Alginate-Based Biomaterials for Regenerative Medicine Applications

An overview of magnesium-based implants in orthopaedics and a prospect of its application in spine fusion

Due to matching biomechanical properties and significant biological activity, Mg-based implants present great potential in orthopedic applications. In recent years, the biocompatibility and therapeutic effect of magnesium-based implants have been widely investigated in trauma repair. In contrast, the R&D work of Mg-based implants in spinal fusion is still limited. This review firstly introduced the general background for Mg-based implants. Secondly, the mechanical properties and degradation behaviors of Mg and its traditional and novel alloys were reviewed. Then, different surface modification techniques of Mg-based implants were described. Thirdly, this review comprehensively summarized the biological pathways of Mg degradation to promote bone formation in neuro-musculoskeletal circuit, angiogenesis with H-type vessel formation, osteogenesis with osteoblasts activation and chondrocyte ossification as an integrated system. Fourthly, this review followed the translation process of Mg-based implants via updating the preclinical studies in fracture fixation, sports trauma repair and reconstruction, and bone distraction for large bone defect. Furthermore, the pilot clinical studies were involved to demonstrate the reliable clinical safety and satisfactory bioactive effects of Mg-based implants in bone formation. Finally, this review introduced the background of spine fusion surgeryand the challenges of biological matching cage development. At last, this review prospected the translation potential of a hybrid Mg-PEEK spine fusion cage design.

Hydrogels: a promising therapeutic platform for inflammatory skin diseases treatment

Inflammatory skin diseases, such as psoriasis and atopic dermatitis, pose significant health challenges due to their long-lasting nature, potential for serious complications, and significant health risks, which requires treatments that are both effective and exhibit minimal side effects. Hydrogels offer an innovative solution due to their biocompatibility, tunability, controlled drug delivery capabilities, enhanced treatment adherence and minimized side effects risk. This review explores the mechanisms that guide the design of hydrogel therapeutic platforms from multiple perspectives, focusing on the components of hydrogels, their adjustable physical and chemical properties, and their interactions with cells and drugs to underscore their clinical potential. We also examine various therapeutic agents for psoriasis and atopic dermatitis that can be integrated into hydrogels, including traditional drugs, novel compounds targeting oxidative stress, small molecule drugs, biologics, and emerging therapies, offering insights into their mechanisms and advantages. Additionally, we review clinical trial data to evaluate the effectiveness and safety of hydrogel-based treatments in managing psoriasis and atopic dermatitis under complex disease conditions. Lastly, we discuss the current challenges and future opportunities for hydrogel therapeutics in treating psoriasis and atopic dermatitis, such as improving skin barrier penetration and developing multifunctional hydrogels, and highlight emerging opportunities to enhance long-term safety and stability.

Fabrication and Biomedical Application of Alginate Composite Hydrogels in Bone Tissue Engineering: A Review

Nowadays, as a result of the frequent occurrence of accidental injuries and traumas such as bone damage, the number of people causing bone injuries or fractures is increasing around the world. The design and fabrication of ideal bone tissue engineering (BTE) materials have become a research hotspot in the scientific community, and thus provide a novel path for the treatment of bone diseases. Among the materials used to construct scaffolds in BTE, including metals, bioceramics, bioglasses, biomacromolecules, synthetic organic polymers, etc., natural biopolymers have more advantages against them because they can interact with cells well, causing natural polymers to be widely studied and applied in the field of BTE. In particular, alginate has the advantages of excellent biocompatibility, good biodegradability, non-immunogenicity, non-toxicity, wide sources, low price, and easy gelation, enabling itself to be widely used as a biomaterial. However, pure alginate hydrogel as a BTE scaffold material still has many shortcomings, such as insufficient mechanical properties, easy disintegration of materials in physiological environments, and lack of cell-specific recognition sites, which severely limits its clinical application in BTE. In order to overcome the defects of single alginate hydrogels, researchers prepared alginate composite hydrogels by adding one or more materials to the alginate matrix in a certain proportion to improve their bioapplicability. For this reason, this review will introduce in detail the methods for constructing alginate composite hydrogels, including alginate/polymer composite hydrogels, alginate/bioprotein or polypeptide composite hydrogels, alginate/bioceramic composite hydrogels, alginate/bioceramic composite hydrogels, and alginate/nanoclay composite hydrogels, as well as their biological application trends in BTE scaffold materials, and look forward to their future research direction. These alginate composite hydrogel scaffolds exhibit both unexceptionable mechanical and biochemical properties, which exhibit their high application value in bone tissue repair and regeneration, thus providing a theoretical basis for the development and sustainable application of alginate-based functional biomedical materials.

A functional mineralized collagen hydrogel to promote angiogenic and osteogenic for osseointegration of 3D-printed titanium alloy microporous scaffolds

Bone defects, resulting from trauma, inflammation, tumors, and various other factors, affect both health and quality of life. Although autologous bone transplantation is the gold-standard treatment for bone defects, it has disadvantages such as donor site limitations, prolonged surgical durations, and potential complications, necessitating the development of alternative bone tissue engineering materials. In this study, we used 3D printing technology to fabricate porous titanium implants characterized by superior biocompatibility and mechanical properties. Sodium alginate (SA) and strontium ions (Sr2+) were integrated into mineralized collagen matrices (MCs) to develop strontium-functionalized alginate-mineralized collagen hydrogels (SAMs) with high mechanical strength and sustained metal ion release ability. SAMs were seamlessly incorporated into the porous structures of 3D-printed titanium scaffolds, establishing a novel organic-inorganic bioactive interface. This composite system exhibited high biocompatibility in vitro and increased the expression of genes important for osteogenic differentiation and angiogenesis. In a rabbit model of femoral defect, the titanium implants effectively promoted bone and vascular regeneration on their surface, highlighting their potential in facilitating bone-implant integration.

Navigating the challenges and exploring the perspectives associated with emerging novel biomaterials

The field of biomaterials is a continuously evolving interdisciplinary field encompassing biological sciences, materials sciences, chemical sciences, and physical sciences with a multitude of applications realized every year. However, different biomaterials developed for different applications have unique challenges in the form of biological barriers, and addressing these challenges simultaneously is also a challenge. Nevertheless, immense progress has been made through the development of novel materials with minimal adverse effects such as DNA nanostructures, specific synthesis strategies based on supramolecular chemistry, and modulating the shortcomings of existing biomaterials through effective functionalization techniques. This review discusses all these aspects of biomaterials, including the challenges at each level of their development and application, proposed countermeasures for these challenges, and some future directions that may have potential benefits.

Heat-treated alginate-polycaprolactone core-shell nanofibers by emulsion electrospinning process for biomedical applications

Fabrication of Core-shell nanofibrous mat which is a promising tool for a wide range of applications in tissue engineering can be developed using water in oil (W/O) or oil in water (O/W) emulsion electrospinning. In this study, for the first time, we fabricated an O/W emulsion-based electrospun core-shell mat using polycaprolactone (PCL) as a core and the blend solution of alginate (Alg) and polyethylene oxide (PEO) as shell material. To achieve a stable core-shell mat, firstly, Alg was modified with heat treatment to decrease the molecular weight of Alg. Then, to improve the chain flexibility of Alg, PEO as a second polymer was added to facilitate its electrospinnability. The different volume ratios of O/W were then fabricated by adding PCL to the Alg-PEO solution to find an optimized emulsion solution. The morphology, swelling, and porosity of the construct were evaluated. At the same time, the mechanical characteristic of fibers was evaluated in both dry and wet conditions. This study also examined cell-scaffold interactions to address the need for a scaffolding material to be suitable for tissue engineering and biomedical applications. Finally, the result exhibited a distinct core-shell structure with better mechanical properties compared to the Alg-PEO.

Drug delivery using reduction-responsive hydrogel based on carboxyethyl-succinoglycan with highly improved rheological, antibacterial, and antioxidant properties

The development of exopolysaccharide-based polymers is gaining increasing attention in various industrial biotechnology fields for materials such as thickeners, texture modifiers, anti-freeze agents, antioxidants, and antibacterial agents. High-viscosity carboxyethyl-succinoglycan (CE-SG) was directly synthesized from succinoglycan (SG) isolated from Sinorhizobium meliloti Rm 1021, and its structural, rheological, and physiological properties were investigated. The viscosity of CE-SG gradually increased in proportion to the degree of carboxyethylation substitution. In particular, when the molar ratio of SG and 3-chloropropionic acid was 1:100, the viscosity was significantly improved by 21.18 times at a shear rate of 10 s-1. Increased carboxyethylation of SG also improved the thermal stability of CE-SG. Furthermore, the CE-SG solution showed 90.18 and 91.78 % antibacterial effects against Escherichia coli and Staphylococcus aureus and effective antioxidant activity against DPPH and hydroxyl radicals. In particular, CE-SG hydrogels coordinated with Fe3+ ions, which improved both viscosity and rheological properties, while also exhibiting reduction-responsive drug release through 1,4-dithiothreitol. The results of this study suggest that SG derivatives, such as CE-SG, can be used as functional biomaterials in various fields such as food, cosmetics, and pharmaceutical industries.

Alginate-Chitosan Biodegradable and Biocompatible Based Hydrogel for Breast Cancer Immunotherapy and Diagnosis: A Comprehensive Review

Breast cancer is the most common type of cancer and the second leading cause of cancer-related mortality in females. There are many side effects due to chemotherapy and traditional surgery, like fatigue, loss of appetite, skin irritation, and drug resistance to cancer cells. Immunotherapy has become a hopeful approach toward cancer treatment, generating long-lasting immune responses in malignant tumor patients. Recently, hydrogel has received more attention toward cancer therapy due to its specific characteristics, such as decreased toxicity, fewer side effects, and better biocompatibility drug delivery to the particular tumor location. Researchers globally reported various investigations on hydrogel research for tumor diagnosis. The hydrogel-based multilayer platform with controlled nanostructure has received more attention for its antitumor effect. Chitosan and alginate play a leading role in the formation of the cross-link in a hydrogel. Also, they help in the stability of the hydrogel. This review discusses the properties, preparation, biocompatibility, and bioavailability of various research and clinical approaches of the multipolymer hydrogel made of alginate and chitosan for breast cancer treatment. With a focus on cases of breast cancer and the recovery rate, there is a need to find out the role of hydrogel in drug delivery for breast cancer treatment.

An ultrasound-triggered injectable sodium alginate scaffold loaded with electrospun microspheres for on-demand drug delivery to accelerate bone defect regeneration

Biological processes, such as bone defects healing are precisely controlled in both time and space. This spatiotemporal characteristic inspires novel therapeutic strategies. The sustained-release systems including hydrogels are commonly utilized in the treatment of bone defect; however, traditional hydrogels often release drugs at a consistent rate, lacking temporal precision. In this study, a hybrid hydrogel has been developed by using sodium alginate, sucrose acetate isobutyrate, and electrospray microspheres as the base materials, and designed with ultrasound response, and on-demand release properties. Sucrose acetate isobutyrate was added to the hybrid hydrogel to prevent burst release. The network structure of the hybrid hydrogel is formed by the interconnection of Ca2+ with the carboxyl groups of sodium alginate. Notably, when the hybrid hydrogel is exposed to ultrasound, the ionic bond can be broken to promote drug release; when ultrasound is turned off, the release returned to a low-release state. This hybrid hydrogel reveals not only injectability, degradability, and good mechanical properties but also shows multiple responses to ultrasound. And it has good biocompatibility and promotes osteogenesis efficiency in vivo. Thus, this hybrid hydrogel provides a promising therapeutic strategy for the treatment of bone defects.

Recent Advances in Environmentally Friendly Dual-crosslinking Polymer Networks

Environmentally friendly crosslinked polymer networks feature degradable covalent or non-covalent bonds, with many of them manifesting dynamic characteristics. These attributes enable convenient degradation, facile reprocessibility, and self-healing capabilities. However, the inherent instability of these crosslinking bonds often compromises the mechanical properties of polymer networks, limiting their practical applications. In this context, environmentally friendly dual-crosslinking polymer networks (denoted EF-DCPNs) have emerged as promising alternatives to address this challenge. These materials effectively balance the need for high mechanical properties with the ability to degrade, recycle, and/or self-heal. Despite their promising potential, investigations into EF-DCPNs remain in their nascent stages, and several gaps and limitations persist. This Review provides a comprehensive overview of the synthesis, properties, and applications of recent progress in EF-DCPNs. Firstly, synthetic routes to a rich variety of EF-DCPNs possessing two distinct types of dynamic bonds (i.e., imine, disulfide, ester, hydrogen bond, coordination bond, and other bonds) are introduced. Subsequently, complex structure- and dynamic nature-dependent mechanical, thermal, and electrical properties of EF-DCPNs are discussed, followed by their exemplary applications in electronics and biotechnology. Finally, future research directions in this rapidly evolving field are outlined.

Facile synthesis of double-cross-linked alginate-based hydrogel: Characterization and use in a context of circular economy for cationic dye removal

Hydrogels based on natural polysaccharides have received special attention in the last decade due to their interesting features, such as availability, biocompatibility, biodegradability and safety. Such characteristics may make them sustainable and eco-friendly materials for water and wastewater treatment, meeting the concept of circular economy. In this study, a novel double-cross-linked alginate-based hydrogel has been successfully synthesized using epichlorhydrin and sodium trimetaphosphate (STMP) as cross-linker agents and then used for the removal of methylene blue (MB) dye under different operating conditions. The obtained hydrogel was deeply characterized by using various analytical techniques, namely Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and differential scanning calorimetry. Experimental results showed that the synthesized double cross-linked hydrogel with relatively high STMP concentration (0.26 M) has promising structural and textural properties. This material exhibited excellent removal ability towards MB with a maximum adsorption capacity of about 992 mg/g for an initial pH of 10. The kinetic and isotherm modeling study revealed that the pseudo-second-order and Freundlich models fitted well the measured adsorption experimental data. The MB adsorption process onto the synthesized hydrogel is exothermic, feasible and spontaneous. It mainly includes electrostatic interaction and hydrogen bonds. These findings suggest that double-cross-linked alginate-based hydrogel can be considered as an attractive and potential adsorbent for an effective cationic dye removal from aqueous environments. The use of such a green adsorbent for the treatment of organic-pollutants-rich industrial wastewaters promotes sustainability and circular economy concepts.

Biomimetic Scaffolds for Regeneration of Temporomandibular Joint Disc: A Narrative Review

Defects and dysfunctions of temporomandibular joint (TMJ) disc are responsible for the majority of TMJ diseases. Current treatments in this matter are usually short-term and only palliative, thus an alternative treatment that offers long-lasting repair is in great demand. In recent years great attempts have been made to prepare an ideal scaffold, which best resembles the native TMJ disc in characteristics such as mechanical, physical and biological properties. This narrative review focuses on developments of the recent ten years in fabrication of scaffolds using decellularized tissues, natural and synthetic biomaterials for regeneration of TMJ disc and compared their properties. PubMed and Google Scholar databases were searched using the following keywords ("TMJ" OR "temporomandibular joint" OR "TMD" OR "temporomandibular disease") AND ("scaffold" OR "hydrogels"). Randomized controlled trials, randomized clinical trials, case-controls, case reports, and animal studies were included. Comments, systematic reviews, meta-analyses, and non-English papers were excluded. The study concluded that hybrid scaffolds have exhibited favorable cell attachment and proliferation. Synthetic scaffolds have shown promise in providing better control over structural properties; however, additional processes are often required to provide biomimetic cell signaling. While there is still much to learn about the ideal scaffold for TMJ disc regeneration, both natural and synthetic scaffolds have shown promise in achieving the functional, structural, biological, and mechanical properties of a native TMJ disc.

3D Printing of Polysaccharide-Based Hydrogel Scaffolds for Tissue Engineering Applications: A Review

In tissue engineering, 3D printing represents a versatile technology employing inks to construct three-dimensional living structures, mimicking natural biological systems. This technology efficiently translates digital blueprints into highly reproducible 3D objects. Recent advances have expanded 3D printing applications, allowing for the fabrication of diverse anatomical components, including engineered functional tissues and organs. The development of printable inks, which incorporate macromolecules, enzymes, cells, and growth factors, is advancing with the aim of restoring damaged tissues and organs. Polysaccharides, recognized for their intrinsic resemblance to components of the extracellular matrix have garnered significant attention in the field of tissue engineering. This review explores diverse 3D printing techniques, outlining distinctive features that should characterize scaffolds used as ideal matrices in tissue engineering. A detailed investigation into the properties and roles of polysaccharides in tissue engineering is highlighted. The review also culminates in a profound exploration of 3D polysaccharide-based hydrogel applications, focusing on recent breakthroughs in regenerating different tissues such as skin, bone, cartilage, heart, nerve, vasculature, and skeletal muscle. It further addresses challenges and prospective directions in 3D printing hydrogels based on polysaccharides, paving the way for innovative research to fabricate functional tissues, enhancing patient care, and improving quality of life.

Towards Stem Cell Therapy for Critical-Sized Segmental Bone Defects: Current Trends and Challenges on the Path to Clinical Translation

The management and reconstruction of critical-sized segmental bone defects remain a major clinical challenge for orthopaedic clinicians and surgeons. In particular, regenerative medicine approaches that involve incorporating stem cells within tissue engineering scaffolds have great promise for fracture management. This narrative review focuses on the primary components of bone tissue engineering-stem cells, scaffolds, the microenvironment, and vascularisation-addressing current advances and translational and regulatory challenges in the current landscape of stem cell therapy for critical-sized bone defects. To comprehensively explore this research area and offer insights for future treatment options in orthopaedic surgery, we have examined the latest developments and advancements in bone tissue engineering, focusing on those of clinical relevance in recent years. Finally, we present a forward-looking perspective on using stem cells in bone tissue engineering for critical-sized segmental bone defects.

How Biodegradable Polymers Can be Effective Drug Delivery Systems for Cannabinoids? Prospectives and Challenges

Cannabinoids are compounds found in and derived from the Cannabis plants that have become increasingly recognised as significant modulating factors of physiological mechanisms and inflammatory reactions of the organism, thus inevitably affecting maintenance of homeostasis. Medical Cannabis popularity has surged since its legal regulation growing around the world. Numerous promising discoveries bring more data on cannabinoids' pharmacological characteristics and therapeutic applications. Given the current surge in interest in the medical use of cannabinoids, there is an urgent need for an effective method of their administration. Surpassing low bioavailability, low water solubility, and instability became an important milestone in the advancement of cannabinoids in pharmaceutical applications. The numerous uses of cannabinoids in clinical practice remain restricted by limited administration alternatives, but there is hope when biodegradable polymers are taken into account. The primary objective of this review is to highlight the wide range of indications for which cannabinoids may be used, as well as the polymeric carriers that enhance their effectiveness. The current review described a wide range of therapeutic applications of cannabinoids, including pain management, neurological and sleep disorders, anxiety, and cancer treatment. The use of these compounds was further examined in the area of dermatology and cosmetology. Finally, with the use of biodegradable polymer-based drug delivery systems (DDSs), it was demonstrated that cannabinoids can be delivered specifically to the intended site while also improving the drug's physicochemical properties, emphasizing their utility. Nevertheless, additional clinical trials on novel cannabinoids' formulations are required, as their full spectrum therapeutical potential is yet to be unravelled.

Hydrogel Formulation for Biomimetic Fibroblast Cell Culture: Exploring Effects of External Stresses and Cellular Responses

In the process of tissue engineering, several types of stresses can influence the outcome of tissue regeneration. This outcome can be understood by designing hydrogels that mimic this process and studying how such hydrogel scaffolds and cells behave under a set of stresses. Here, a hydrogel formulation is proposed to create biomimetic scaffolds suitable for fibroblast cell culture. Subsequently, we examine the impact of external stresses on fibroblast cells cultured on both solid and porous hydrogels. These stresses included mechanical tension and altered-gravity conditions experienced during the 83rd parabolic flight campaign conducted by the European Space Agency. This study shows distinct cellular responses characterized by cell aggregation and redistribution in regions of intensified stress concentration. This paper presents a new biomimetic hydrogel that fulfills tissue-engineering requirements in terms of biocompatibility and mechanical stability. Moreover, it contributes to our comprehension of cellular biomechanics under diverse gravitational conditions, shedding light on the dynamic cellular adaptations versus varying stress environments.

Prospects and challenges for the application of tissue engineering technologies in the treatment of bone infections

Osteomyelitis is a devastating disease caused by microbial infection in deep bone tissue. Its high recurrence rate and impaired restoration of bone deficiencies are major challenges in treatment. Microbes have evolved numerous mechanisms to effectively evade host intrinsic and adaptive immune attacks to persistently localize in the host, such as drug-resistant bacteria, biofilms, persister cells, intracellular bacteria, and small colony variants (SCVs). Moreover, microbial-mediated dysregulation of the bone immune microenvironment impedes the bone regeneration process, leading to impaired bone defect repair. Despite advances in surgical strategies and drug applications for the treatment of bone infections within the last decade, challenges remain in clinical management. The development and application of tissue engineering materials have provided new strategies for the treatment of bone infections, but a comprehensive review of their research progress is lacking. This review discusses the critical pathogenic mechanisms of microbes in the skeletal system and their immunomodulatory effects on bone regeneration, and highlights the prospects and challenges for the application of tissue engineering technologies in the treatment of bone infections. It will inform the development and translation of antimicrobial and bone repair tissue engineering materials for the management of bone infections.

Advanced Immunomodulatory Biomaterials for Therapeutic Applications

The multifaceted biological defense system modulating complex immune responses against pathogens and foreign materials plays a critical role in tissue homeostasis and disease progression. Recently developed biomaterials that can specifically regulate immune responses, nanoparticles, graphene, and functional hydrogels have contributed to the advancement of tissue engineering as well as disease treatment. The interaction between innate and adaptive immunity, collectively determining immune responses, can be regulated by mechanobiological recognition and adaptation of immune cells to the extracellular microenvironment. Therefore, applying immunomodulation to tissue regeneration and cancer therapy involves manipulating the properties of biomaterials by tailoring their composition in the context of the immune system. This review provides a comprehensive overview of how the physicochemical attributes of biomaterials determine immune responses, focusing on the physical properties that influence innate and adaptive immunity. This review also underscores the critical aspect of biomaterial-based immune engineering for the development of novel therapeutics and emphasizes the importance of understanding the biomaterials-mediated immunological mechanisms and their role in modulating the immune system.

Development and Evaluation of Alginate- and Carrageenan-Incorporated Scaffold for Bone Regeneration: An In Vitro Study

INTRODUCTION

Periodontitis, a persistent inflammatory condition, results in the deterioration of both the hard and soft tissues in the periodontium, leading to the formation of intrabony defects. Restoring the lost tissues, particularly bone, is possible through tissue engineering techniques utilizing scaffolds made from different polymers. Consequently, this research focuses on creating and assessing a scaffold infused with alginate (Sigma Aldrich, Gillingham, UK) and carrageenan (Sigma Aldrich, Gillingham, UK) for the purpose of bone regeneration.

METHODS

An in vitro investigation was conducted to assess the characteristics of the recently formulated scaffold. Spectroscopic analysis, tensile strength testing, scanning electron microscopy (SEM) analysis, and degradation testing were carried out to evaluate both the physical and biological attributes of the scaffold.

RESULTS

IBM SPSS Statistics for Windows, V. 1.2 (IBM Corp., Armonk, NY, USA) was used for statistical analysis. A one-way ANOVA test was done to determine the significance of tensile strength, and a paired t-test was done to check the significance of the degradation test. The in vitro research unveiled notable distinctions in the physical and biological attributes between the scaffold infused with alginate and carrageenan and the PerioCol® (p<0.05).

CONCLUSION

The scaffold incorporating alginate and carrageenan demonstrated superior outcomes concerning parameters such as tensile stress and strain, degradation rate, percentage bone volume, and object surface density when contrasted with the conventional PerioCol®. Therefore, the scaffold infused with alginate and carrageenan emerges as a promising candidate for bone regeneration.

Simulation clinic waste audit assessment and recommendations at the University of Washington School of Dentistry

OBJECTIVE

Dentistry produces waste contributing to climate change and adverse health outcomes, thus reducing waste is essential; however, there has been minimal emphasis on sustainability or climate action in dentistry. Waste audits quantify the type and amount of waste produced and may inform waste reduction strategies. We conducted a waste audit to identify areas of potential waste reduction and recommend interventions to reduce waste.

METHODS

In this cross-sectional study, we conducted a waste audit of garbage produced during a typical 4-hour pre-clinical restorative dentistry simulation exercise. The sample was composed of 72 second-year dental students. This exercise is part of a standard curriculum with a uniform format regarding supplies used and participants. Potentially infectious materials were not used during this exercise.

RESULTS

In total, 26.6 kg of waste was discarded. Plastic was the largest contributor by mass (57.5%), followed by paper barriers (19.6%), then impression materials (6.5%). We found 894 gloves and 70 masks discarded.

CONCLUSIONS

Based on these findings, we categorized waste reduction opportunities into policy changes, purchasing sustainable materials, and increasing awareness through education. Specific suggested actions include: relaxing glove and gown requirements during laboratory simulations; replacing single use items with more sustainable options; increasing use of intraoral scanners; and posting informational signage with examples of what can be recycled.

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.

Preparation, evaluation and application of MRI detectable sunitinib-loaded calcium alginate/poly(acrylic acid) hydrogel microspheres

Transcatheter arterial chemoembolization (TACE) is an effective method for the treatment of unresectable hepatocellular carcinoma. Although many embolic agents have been developed in TACE, there are few ideal embolic agents that combine drug loading, imaging properties and vessel embolization. Here, we developed novel magnetic embolic microspheres that could simultaneously load sunitinib malate (SU), be detected by magnetic resonance imaging (MRI) and block blood vessels. Calcium alginate/poly (acrylic acid) hydrogel microspheres (CA/PAA-MDMs) with superparamagnetic iron oxide nanoparticles (SPIONs) modified by citric acid were prepared by a drip and photopolymerization method. The embolization and imaging properties of CA/PAA-MDMs were evaluated through a series of experiments such as morphology, X-ray diffraction and X-ray photoelectron spectroscopy, magnetic responsiveness analysis, elasticity, cytotoxicity, hemolysis test, in vitro MRI evaluation, rabbit ear embolization and histopathology. In addition, the ability of drug loading and drug release of CA/PAA-MDMs were investigated by using sunitinib (SU) as the model drug. In conclusion, CA/PAA-MDMs showed outstanding drug loading capability, excellent imaging property and embolization effect, which would be expected to be used as a potential biodegradable embolic agent in the clinical interventional therapy.

Dextrans, Pullulan and Lentinan, New Scaffold Materials for Use as Hydrogels in Tissue Engineering

The development of hydrogels based on dextrans, pullulan and lentinan to be used in biomedical applications including tissue engineering is reported. Despite the fact that selected polysaccharides such as hyaluronic acid are well established, little is known, how these polysaccharides can be chemically modified to create hydrogels under controlled conditions. In this study we present a small library of chemically modified polysaccharides which are used for a divergent approach to achieve biomedical relevant hydrogels. In this case the crosslinking is based on thio ether formation between thiol modified donor and vinylsulfone or maleimide modified acceptor components. Successful synthesis of the linker systems and coupling at the polysaccharides, hydrogel formation takes place under physiological conditions. We extended the study by coupling small molecules like adhesion factors for increasing cell compatibility as well as a dye for further studies. The different hydrogels were studied to their rheological properties, water uptake, their permeability, biodegrability and their cytotoxicity.

Visualizing the global trends of peptides in wound healing through an in-depth bibliometric analysis

Wound healing is a complicated and multistage biological process for the repair of damaged/injured tissues, which requires intelligent designs to provide comprehensive and convenient treatment. Peptide-based wound dressings have received extensive attention for further development and application due to their excellent biocompatibility and multifunctionality. However, the current lack of intuitive analysis of the development trend and research hotspots of peptides applied in wound healing, as well as detailed elaboration of possible research hotspots, restricted obtaining a comprehensive understanding and development in this field. The present study analysed publications from the Web of Science (WOS) Core Collection database and visualized the hotspots and current trends of peptide research in wound healing. Data between January 1st, 2003, and December 31st, 2022, were collected and subjected to a bibliometric analysis. The countries, institutions, co-authorship, co-citation reference, and co-occurrence of keywords in this subject were examined using VOSviewer and CiteSpace. We provided an intuitive, timely, and logical overview of the development prospects and challenges of peptide application in wound healing and some solutions to the major obstacles, which will help researchers gain insights into the investigation of this promising field.

Assessing the efficacy of curcumin-loaded alginate hydrogel on skin wound healing: A gene expression analysis

Skin tissue engineering has gained significant attention as a promising alternative to traditional treatments for skin injuries. In this study, we developed 3D hydrogel-based scaffolds, Alginate, incorporating different concentrations of Curcumin and evaluated their properties, including morphology, swelling behavior, weight loss, as well as hemo- and cytocompatibility. Furthermore, we investigated the therapeutic potential of Alginate hydrogel containing different amounts of Curcumin using an in vitro wound healing model. The prepared hydrogels exhibited remarkable characteristics, SEM showed that the pore size of hydrogels was 134.64 μm with interconnected pores, making it conducive for cellular infiltration and nutrient exchange. Moreover, hydrogels demonstrated excellent biodegradability, losing 63.5% of its weight over 14 days. In addition, the prepared hydrogels had a stable release of curcumin for 3 days. The results also show the hemocompatibility of prepared hydrogels and a low amount of blood clotting. To assess the efficacy of the developed hydrogels, 3T3 fibroblast growth was examined during various incubation times. The results indicated that the inclusion of Curcumin at a concentration of 0.1 mg/mL positively influenced cellular behavior. The animal study showed that Alginate hydrogel containing 0.1 mg/mL curcumin had high wound closure(more than 80%) after 14 days. In addition, it showed up-regulation of essential wound healing genes, including TGFβ1 and VEGF, promoting tissue repair and angiogenesis. Furthermore, the treated group exhibited down-regulation of MMP9 gene expression, indicating a reduction in matrix degradation and inflammation. The observed cellular responses and gene expression changes substantiate the therapeutic efficacy of prepared hydrogels. Consequently, our study showed the healing effect of alginate-based hydrogel containing Curcumin on skin injuries.

Microencapsulate Probiotics (MP) Promote Growth Performance and Inhibit Inflammatory Response in Broilers Challenged with Salmonella typhimurium

Antibiotic-resistant bacteria are prevalent in husbandry around the world due to the abuse of antibiotic growth promoters (AGPs); therefore, it is necessary to find alternatives to AGPs in animal feed. Among all the candidates, probiotics are promising alternatives to AGPs against Salmonella infection. The anti-Salmonella effects of three probiotic strains, namely, Lactobacillus crispatus 7-4, Lactobacillus johnsonii 3-1, and Pediococcus acidilactici 20-1, have been demonstrated in our previous study. In this study, we further obtained the alginate beads containing compound probiotics, namely, microencapsulate probiotics (MP), and evaluated its regulatory effect on the health of broilers. We incubated free and microencapsulate probiotics in simulated gastric and intestinal juice for 2 h, and the results showed that compared to free probiotics, encapsulation increased tolerance of compound probiotics in the simulated gastrointestinal condition. We observed that the application of probiotics, especially MP, conferred protective effects against Salmonella typhimurium (S.Tm) infection in broilers. Compared to the S.Tm group, the MP could promote the growth performance (p < 0.05) and reduce the S.Tm load in intestine and liver (p < 0.05). In detail, MP pretreatment could modulate the cecal microflora and upregulate the relative abundance of Lactobacillus and Enterobacteriaceae. Besides, MP could reduce the inflammation injury of the intestine and liver, reduce the pro-inflammatory cytokines (IL-6, TNF-α, IL-1β) expression, and induce of anti-inflammatory cytokine (IL-10) expression. Furthermore, MP could inhibit NLRP3 pathway in ileum, thereby attenuating S.Tm-induced inflammation. In conclusion, MP could be a new feeding supplementation strategy to substitute AGPs in poultry feeding.

Kappa-carrageenan and sodium alginate-based pH-responsive hydrogels for controlled release of methotrexate

Despite remarkable progress in medical sciences, modern man is still fighting the battle against cancer. In 2022, only in the USA, 640 000 deaths and 2 370 000 patients were reported because of cancer. Chemotherapy is the most widely used for cancer treatments. However, chemotherapeutics have severe physicochemical side effects. Therefore, we have prepared poly(amididoamine) dendrimeric carrageenan (CG), sodium alginate (SA) and poly(vinyl alcohol) (PVA) hydrogels by using solution casting methodology. The constituents of hydrogels were cross-linked by mutable quantity of 3-aminopropyl(diethoxy)methyl silane (APDMS). Hydrogels were characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscope and atomic force microscopy. Hydrogels exhibited higher swelling volumes in 5-7 pH range. In vitro biodegradation in ribonuclease-A solution and cytocompatibility analysis against DF-1 fibroblasts established their biodegradable and non-toxic nature, which enables them as a suitable carrier for chemotherapeutic compounds. Hence, methotrexate (MTX) as a model drug was loaded on CAP-8 hydrogel and its release was detected by the UV-visible spectrophotometer in phosphate-buffered saline (PBS) solution. In 13.5 h, 81.25% and 77.23% of MTX were released at pH 7.4 (blood pH) and 5.3 (tumour pH) in PBS, respectively. MTX was released by super case II mechanism and best fitted to zero-order and Korsmeyer-Peppas model. The synthesized APDMS cross-linked CG/SA/PVA dendrimeric hydrogels could be an efficient model platform for the effective delivery of MTX in cancer treatments.

Injectable pathological microenvironment-responsive anti-inflammatory hydrogels for ameliorating intervertebral disc degeneration

Chronic local inflammation and resulting cellular dysfunction of nucleus pulposus (NP) cells are important pathogenic factors of intervertebral disc degeneration (IDD). Injectable pathological microenvironment-responsive hydrogels hold significant potential for treating IDD by adapting to dynamic microenvironment of IDD. Herein, we proposed an injectable gelatin-based hydrogel drug delivery system that could respond to the pathological microenvironment of IDD for controlled release of anti-inflammatory drug to promote degenerative NP repair. The hydrogel system was prepared by conjugating phenylboronic acid-modified gelatin methacryloyl (GP) with the naturally extracted anti-inflammatory drug epigallocatechin-3-gallate (EGCG) through dynamic boronic esters. The hydrogel exhibited excellent degradability, injectability, antioxidant properties, anti-inflammatory effects, and biocompatibility. It also displayed responsive-release of EGCG under high reactive oxygen species (ROS) levels and acidic conditions. The hydrogel demonstrated remarkable cytoprotective effects on NP cells in both hyperactive ROS environments and inflammatory cytokine-overexpressed environments in vitro. In vivo studies revealed that the hydrogel injected in situ could effectively ameliorate the intervertebral disc degeneration by maintaining the disc height and NP tissue structure in a rat IDD model. The hydrogel system exhibited excellent biocompatibility and responsive-release of diol-containing drugs in pathological microenvironments, indicating its potential application as a drug delivery platform.

Layer-by-layer assembly of chitosan/alginate thin films containing Salmonella enterica bacteriophages for antibacterial applications

The emergence of antibiotic resistant bacteria and the ineffectiveness of routine treatments inspired development of alternatives to biocides for antibacterial applications. Bacteriophages are natural predators of bacteria and are promising alternatives to antibiotics. This study presents fabrication of a Salmonella enterica bacteriophage containing ultra-thin multilayer film composed of chitosan and alginate and demonstrates its potential as an antibacterial coating for food packaging applications. Chitosan/alginate film was prepared through layer-by-layer (LbL) self-assembly technique. A bacteriophage, which belongs to Siphoviridae morphotype (MET P1-001_43) and infects Salmonella enterica subsp. enterica serovar Enteritidis (Salmonella Enteritidis), was post-loaded into chitosan/alginate film. The LbL growth, stability, and surface morphology of chitosan/alginate film as well as phage deposition into multilayers were analysed through ellipsometry, QCM-D and AFM techniques. The bacteriophage containing multilayers showed antibacterial activity at pH 7.0. In contrast, anti-bacterial activity was not observed at acidic conditions. We showed that wrapping a Salmonella Enteritidis contaminated chicken piece with aluminium foil whose surface was modified with phage loaded chitosan/alginate multilayers decreased the number of colonies on the chicken meat, and it was as effective as treating the meat directly with phage solution.

Trends in bioactivity: inducing and detecting mineralization of regenerative polymeric scaffolds

Due to limitations of biological and alloplastic grafts, regenerative engineering has emerged as a promising alternative to treat bone defects. Bioactive polymeric scaffolds are an integral part of such an approach. Bioactivity importantly induces hydroxyapatite mineralization that promotes osteoinductivity and osseointegration with surrounding bone tissue. Strategies to confer bioactivity to polymeric scaffolds utilize bioceramic fillers, coatings and surface treatments, and additives. These approaches can also favorably impact mechanical and degradation properties. A variety of fabrication methods are utilized to prepare scaffolds with requisite morphological features. The bioactivity of scaffolds may be evaluated with a broad set of techniques, including in vitro (acellular and cellular) and in vivo methods. Herein, we highlight contemporary and emerging approaches to prepare and assess scaffold bioactivity, as well as existing challenges.

Research Progress on Injectable Microspheres as New Strategies for the Treatment of Osteoarthritis Through Promotion of Cartilage Repair

Osteoarthritis (OA) is a degenerative disease caused by a variety of factors with joint pain as the main symptom, including fibrosis, chapping, ulcers, and loss of cartilage. Traditional treatment can only delay the progression of OA, and classical delivery system have many side effects. In recent years, microspheres have shown great application prospects in the field of OA treatment. Microspheres can support cells, reproduce the natural tissue microenvironment in vitro and in vivo, and are an efficient delivery system for the release of drugs or biological agents, which can promote cell proliferation, migration, and differentiation. Thus, they have been widely used in cartilage repair and regeneration. In this review, preparation processes, basic materials, and functional characteristics of various microspheres commonly used in OA treatment are systematically reviewed. Then it is introduced surface modification strategies that can improve the biological properties of microspheres and discussed a series of applications of microsphere functionalized scaffolds in OA treatment. Finally, based on bibliometrics research, the research development, future potential, and possible research hotspots of microspheres in the field of OA therapy is systematically and dynamically evaluated. The comprehensive and systematic review will bring new understanding to the field of microsphere treatment of OA.

In-situ magnetic alginate coated chitosan core@shell beads with excellent performance in simulated and real wastewater treatment: Behavior, mechanisms, and new perspectives

Herein, a new hybrid magnetic core@shell biocomposite was prepared based on an alginate-bentonite core and a chitosan shell layer (mAB@Cs) where magnetic Fe3O4 NPs (50.7 nm) were in-situ generated on the surface via a simple non-thermal co-precipitation approach. The biocomposite has a high ability to magnetically separate and remove organic (ciprofloxacin (CPX)) and seven toxic inorganic (Cu2+, Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Hg2+) contaminants from simulated wastewater. Experimental results showed a CPX monolayer chemisorption with a Langmuir maximum adsorption capacity of 264.7 mg/g, maintained effectiveness up to the fifth cycle, and high removal rates of heavy metals ranging from 74.89 % to 99.86 % corresponding to adsorption capacities ranging from 12 to 20 mg/g. For a more accurate evaluation, the biocomposite was tested on a real urban wastewater sample (RWW) and it has manifested a noteworthy efficiency in removing a mixture of inorganic pollutants in terms of potassium K+ and orthophosphate phosphorous P-PO43-, and organic matter in terms of biological oxygen demand (BOD) and chemical oxygen demand (COD) with 46 %, 90 %, 84 %, and 64 % removal efficiencies, respectively. On top of this, a high inactivation rate of E. coli of the order of 96 % was recorded, making the prepared magnetic biocomposite adept for the simultaneous removal of emergent wastewater pollutants, from organic, inorganic, to pathogen microorganisms.

The potential of graphene coatings as neural interfaces

Recent advances in nanotechnology design and fabrication have shaped the landscape for the development of ideal cell interfaces based on biomaterials. A holistic evaluation of the requirements for a cell interface is a highly complex task. Biocompatibility is a crucial requirement which is affected by the interface's properties, including elemental composition, morphology, and surface chemistry. This review explores the current state-of-the-art on graphene coatings produced by chemical vapor deposition (CVD) and applied as neural interfaces, detailing the key properties required to design an interface capable of physiologically interacting with neural cells. The interfaces are classified into substrates and scaffolds to differentiate the planar and three-dimensional environments where the cells can adhere and proliferate. The role of specific features such as mechanical properties, porosity and wettability are investigated. We further report on the specific brain-interface applications where CVD graphene paved the way to revolutionary advances in biomedicine. Future studies on the long-term effects of graphene-based materials in vivo will unlock even more potentially disruptive neuro-applications.

Influence of biopolymer composition and crosslinking agent concentration on the micro- and nanomechanical properties of hydrogel-based filaments

Hydrogel filaments were manufactured using wet spinning technique, incorporating variations in the concentrations of sodium alginate, gelatin, and calcium chloride (crosslinking agent). The combination of biopolymer concentrations was determined using design of experiments (DoE) approach. The resulting filaments were produced from the developed hydrogels. Tensile and vertical strength analyses of the filaments were conducted using an electromechanical extensor. Atomic force microscopy was employed to evaluate the roughness, viscoelasticity, retraction, and deflection of the hydrogels. By employing DoE, a total of seventeen different combinations of biopolymers and crosslinkers were generated to construct the hydrogels. The filaments exhibited variations in electromechanical traction (measured in kPa) and produced distinct stress peaks. Furthermore, diverse roughness values were observed among the tested materials, with the combinations featuring higher concentrations of sodium alginate displaying the highest Young's modulus. This study demonstrates that manipulating the concentrations of biopolymers and crosslinking agents can modulate the micro and nanomechanical properties of biopolymeric filaments.

Fabrication of self-assembled micelles based on amphiphilic oxidized sodium alginate grafted oleoamine derivatives via Schiff base reduction amination reaction for delivery of hydrophobic food active ingredients

The application of hydrophobic β-carotene in the food industry are limited due to its susceptibility to light, high temperature, pH value, and other factors, leading to poor stability and low bioavailability. To address this problem, we adopt a more green and environmentally friendly reducing agent, 2-methylpyridine borane complex (pic-BH3), instead of traditional sodium borohydride, to achieve the simple green and efficient synthesis of amphiphilic oxidized sodium alginate grafted oleoamine derivatives (OSAOLA) through the reduction amination reaction of Schiff base. The resultant OSAOLA with the degree of substitution (DS) of 7.2 %, 23.6 %, and 38.8 % were synthesized, and their CMC values ranged from 0.0095 to 0.062 mg/mL, indicating excellent self-assembly capability in aqueous solution. Meanwhile, OSAOLA showed no obvious cytotoxicity to RAW 264.7 cells, thus revealing good biocompatibility. Furthermore, β-carotene, as the hydrophobic active ingredients in foods was successfully encapsulated in the OSAOLA micelles by ultrasonic-dialysis method. The prepared drug-loaded OSAOLA micelles could maintain good stability when stored at room temperature for 7 d. Additionally, they were able to continuously release β-carotene and exert long-term effects in pH 7.4 PBS at 37 °C, effectively improving the bioavailability of β-carotene, which exhibited tremendous application potential in functional food and biomedical fields.

Fabrication of Sodium Trimetaphosphate-Based PEDOT:PSS Conductive Hydrogels

Conductive hydrogels are highly attractive for biomedical applications due to their ability to mimic the electrophysiological environment of biological tissues. Although conducting polymer polythiophene-poly-(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonate (PSS) alone exhibit high conductivity, the addition of other chemical compositions could further improve the electrical and mechanical properties of PEDOT:PSS, providing a more promising interface with biological tissues. Here we study the effects of incorporating crosslinking additives, such as glycerol and sodium trimetaphosphate (STMP), in developing interpenetrating PEDOT:PSS-based conductive hydrogels. The addition of glycerol at a low concentration maintained the PEDOT:PSS conductivity with enhanced wettability but decreased the mechanical stiffness. Increasing the concentration of STMP allowed sufficient physical crosslinking with PEDOT:PSS, resulting in improved hydrogel conductivity, wettability, and rheological properties without glycerol. The STMP-based PEDOT:PSS conductive hydrogels also exhibited shear-thinning behaviors, which are potentially favorable for extrusion-based 3D bioprinting applications. We demonstrate an interpenetrating conducting polymer hydrogel with tunable electrical and mechanical properties for cellular interactions and future tissue engineering applications.

A ternary composite hydrogel based on sodium alginate, carboxymethyl cellulose and copper-doped 58S bioactive glass promotes cutaneous wound healing in vitro and in vivo

Hydrogels offer a novel approach to wound repair. In this study, we synthesized a ternary composite using sodium alginate (SA), carboxymethyl cellulose (CMC) and copper-doped 58S bioactive glass (BG). According to our mechanical testing results, the composite made of 7 wt% CMC and 7 wt% BG (SA-7CMC-7BG) showed optimal properties. In addition, our in vitro studies revealed the biocompatibility and bioactivity of SA-7CMC-7BG, with a negative zeta potential of -31.7 mV. Scanning electron microscope (SEM) images showed 273-μm-diameter pores, cell adhesion, and anchoring. The SA-7CMC-7BG closed 90.4 % of the mechanical scratch after 2 days. An in vivo wound model using Wistar rats showed that SA-7CMC-7BG promoted wound healing, with 85.57 % of the wounds healed after 14 days. Treatment with the SA-7CMC-7BG hydrogel caused a 1.6-, 65-, and 1.87-fold increase in transforming growth factor beta (TGF-β), Col I, and vascular endothelial growth factor (VEGF) expression, respectively that prevents fibrosis and promotes angiogenesis. Furthermore, interleukin 1β (IL-1β) expression was downregulated by 1.61-fold, indicating an anti-inflammatory effect of SA-7CMC-7BG. We also observed an increase in epidermal thickness, the number of fibroblast cells, and collagen deposition, which represent complementary pathology results confirming the effectiveness of the SA-7CMC-7BG hydrogel in cutaneous wound healing.

Recent Advancements of Bioinks for 3D Bioprinting of Human Tissues and Organs

3D bioprinting is recognized as a promising biomanufacturing technology that enables the reproducible and high-throughput production of tissues and organs through the deposition of different bioinks. Especially, bioinks based on loaded cells allow for immediate cellularity upon printing, providing opportunities for enhanced cell differentiation for organ manufacturing and regeneration. Thus, extensive applications have been found in the field of tissue engineering. The performance of the bioinks determines the functionality of the entire printed construct throughout the bioprinting process. It is generally expected that bioinks should support the encapsulated cells to achieve their respective cellular functions and withstand normal physiological pressure exerted on the printed constructs. The bioinks should also exhibit a suitable printability for precise deposition of the constructs. These characteristics are essential for the functional development of tissues and organs in bioprinting and are often achieved through the combination of different biomaterials. In this review, we have discussed the cutting-edge outstanding performance of different bioinks for printing various human tissues and organs in recent years. We have also examined the current status of 3D bioprinting and discussed its future prospects in relieving or curing human health problems.

Degradable Polymeric Bio(nano)materials and Their Biomedical Applications: A Comprehensive Overview and Recent Updates

Degradable polymers (both biomacromolecules and several synthetic polymers) for biomedical applications have been promising very much in the recent past due to their low cost, biocompatibility, flexibility, and minimal side effects. Here, we present an overview with updated information on natural and synthetic degradable polymers where a brief account on different polysaccharides, proteins, and synthetic polymers viz. polyesters/polyamino acids/polyanhydrides/polyphosphazenes/polyurethanes relevant to biomedical applications has been provided. The various approaches for the transformation of these polymers by physical/chemical means viz. cross-linking, as polyblends, nanocomposites/hybrid composites, interpenetrating complexes, interpolymer/polyion complexes, functionalization, polymer conjugates, and block and graft copolymers, are described. The degradation mechanism, drug loading profiles, and toxicological aspects of polymeric nanoparticles formed are also defined. Biomedical applications of these degradable polymer-based biomaterials in and as wound dressing/healing, biosensors, drug delivery systems, tissue engineering, and regenerative medicine, etc., are highlighted. In addition, the use of such nano systems to solve current drug delivery problems is briefly reviewed.

Effect of injectable calcium alginate-amelogenin hydrogel on macrophage polarization and promotion of jawbone osteogenesis

Due to persistent inflammation and limited osteogenesis, jawbone defects present a considerable challenge in regenerative medicine. Amelogenin, a major protein constituent of the developing enamel matrix, demonstrates promising capabilities in inducing regeneration of periodontal supporting tissues and exerting immunomodulatory effects. These properties render it a potential therapeutic agent for enhancing jawbone osteogenesis. Nevertheless, its clinical application is hindered by the limitations of monotherapy and its rapid release characteristics, which compromise its efficacy and delivery efficiency. In this context, calcium alginate hydrogel, recognized for its superior physicochemical properties and biocompatibility, emerges as a candidate for developing a synergistic bioengineered drug delivery system. This study describes the synthesis of an injectable calcium amelogenin/calcium alginate hydrogel using calcium alginate loaded with amelogenin. We comprehensively investigated its physical properties, its role in modulating the immunological environment conducive to bone healing, and its osteogenic efficacy in areas of jawbone defects. Our experimental findings indicate that this synthesized composite hydrogel possesses desirable mechanical properties such as injectability, biocompatibility, and biodegradability. Furthermore, it facilitates jawbone formation by regulating the bone-healing microenvironment and directly inducing osteogenesis. This research provides novel insights into the development of bone-tissue regeneration materials, potentially advancing their clinical application.

In situ forming alginate/gelatin hydrogel scaffold through Schiff base reaction embedded with curcumin-loaded chitosan microspheres for bone tissue regeneration

In this study, we developed a biocompatible composite hydrogel that incorporates microspheres. This was achieved using a Schiff base reaction, which combines the amino and aldehyde groups present in gelatin (Gel) and oxidized alginate (OAlg). We suggest this hydrogel as a promising scaffold for bone tissue regeneration. To further boost its osteogenic capabilities and mechanical resilience, we synthesized curcumin (Cur)-loaded chitosan microspheres (CMs) and integrated them into the Gel-OAlg matrix. This formed a robust composite gel framework. We conducted comprehensive evaluations of various properties, including gelation time, morphology, compressive strength, rheological behavior, texture, swelling rate, in vitro degradation, and release patterns. A remarkable observation was that the inclusion of 30 mg/mL Cur-CMs significantly enhanced the hydrogel's mechanical and bioactive features. Over three weeks, the Gel-OAlg/Cur-CMs (30) composite showed a cumulative curcumin release of 35.57%. This was notably lower than that observed in standalone CMs and Gel-OAlg hydrogels. Additionally, the Gel-OAlg/Cur-CMs (30) hydrogel presented a reduced swelling rate and weight loss relative to hydrogels devoid of Cur-CMs. On the cellular front, the Gel-OAlg/Cur-CMs (30) hydrogel showcased superior biocompatibility. It also displayed increased calcium deposition, alkaline phosphatase (ALP) activity, and elevated osteogenic gene expression in human bone marrow mesenchymal stem cells (hBMSCs). These results solidify its potential as a scaffold for bone tissue regeneration.

Development of hydrogel-based composite scaffolds containing eggshell particles for bone regeneration applications

This study describes the development and characterization of novel composite scaffolds, made of an alginate-chitosan hydrogel matrix containing eggshell (ES) particles, for bone tissue engineering applications. Scaffolds with ES particles, either untreated or treated with phosphoric acid to create a nanotextured particle surface, were compared to scaffolds without particles. Results indicate that the nanotexturing process exposed occluded ES proteins orthologous to those in human bone extracellular matrix. Scaffolds with ES or nanotextured ES (NTES) particles had a higher porosity (81 ± 4% and 89 ± 5%, respectively) than scaffolds without particles (59 ± 5%) (p = .002 and p < .001, respectively). Scaffolds with NTES particles had a larger median pore size (113 μm [interquartile range [IQ]: 88-140 μm]) than scaffolds with ES particles (94 μm [IQ: 75-112 μm]) and scaffolds without particles (99 μm [IQ: 74-135 μm]) (p < .001 and p = .011, respectively). The compressive modulus of the scaffolds with ES or NTES particles remained low (3.69 ± 0.70 and 3.14 ± 0.62 kPa, respectively), but these scaffolds were more resistant to deformation following maximum compression than those without particles. Finally, scaffolds with ES or NTES particles allowed better retention of human mesenchymal stem cells during seeding (53 ± 12% and 57 ± 8%, respectively, vs. 17 ± 5% for scaffolds without particles; p < .001 in both cases), as well as higher cell viability up to 21 days of culture (67 ± 17% and 61 ± 11%, respectively, vs. 15 ± 7% for scaffolds without particles; p < .001 in both cases). In addition, alkaline phosphatase (ALP) activity increased up to 558 ± 164% on day 21 in the scaffolds with ES particles, and up to 567 ± 217% on day 14 in the scaffolds with NTES particles (p = .006 and p = .002, respectively, relative to day 0). Overall, this study shows that the physicochemical properties of the alginate-chitosan hydrogel scaffolds with ES or NTES particles are similar to those of cancellous bone. In addition, scaffolds with particles supported early osteogenic differentiation and therefore represent a promising new bone substitute, especially for non-load bearing applications.

A novel multifunctional chitosan-gelatin/carboxymethyl cellulose-alginate bilayer hydrogel containing human placenta extract for accelerating full-thickness wound healing

The replication of skin's dermal and epidermal morphology within a full-thickness wound using a bi-layer hydrogel to cater to their distinct needs is a compelling pursuit. Moreover, human placenta extract (HPE), containing a diverse array of bioactive agents, has proven to be effective in promoting the wound healing process and enhancing epidermal keratinocytes. This study presents a multifunctional bi-layer hydrogel incorporating HPE for accelerating full-thickness wound healing through sustained HPE release, inhibition of bacteria invasion, and promotion of cell proliferation. The upper layer of the scaffold, known as the dressing layer, is composed of carboxymethyl cellulose and sodium alginate, serving as a supportive layer for cell proliferation. The under layer, referred to as the regenerative layer, is composed of chitosan and gelatin, providing an extracellular matrix-like, porous, moist, and antibacterial environment for cell growth. The scaffold was optimized to replicate the morphology of the dermal and epidermal layers, with suitable fibroblast infiltration and a pore size of approximately 283μm. Furthermore, the degradation rate of the samples matched the wound healing rate and persisted throughout this period. The sustained HPE release rate, facilitated by the degradation rate, was optimized to reach ~98% after 28 days, covering the entire healing period. The samples demonstrated robust antibacterial capabilities, with bacterial inhibition zone diameters of and 2.63±0.12cm for S. aureus and E. coli, respectively. The biocompatibility of the samples remained at approximately 68.33±4.5% after 21 days of fibroblast cell culture. The in vivo experiment indicated that the HPE@Bilayer hydrogel promotes the formation of new blood vessels and fibroblasts during the early stages of healing, leading to the appropriate formation of granulation tissue and a wound contraction rate of (79.31±3.1)%. Additionally, it resulted in the formation of a thick epidermal layer (keratinization) that effectively covered all the impaired areas, achieving a wound contraction rate of 95.83±6.3% at the late stage of wound healing. Furthermore, immunohistochemistry staining for CD31 and TGF-β revealed that the HPE@Bilayer group had 22 blood vessels/field and 34%-66% immunoactive cells, respectively, after 14 days of healing. However, by day 21, angiogenesis and TGF-β expression had declined, demonstrating that the wounds had been successfully treated with minimal scarring.

Sodium alginate hydrogel integrated with type III collagen and mesenchymal stem cell to promote endometrium regeneration and fertility restoration

A thinner endometrium has been linked to implantation failure, and various therapeutic strategies have been attempted to improve endometrial regeneration, including the use of mesenchymal stem cells (MSCs). However, low survival and retention rates of transplanted stem cells are main obstacles to efficient stem cell therapy in thin endometrium. Collagen type III is a key component of the extracellular matrix, plays a crucial role in promoting cell proliferation and differentiation, and has been identified as the major collagen expressed at the implantation site. Herein, composite alginate hydrogel containing recombinant type III collagen (rCo III) and umbilical cord mesenchymal stem cells are developed. rCo III serves as favorable bioactive molecule, displaying that rCo III administration promotes MSCs proliferation, stemness maintenance and migration. Moreover, rCo III administration enhances cell viability and migration of mouse endometrial stromal cells (ESCs). In a mouse model of thin endometrium, the Alg-rCo III hydrogel loaded with MSCs (MSC/Alg-rCo III) significantly induces endometrial regeneration and fertility enhancement in vivo. Further studies demonstrate that the MSC/Alg-rCo III hydrogel promoted endometrial function recovery partly by regulating mesenchymal-epithelial transition of ESCs. Taken together, the combination of Alg-rCo III hydrogel and MSCs has shown promising results in promoting endometrium regeneration and fertility restoration, and may provide new therapeutic options for endometrial disease.

Photo-crosslinking modified sodium alginate hydrogel for targeting delivery potential by NO response

In recent years, the incidence of inflammatory bowel disease has gradually increased. Traditional drugs can reduce inflammation, but cannot be targeting released and often require the coordination with delivery systems. However, a good targeting performance delivery system is still scarce currently. Inflammation can trigger oxidative stress, producing large amounts of oxides such as nitric oxide (NO). Based on this, the present experiment innovatively designed a hydrogel delivery system with NO response that could be inflammation targeting. The hydrogel is composed of sodium alginate modified with glycerol methacrylate, crosslinked with NO response agent by photo-crosslinking method, which have low swelling (37 %) and good mechanical properties with a stable structure even at 55 °C. The results of in vitro digestion also indicated that the hydrogel had a certain tolerance to gastrointestinal digestion. And in the NO environment, it was interestingly found that the structure and mechanical properties of the hydrogels changed significantly. Moreover, hydrogels have good biocompatibility, which ensures their safe use in vivo. In conclusion, this NO-responsive-based delivery system is feasible and provides a new approach for drugs and active factors targeting delivery in the future.

Alginate/hyaluronic acid-based systems as a new generation of wound dressings: A review

Skin is the largest organ of the human body, which acts as a protective barrier against pathogens. Therefore, a lot of research has been carried out on wound care and healing. Creating an ideal environment for wound healing and optimizing the local and systemic conditions of the patient play critical roles in successful wound care. Many products have been developed for improving the wound environment and providing a protected and moist area for fast healing. However, there is still high demand for new systems with high efficiency. The first generation of wound dressings merely covered the wound, while the subsequent/last generations covered it and aided in healing it in different ways. In modern wound dressings, the kind of used materials and their complexity play a crucial role in the healing process. These new systems support wound healing by lowering inflammation, exudate, slough, and bacteria. This study addresses a review of alginate/hyaluronic acid-based wound dressings developed so far as well as binary and ternary systems and their role in wound healing. Our review corroborates that these systems can open up a new horizon for wounds that do not respond to usual treatments and have a long curing period.

Hydrogel Microparticles for Bone Regeneration

Hydrogel microparticles (HMPs) stand out as promising entities in the realm of bone tissue regeneration, primarily due to their versatile capabilities in delivering cells and bioactive molecules/drugs. Their significance is underscored by distinct attributes such as injectability, biodegradability, high porosity, and mechanical tunability. These characteristics play a pivotal role in fostering vasculature formation, facilitating mineral deposition, and contributing to the overall regeneration of bone tissue. Fabricated through diverse techniques (batch emulsion, microfluidics, lithography, and electrohydrodynamic spraying), HMPs exhibit multifunctionality, serving as vehicles for drug and cell delivery, providing structural scaffolding, and functioning as bioinks for advanced 3D-printing applications. Distinguishing themselves from other scaffolds like bulk hydrogels, cryogels, foams, meshes, and fibers, HMPs provide a higher surface-area-to-volume ratio, promoting improved interactions with the surrounding tissues and facilitating the efficient delivery of cells and bioactive molecules. Notably, their minimally invasive injectability and modular properties, offering various designs and configurations, contribute to their attractiveness for biomedical applications. This comprehensive review aims to delve into the progressive advancements in HMPs, specifically for bone regeneration. The exploration encompasses synthesis and functionalization techniques, providing an understanding of their diverse applications, as documented in the existing literature. The overarching goal is to shed light on the advantages and potential of HMPs within the field of engineering bone tissue.

Human Induced Pluripotent Spheroids' Growth Is Driven by Viscoelastic Properties and Macrostructure of 3D Hydrogel Environment

Stem cells, particularly human iPSCs, constitute a powerful tool for tissue engineering, notably through spheroid and organoid models. While the sensitivity of stem cells to the viscoelastic properties of their direct microenvironment is well-described, stem cell differentiation still relies on biochemical factors. Our aim is to investigate the role of the viscoelastic properties of hiPSC spheroids' direct environment on their fate. To ensure that cell growth is driven only by mechanical interaction, bioprintable alginate-gelatin hydrogels with significantly different viscoelastic properties were utilized in differentiation factor-free culture medium. Alginate-gelatin hydrogels of varying concentrations were developed to provide 3D environments of significantly different mechanical properties, ranging from 1 to 100 kPa, while allowing printability. hiPSC spheroids from two different cell lines were prepared by aggregation (⌀ = 100 µm, n > 1 × 104), included and cultured in the different hydrogels for 14 days. While spheroids within dense hydrogels exhibited limited growth, irrespective of formulation, porous hydrogels prepared with a liquid-liquid emulsion method displayed significant variations of spheroid morphology and growth as a function of hydrogel mechanical properties. Transversal culture (adjacent spheroids-laden alginate-gelatin hydrogels) clearly confirmed the separate effect of each hydrogel environment on hiPSC spheroid behavior. This study is the first to demonstrate that a mechanically modulated microenvironment induces diverse hiPSC spheroid behavior without the influence of other factors. It allows one to envision the combination of multiple formulations to create a complex object, where the fate of hiPSCs will be independently controlled by their direct microenvironment.

Human Chondrocytes, Metabolism of Articular Cartilage, and Strategies for Application to Tissue Engineering

Hyaline cartilage, which is characterized by the absence of vascularization and innervation, has minimal self-repair potential in case of damage and defect formation in the chondral layer. Chondrocytes are specialized cells that ensure the synthesis of extracellular matrix components, namely type II collagen and aggregen. On their surface, they express integrins CD44, α1β1, α3β1, α5β1, α10β1, αVβ1, αVβ3, and αVβ5, which are also collagen-binding components of the extracellular matrix. This article aims to contribute to solving the problem of the possible repair of chondral defects through unique methods of tissue engineering, as well as the process of pathological events in articular cartilage. In vitro cell culture models used for hyaline cartilage repair could bring about advanced possibilities. Currently, there are several variants of the combination of natural and synthetic polymers and chondrocytes. In a three-dimensional environment, chondrocytes retain their production capacity. In the case of mesenchymal stromal cells, their favorable ability is to differentiate into a chondrogenic lineage in a three-dimensional culture.

Using chitosan, hyaluronic acid, alginate, and gelatin-based smart biological hydrogels for drug delivery in oral mucosal lesions: A review

AIMS

Oral mucosal diseases can lead to pain, difficulty speaking and eating, psychological distress, and cancer. Topical drug delivery using biological macromolecules, specifically hydrogels, is gaining interest due to the drawbacks of conventional treatments for oral mucosal lesions.

SCOPE

Biological hydrogels made from natural polymers and their derivatives, such as chitosan, hyaluronic acid, alginate, and gelatin, represent promising alternatives to conventional oral medication delivery methods. Topical drug delivery is beneficial for oral mucosal lesions as it can directly target the affected area, especially with the development of smart stimuli-responsive hydrogels, which allow for more controlled drug release. Biological hydrogels have already been used to deliver drugs like lidocaine and nystatin. This review summarizes the current research on applying smart natural polymer-based hydrogels for drug delivery in oral mucosal lesions.

CONCLUSION

Smart biological hydrogels show great promise as topical drug delivery systems for oral mucosal lesions, offering sustained drug release, increased therapeutic efficacy, and minimized systemic complications. Technological advancement is expected to lead to the development of more effective and safer drug delivery systems. The potential benefits of biological polymer-based hydrogels make them an exciting area of research for oral mucosal lesion treatment.