidized alginate (Gel/OxAlg) scaffolds with large pore sizes, beneficial for bone tissue regeneration. To enhance the osteogenic effects and mechanical properties of these scaffolds, we evaluated the impact of hydroxyapatite (HAp) on the rheological characteristics of the 2.86% (1:1) Gel/OxAlg ink. We investigated the morphological and mechanical properties of scaffolds with low, 5%, and high 10% HAp content, as well as the resulting bio- and osteogenic effects. Scanning electron microscopy revealed a reduction in pore sizes from 160 to 180 µm (HAp-free) and from 120 to 140 µm for both HAp-containing scaffolds. Increased stability and higher Young's moduli were measured for 5% and 10% HAp (18 and 21 kPa, respectively) compared to 11 kPa for HAp-free constructs. Biological assessments with mesenchymal stem cells indicated excellent cytocompatibility and osteogenic differentiation in all scaffolds, with high degree of mineralization in HAp-containing constructs. Scaffolds with 5% HAp exhibited improved mechanical characteristics and shape fidelity, demonstrated positive osteogenic impact, and enhanced bone tissue formation. Increasing the HAp content to 10% did not show any advantages in osteogenesis, offering a minor increase in mechanical strength at the cost of significantly compromised shape fidelity.

Fabrication of polymeric microspheres for biomedical applications

Polymeric microspheres (PMs) have attracted great attention in the field of biomedicine in the last several decades due to their small particle size, special functionalities shown on the surface and high surface-to-volume ratio. However, how to fabricate PMs which can meet the clinical needs and transform laboratory achievements to industrial scale-up still remains a challenge. Therefore, advanced fabrication technologies are pursued. In this review, we summarize the technologies used to fabricate PMs, including emulsion-based methods, microfluidics, spray drying, coacervation, supercritical fluid and superhydrophobic surface-mediated method and their advantages and disadvantages. We also review the different structures, properties and functions of the PMs and their applications in the fields of drug delivery, cell encapsulation and expansion, scaffolds in tissue engineering, transcatheter arterial embolization and artificial cells. Moreover, we discuss existing challenges and future perspectives for advancing fabrication technologies and biomedical applications of PMs.

Increasing Collagen to Bioink Drives Mesenchymal Stromal Cells-Chondrogenesis from Hyaline to Calcified Layers

The bioextrusion of mesenchymal stromal cells (MSCs) directly seeded in a bioink enables the production of three-dimensional (3D) constructs, promoting their chondrogenic differentiation. Our study aimed to evaluate the effect of different type I collagen concentrations in the bioink on MSCs' chondrogenic differentiation. We printed 3D constructs using an alginate, gelatin, and fibrinogen-based bioink cellularized with MSCs, with four different quantities of type I collagen addition (0.0, 0.5, 1.0, and 5.0 mg per bioink syringe). We assessed the influence of the bioprinting process, the bioink composition, and the growth factor (TGF-ꞵ1) on the MSCs' survival rate. We confirmed the biocompatibility of the process and the bioinks' cytocompatibility. We evaluated the chondrogenic effects of TGF-ꞵ1 and collagen addition on the MSCs' chondrogenic properties through macroscopic observation, shrinking ratio, reverse transcription polymerase chain reaction, glycosaminoglycan synthesis, histology, and type II collagen immunohistochemistry. The bioink containing 0.5 mg of collagen produces the richest hyaline-like extracellular matrix, presenting itself as a promising tool to recreate the superficial layer of hyaline cartilage. The bioink containing 5.0 mg of collagen enhances the synthesis of a calcified matrix, making it a good candidate for mimicking the calcified cartilaginous layer. Type I collagen thus allows the dose-dependent design of specific hyaline cartilage layers.

Fabrication and characterization of a bioactive composite scaffold based on polymeric collagen/gelatin/nano β-TCP for alveolar bone regeneration

One strategy to correct alveolar bone defects is use of bioactive bone substitutes to maintain the structure of defect site and facilitate cells and vessels' ingrowth. This study aimed to fabricate and characterize the freeze-dried bone regeneration scaffolds composed of polymeric Type I collagen, nano Beta-tricalcium phosphate (β-TCP), and gelatin. The stable structures of scaffolds were obtained by thermal crosslinking and EDC/NHS ((1-ethyl-3-(3-dimethylaminopropyl) carbodiimide)/(N-hydroxysuccinimide)) chemical crosslinking processes. Subsequently, the physicochemical and biological properties of the scaffolds were characterized and assessed. The results indicated the bioactive composite scaffolds containing 10% and 20% (w/v) nano β-TCP exhibited suitable porosity (84.45 ± 25.43 nm, and 94.51 ± 14.69 nm respectively), a rapid swelling property (reaching the maximum swelling rate at 1 h), excellent degradation resistance (residual mass percentage of scaffolds higher than 80% on day 90 in PBS and Type I collagenase solution respectively), and sustained calcium release capabilities. Moreover, they displayed outstanding biological properties, including superior cell viability, cell adhesion, and cell proliferation. Additionally, the scaffolds containing 10% and 20% (w/v) nano β-TCP could promote the osteogenic differentiation of MC3T3-E1. Therefore, the bioactive composite scaffolds containing 10% and 20% (w/v) nano β-TCP could be further studied for being used to treat alveolar bone defects in vivo.

Evaluating physiochemical characteristics of tragacanth gum-gelatin network hydrogels designed through graft copolymerization technique

The present work deals with the evaluation of the physiochemical and biomedical properties of hydrogels derived from copolymerization of tragacanth gum (TG) and gelatin for use in drug delivery (DD) applications. Copolymers were characterized by field emission-scanning electron micrographs (FE-SEM), electron dispersion X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), 13C-nuclear magnetic resonance (NMR), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. FE-SEM revealed heterogeneous morphology and XRD analysis demonstrated an amorphous nature with short range pattern of polymer chains within the copolymers. The release of the drug ofloxacin occurred through a non-Fickian diffusion mechanism and the release profile was best described by the Korsmeyer-Peppas kinetic model. The hydrogels exhibited blood compatibility and demonstrated a thrombogenicity value of 75.63 ± 1.98 % during polymer-blood interactions. Polymers revealed mucoadhesive character during polymer-mucous membrane interactions and required 119 ± 8.54 mN detachment forces to detach from the biological membrane. The copolymers illustrated the antioxidant properties as evidenced by 2, 2'-diphenylpicrylhydrazyl (DPPH) assay which demonstrated a 65.71 ± 3.68 % free radical inhibition. Swelling properties analysis demonstrated that by change in monomer and cross linker content during the reaction increased the crosslinking of the network. These results suggest that the pore size of network hydrogels could be controlled as per the requirement of DD systems. The copolymers were prepared at optimized reaction conditions using 14.54 × 10-1 molL-1 of acrylic acid monomer and 25.0 × 10-3 molL-1 of crosslinker NNMBA. The optimized hydrogels exhibited a crosslink density of 2.227 × 10-4 molcm-3 and a mesh size of 7.966 nm. Additionally, the molecular weight between two neighboring crosslinks in the hydrogels was determined to be 5332.209 gmol-1.The results indicated that the combination of protein-polysaccharide has led to the development of hydrogels suitable for potential applications in sustained drug delivery.

Current research status and development prospects of embolic microspheres containing biological macromolecules and others

Transcatheter arterial embolization (TACE) has been used in the treatment of malignant tumors, sudden hemorrhage, uterine fibroids, and other diseases, and with advances in imaging techniques and devices, materials science, and drug release technology, more and more embolic agents that are drug-carrying, self-imaging, or have multiple functions are being developed. Microspheres provide safer and more effective therapeutic results as embolic agents, with their unique spherical appearance and good embolic properties. Embolic microspheres are the key to arterial embolization, blocking blood flow and nutrient supply to the tumor target. This review summarizes some of the currently published embolic microspheres, classifies embolic microspheres according to matrix, and summarizes the characteristics of the microsphere materials, the current status of research, directions, and the value of existing and potential applications. It provides a direction to promote the development of embolic microspheres towards multifunctionalization, and provides a reference to promote the research and application of embolic microspheres in the treatment of tumors.

Developing active and intelligent biodegradable packaging from food waste and byproducts: A review of sources, properties, film production methods, and their application in food preservation

Food waste and byproducts (FWBP) are a global issue impacting economies, resources, and health. Recycling and utilizing these wastes, due to processing and economic constraints, face various challenges. However, valuable components in food waste inspire efficient solutions like active intelligent packaging. Though research on this is booming, its material selectivity, effectiveness, and commercial viability require further analysis. This paper categorizes FWBP and explores their potential for producing packaging from both animal and plant perspectives. In addition, the preparation/fabrication methods of these films/coatings have also been summarized comprehensively, focusing on the advantages and disadvantages of these methods and their commercial adaptability. Finally, the functions of these films/coatings and their ultimate performance in protecting food (meat, dairy products, fruits, and vegetables) are also reviewed systematically. FWBP provide a variety of methods for the application of edible films, including being made into coatings, films, and fibers for food preservation, or extracting active substances directly or indirectly from them (in the form of encapsulation) and adding them to packaging to endow them with functions such as barrier, antibacterial, antioxidant, and pH response. In addition, the casting method is the most commonly used method for producing edible films, but more film production methods (extrusion, electrospinning, 3D printing) need to be tried to make up for the shortcomings of the current methods. Finally, researchers need to conduct more in-depth research on various active compounds from FWBP to achieve better application effects and commercial adaptability.

Gelatin-based biomaterials and gelatin as an additive for chronic wound repair

Disturbing or disrupting the regular healing process of a skin wound may result in its progression to a chronic state. Chronic wounds often lead to increased infection because of their long healing time, malnutrition, and insufficient oxygen flow, subsequently affecting wound progression. Gelatin-the main structure of natural collagen-is widely used in biomedical fields because of its low cost, wide availability, biocompatibility, and degradability. However, gelatin may exhibit diverse tailored physical properties and poor antibacterial activity. Research on gelatin-based biomaterials has identified the challenges of improving gelatin's poor antibacterial properties and low mechanical properties. In chronic wounds, gelatin-based biomaterials can promote wound hemostasis, enhance peri-wound antibacterial and anti-inflammatory properties, and promote vascular and epithelial cell regeneration. In this article, we first introduce the natural process of wound healing. Second, we present the role of gelatin-based biomaterials and gelatin as an additive in wound healing. Finally, we present the future implications of gelatin-based biomaterials.

Mimicking the Physicochemical Properties of the Cornea: A Low-Cost Approximation Using Highly Available Biopolymers

Corneal diseases represent a significant global health challenge, often resulting in blindness, for which penetrating keratoplasty is the clinical gold standard. However, in cases involving compromised ocular surfaces or graft failure, osteo-odonto keratoprosthesis (OOKP) emerges as a vital yet costly and complex alternative. Thus, there is an urgent need to introduce soft biomaterials that mimic the corneal tissue, considering its translation's physicochemical, biological, and economic costs. This study introduces a cross-linked mixture of economically viable biomaterials, including gelatin, chitosan, and poly-D-lysine, that mimic corneal properties. The physicochemical evaluation of certain mixtures, specifically gelatin, chitosan, and poly-D-lysine cross-linked with 0.10% glutaraldehyde, demonstrates that properties such as swelling, optical transmittance, and thermal degradation are comparable to those of native corneas. Additionally, constructs fabricated with poly-D-lysine exhibit good cytocompatibility with fibroblasts at 72 h. These findings suggest that low-cost biopolymers, particularly those incorporating poly-D-lysine, mimic specific corneal characteristics and have the potential to foster fibroblast survival. While further studies are required to reach a final corneal-mimicking solution, this study contributes to positioning low-cost reagents as possible alternatives to develop biomaterials with physicochemical properties like those of the human cornea.

Nanocellulose-Based Hybrid Scaffolds for Skin and Bone Tissue Engineering: A 10-Year Overview

Cellulose, the most abundant polymer on Earth, has been widely utilized in its nanoform due to its excellent properties, finding applications across various scientific fields. As the demand for nanocellulose continues to rise and its ease of use becomes apparent, there has been a significant increase in research publications centered on this biomaterial. Nanocellulose, in its different forms, has shown tremendous promise as a tissue engineered scaffold for regeneration and repair. Particularly, nanocellulose-based composites and scaffolds have emerged as highly demanding materials for both soft and hard tissue engineering. Medical practitioners have traditionally relied on collagen and its analogue, gelatin, for treating tissue damage. However, the limited mechanical strength of these biopolymers restricts their direct use in various applications. This issue can be overcome by making hybrids of these biopolymers with nanocellulose. This review presents a comprehensive analysis of the recent and most relevant publications focusing on hybrid composites of collagen and gelatin with a specific emphasis on their combination with nanocellulose. While bone and skin tissue engineering represents two areas where a majority of researchers are concentrating their efforts, this review highlights the use of nanocellulose-based hybrids in these contexts.

Biofabrication paradigms in corneal regeneration: bridging bioprinting techniques, natural bioinks, and stem cell therapeutics

Corneal diseases are a major cause of vision loss worldwide. Traditional methods like corneal transplants from donors are effective but face challenges like limited donor availability and the risk of graft rejection. Therefore, new treatment methods are essential. This review examines the growing field of bioprinting and biofabrication in corneal tissue engineering. We begin by discussing various bioprinting methods such as stereolithography, inkjet, and extrusion printing, highlighting their strengths and weaknesses for eye-related uses. We also explore how biological tissues are made suitable for bioprinting through a process called decellularization, which can be achieved using chemical, physical, or biological methods. The review then looks at natural materials, known as bioinks, used in bioprinting. We focus on materials like gelatin, collagen, fibrin, chitin, chitosan, silk fibroin, and alginate, examining their mechanical and biological properties. The importance of hydrogel scaffolds, particularly those based on collagen and other materials, is also discussed in the context of repairing corneal tissue. Another key area we cover is the use of stem cells in corneal regeneration. We pay special attention to limbal epithelial stem cells and mesenchymal stromal cells, highlighting their roles in this process. The review concludes with an overview of the latest advancements in corneal tissue bioprinting, from early techniques to advanced methods of delivering stem cells using bioengineered materials. In summary, this review presents the current state and future potential of bioprinting and biofabrication in creating functional corneal tissues, highlighting new developments and ongoing challenges with a view towards restoring vision.

The Influence of Gamma Radiation on Different Gelatin Nanofibers and Gelatins

Gelatin nanofibers are known as wound-healing biomaterials due to their high biocompatible, biodegradable, and non-antigenic properties compared to synthetic-polymer-fabricated nanofibers. The influence of gamma radiation doses on the structure of gelatin nanofiber dressings compared to gelatin of their origin is little known, although it is very important for the production of stable bioactive products. Different-origin gelatins were extracted from bovine and donkey hides, rabbit skins, and fish scales and used for fabrication of nanofibers through electrospinning of gelatin solutions in acetic acid. Nanofibers with sizes ranging from 73.50 nm to 230.46 nm were successfully prepared, thus showing the potential of different-origin gelatin by-products valorization as a lower-cost alternative to native collagen. The gelatin nanofibers together with their origin gelatins were treated with 10, 20, and 25 kGy gamma radiation doses and investigated for their structural stability through chemiluminescence and FTIR spectroscopy. Chemiluminescence analysis showed a stable behavior of gelatin nanofibers and gelatins up to 200 °C and increased chemiluminescent emission intensities for nanofibers treated with gamma radiation, at temperatures above 200 °C, compared to irradiated gelatins and non-irradiated nanofibers and gelatins. The electron paramagnetic (EPR) signals of DMPO adduct allowed for the identification of long-life HO● radicals only for bovine and donkey gelatin nanofibers treated with a 20 kGy gamma radiation dose. Microbial contamination with aerobic microorganisms, yeasts, filamentous fungi, Staphylococcus aureus, Escherichia coli, and Candida albicans of gelatin nanofibers treated with 10 kGy gamma radiation was under the limits required for pharmaceutical and topic formulations. Minor shifts of FTIR bands were observed at irradiation, indicating the preservation of secondary structure and stable properties of different-origin gelatin nanofibers.