Recent advances in 3D printed cellulose-based wound dressings: A review on in vitro and in vivo achievements

Cellulose-based hydrogels enhanced with bioactive molecules for optimal chronic diabetic wound management

Hydrogels are three-dimensional structures that replicate natural tissues' extracellular matrix (ECM). They are essential for transporting exudates, gases, and moisture and facilitating cellular interactions in tissue engineering and wound healing. The choice of primary material in designing the scaffold is necessary to be paid more attention rather than common sources, including plant fibres like cotton, bamboo, and algae, as well as bacterial and marine-derived materials. Among them, cellulose-based polymers are especially valued for their biocompatibility and ability to promote wound healing. Chronic diabetic wounds pose unique treatment challenges, such as necrosis and infection risks. Consequently, a growing interest is in incorporating bioactive molecules into cellulose-based hydrogels. This article investigates how these infused hydrogels enhance the healing process in chronic diabetic wounds, examining various loading and crosslinking techniques alongside their clinical applications. It also discusses the benefits and limitations of bioactive molecules and their interactions with hydrogels to improve treatment strategies.

Advancements in Cellulose-Based Materials for CO2 Capture and Conversion

This study explores the recent advances of cellulose-based materials in the context of carbon capture and conversion amid the global imperative to reduce CO2emissions. The review emphasizes the critical importance of selecting suitable materials for establishing a robust and secure carbon capture technology. From elucidating celluloses' molecular structure and unique properties to detailing the advancements in CO2 capture technologies, the narrative provides a comprehensive understanding of the intricate interplay between cellulose and sustainable CO2 management. The exploration extends to the design and synthesis of cellulose-based adsorbents, challenges in implementation, showcasing emerging trends and potential breakthroughs. Emphasizing the significance of cellulose in the circular carbon economy, this review serves as a beacon for interdisciplinary collaboration, urging further research and implementation for a greener and more sustainable future. A comprehensive overview of recent developments on cellulose-based aerogels, films, composites, and solid adsorbents in the field of carbon capture. It further elucidates the research mechanisms involved in utilizing cellulose-based materials to convert CO2 into formic acid, methanol, carbonate, and CO, offering detailed insights. The review concludes by addressing the challenges and key issues associated with cellulose-based materials in the context of carbon capture and utilization.

Synergistic enhancement of hydrophobicity and mechanical properties of cellulose paper by (3-glycidoxypropyl) trimethoxy and rosin

Cellulose-based paper is inherently poor in hydrophobicity and mechanical strength, limiting its practical applications in daily life such as packaging materials, water-resistant labels, and disposable tableware. This study aimed to develop an effective and eco-friendly strategy to address these limitations by enhancing the hydrophobicity and mechanical properties of cellulose paper. To achieve this, an internal sizing agent was prepared by combining (3-glycidoxypropyl) trimethoxy (GPS) with natural rosin. This sizing agent was applied to cellulose paper, and its effectiveness was evaluated. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed the successful introduction of rosin and GPS into the cellulose fiber network, forming covalent bonds. The variation in the microstructure and surface elemental distribution of the sizing cellulose paper was further analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Thermogravimetric analysis (TGA) was conducted to evaluate the improved thermostability of the sizing cellulose paper. These structural improvements, including covalent bond formation and gap filling, contributed to the enhanced hydrophobicity and mechanical properties of the paper. This study provides a convenient and cost-effective approach to enhancing the functional properties of cellulose paper, offering new possibilities for its practical applications in eco-friendly packaging materials, disposable paper products, and high-performance paper-based packaging.

Combining antibacterial and wound healing features: Xanthan gum/guar gum 3D-printed scaffold tuned with hydroxypropyl-β-cyclodextrin/thymol and Zn2

Biofilm formation on biological and material surfaces represents a heavy health and economic burden for both patient and society. To contrast this phenomenon, medical devices combining antibacterial and pro-wound healing abilities are a promising strategy. In the present work, Xanthan gum/Guar gum (XG/GG)-based scaffolds were tuned with thymol and Zn2+ to obtain wound dressings that combine antibacterial and antibiofilm properties and favour the healing process. The tuning process preserved the 3D extrusion-based printability of the XG/GG ink. Scaffolds swelling profile was assessed in PBS pH 7.4, and the resistance to compressive forces was studied using a texturometer. The scaffolds microarchitectures were analyzed by SEM, while ATR-FTIR spotlighted the chemical modifications of the customized materials. Thymol and Zn2+ release was analyzed in biologically relevant media, showing a burst release in the first hours. The antibacterial properties were confirmed against S. aureus, P. aeruginosa, and S. epidermidis by isothermal microcalorimetry and biofilm viable cell counting. Incorporation of hydroxypropyl-β-cyclodextrin (HPβCD) improved thymol loading (7- and 14-times higher thymol content) and enhanced the antimicrobial and antioxidant performances of the dressing, while the presence of Zn2+ strongly potentiated the antimicrobial activity, showing a potent antibiofilm response in both Gram-positive and Gram-negative strains of clinical concern. The thymol and Zn2+ combination led to a reduction of 99.95 %, 99.99 %, and 98.26 %, of biofilm formation against S. aureus, P. aeruginosa, and S. epidermidis, respectively. Furthermore, the scaffolds demonstrated good hemocompatibility, cytocompatibility, tissue integration and pro-angiogenic features in an in ovo CAM model.

Hemostatic and antimicrobial properties of chitosan-based wound healing dressings: A review

Uncontrolled bleeding and microbial infections pose significant hurdles in wound healing, and the use of specialized functional dressings is pivotal in overcoming these obstacles. Among the various wound dressings currently under investigation, those based on chitosan and its derivatives have garnered significant attention due to their superior biocompatibility, antimicrobial properties, hemostatic capabilities, and healing promoting ability. In this comprehensive review, we initially delve into the hemostatic capabilities of chitosan, elucidating its interactions with blood cells and plasma proteins. We also dissect the intricate antimicrobial mechanisms of chitosan, which operate through both intracellular and extracellular pathways. The centerpiece of this review is the systematic classification of dressings based on chitosan and its derivatives, across various forms, such as hydrogels, sponges, membranes, fibers, and powders. This is followed by an exhaustive analysis of their hemostatic and antibacterial efficacy in wound healing, providing a robust foundation for further research and the advancement of clinical applications in the field.

All-cellulose resin for 3D printing hydrogels via digital light processing (DLP)

3D printing has emerged as a transformative technology in sustainable manufacturing, enabling rapid prototyping, minimizing material waste, and reducing the carbon footprint associated with traditional methods. However, their reliance on fossil-based materials limits their broad application. This study presents a novel approach for developing a single-component, fully cellulosic, natural-based resin for 3D printing hydrogels using digital light processing (DLP). Cellulose was dissolved in an aqueous alkali/urea system and modified to obtain photopolymerizable derivatives. Two cellulose sources were used: Avicel® and cellulose pulp obtained from an industrial process. The single-polymer resins produced dimensionally stable, free-standing 3D objects with good resolution and shape fidelity. Despite the low polymer concentration (2.5 and 5 wt%), the cellulose resins exhibited fast curing kinetics, producing hydrogels with good mechanical properties, capable of withstanding compressive stress up to 135 kPa. Additionally, the printed hydrogels absorbed and retained large amounts of water (up to 427 %), while maintaining their shape and integrity in acidic and alkaline media. The hydrogels were stable to hydrolytic degradation, maintained their shape for up to four weeks, and were cytocompatible with fibroblast cells, indicating their potential for biomedical applications.

3D printed skin dressings manufactured with spongin-like collagen from marine sponges: physicochemical properties andin vitrobiological analysis

The search for innovative materials for manufacturing skin dressings is constant and high demand. In this context, the present study investigated the effects of a 3D printed skin dressing made of spongin-like collagen (SC) extract from marine sponge (Chondrilla caribensis), used in 3 concentrations of SC and alginate (C1, C2, C3). For this proposal, the physicochemical, morphological andin vitrobiological results were investigated. The results demonstrated that, after immersion, C2 presented a higher mass loss and C3 present a higher pH in experimental periods. Also, a higher porosity was observed for C1 and C2 skin dressings, with a higher swelling ratio for C2. For Fourier transform infrared, peaks of Amide A, -CH2, -COOH and C-O-C were seen. Moreover, the macroscopic image demonstrated a skin dressing with rough surface and grayish color that is naturally observed inChondrilla caribensis. For scanning electron microscopy analysis the presence of pores could be observed for all skin dressings, with fibers disposed in layers. Thein vitroanalyses demonstrated the viability of HFF-1 and L929 cell lines 70% of the values found for cell proliferation compared to Control Group. Furthermore, the cell adhesion analysis demonstrated that both cell lines adhered to the 3 different skin dressings and non-cytotoxicity was observed. Taking together, all the results suggest that the skin dressings are biocompatible and present non-cytotoxicity in thein vitrostudies, being considered a suitable material for tissue engineering proposals.

Structure-property relations in rheology of cellulose nanofibrils-based hydrogels

Hydrogels prepared from self-assembled cellulose nanofibrils (CNFs) are widely used in biomedicine, electronics and environmental technology. Their ability to serve as inks for extrusion-based 3D printing is conventionally evaluated by means of rheological tests. A model is developed that describes the response of CNF gels in small- and large-amplitude oscillatory tests in a unified manner. The model involves a reasonably small number of material parameters, ensures good agreement between results of simulation and observations in oscillatory tests and correctly predicts the stress-strain Lissajous curves, experimental data in hysteresis loop tests, and measurements of the steady-state viscosity. The model is applied to analyze how composition and preparation conditions for CNF gels affect transition from shear thinning to weak strain overshoot in large-amplitude shear oscillatory tests. Based on the model, simple relations are derived for the fractal dimension of CNF clusters and the storage modulus of gels prepared in aqueous solutions of multivalent salts. The validity of these equations is confirmed by comparison of their predictions with observations in independent tests.

Construction of piezoelectric, conductive and injectable hydrogels to promote wound healing through electrical stimulation

Piezoelectric, conductive, and injectable hydrogel (SPG hydrogel) is constructed to rapidly close wounds, efficiently harvest biomechanical energy from animal motion, and generate electrical stimulation for electrotherapy of wound healing. 3-amino-4-methoxybenzoic acid (AMB) monomer was polymerized and grafted onto the gelatin, which was further crosslinked using EDC/NHS and embedded with strontium titanate nanoparticles (80.5 wt%), forming SPG hydrogel. This SPG hydrogel had high tissue adhesion ability, and could generate the output voltage (maximum output voltage 1 V) and current (maximum output current 0.5 nA) upon mechanical bending, promoting NIH-3T3 cell migration and proliferation. Upon application to the mice wound model, the SPG hydrogel rapidly closed the skin wound, smoothed the wound's appearance, reduced the remaining wound size, and increased epidermal thickness, demonstrating remarkable wound healing capabilities. This study suggests that the body motion-promoted electrotherapy offers a promising strategy for wound healing. STATEMENT OF SIGNIFICANCE: Piezoelectric nanomaterials are often incorporated into hydrogels to create piezoelectric hydrogels for wound healing. However, piezoelectric nanomaterials tend to agglomerate within the hydrogel matrix, and the hydrogel's low conductivity hinders efficient electron transfer. Together, both factors significantly reduce the piezoelectric effect. In this study, we developed an SPG hydrogel to improve the homogeneity and conductivity of the piezoelectric hydrogel. We first designed a conductive PG hydrogel and then immoblized piezoelectric STO nanoparticles within its matrix through coordination chemistry. Upon mechanical deformation, the uniformly distributed STO nanoparticles can generate electricity, which can efficiently transfer through the conductive matrix to the hydrogel's surface. This design shows great potential for wound healing applications.

Hydrogels and hydrogel-based drug delivery systems for promoting refractory wound healing: Applications and prospects

Refractory wounds represent a significant health concern that presents considerable challenges within clinical practice. The healing process of refractory wounds, which involves various cell types and biologically active molecules, is dynamically influenced by multiple factors, including diabetes, infections, and inflammation. Owing to their hydrophilicity, biocompatibility, and capacity for drug loading, hydrogels have emerged as promising and innovative biomaterials for enhancing wound healing. In recent decades, hydrogels with inherent therapeutic properties have been identified. Moreover, advanced hydrogel-based drug delivery systems have been developed to facilitate the sustained and controlled release of therapeutic agents at the site of refractory wounds. This review aims to summarize recent advancements and applications of hydrogels, including those with intrinsic therapeutic properties and hydrogel-based drug delivery systems, in the treatment of refractory wounds. Additionally, we discuss the limitations associated with hydrogel applications and propose future perspectives, which will lead to ongoing efforts to optimize hydrogels as ideal biomaterials for refractory wound healing.

Advances in Cellulose-Based Hydrogels: Current Trends and Challenges

This paper provides a solid foundation for understanding the synthesis, properties, and applications of cellulose-based gels. It effectively showcases the potential of these gels in diverse applications, particularly in biomedicine, and highlights key synthesis methods and properties. However, to push the field forward, future research should address the gaps in understanding the environmental impact, mechanical stability, and scalability of cellulose-based gels, while also considering how to overcome barriers to their industrial use. This will ultimately allow for the realization of cellulose-based gels in large-scale, sustainable applications.

Antibacterial carboxymethyl chitosan hydrogel loaded with antioxidant cascade enzymatic system for immunoregulating the diabetic wound microenvironment

Diabetic wound healing faces several complex challenges, such as hypoxia, oxidative stress, and bacterial infections, which severely inhibit the wound-healing process. Herein, a quaternary ammonium salt-crosslinked carboxymethyl chitosan hydrogel (TPC) with excellent antioxidant and antibacterial properties was developed to immunoregulate the diabetic wound microenvironment. The TPC hydrogel was prepared by first mixing carboxymethyl chitosan (CMCS) and protocatechualdehyde (PA), followed by the addition of a quaternary ammonium cross-linker (TSPBA) and a superoxide dismutase (SOD)-catalase (CAT) cascade system. The immobilized SOD and CAT retained their activity, continuously converting endogenous ·O2- and H2O2 to O2 and H2O. PA also provided the TPC hydrogel excellent oxygen and nitrogen radical scavenging capacity. The quaternary ammonium groups in TSPBA significantly enhanced the inherent antibacterial ability of CMCS-based hydrogels. In diabetic wound-healing experiments, this porous and adhesive TPC hydrogel effectively closed wounds and regenerated skin tissue, resulting in shorter wound edges, thicker granulation, and higher collagen deposition levels compared with other groups. The TPC hydrogel also promoted macrophage polarization toward the M2 phenotype, accelerating wound healing by upregulating IL-10 expression, downregulating IL-6 expression, and enhancing angiogenesis. These results demonstrate the great potential of TPC hydrogel as a promising therapeutic dressing for treating diabetic wounds.

Lysozyme-enhanced cellulose nanofiber, chitosan, and graphene oxide multifunctional nanocomposite for potential burn wound healing applications

The demand for advanced biomaterials in medical treatments is rapidly expanding. To address this demand, a nanocomposite of cellulose nanofiber (CNF) with chitosan (Ch) and graphene oxide (GO) was developed for burn wound treatment. The CNF-Ch-GO nanocomposites were characterized and their biological properties were evaluated. Microscopic images showed a uniform distribution of CNF, Ch, and GO with a porous structure. ATR-FTIR and XRD analyses confirmed the chemical structures, while a thermogravimetric study confirmed the stability of CNF-Ch-GO nanocomposite under a N2 atmosphere. The synthesized CNF-Ch-GO nanocomposite exhibited rapid absorption, absorbing 1781.7 ± 53.7 % PBS in 2 min. It demonstrated a Young's modulus of 11.90 ± 0.06 MPa in a hydrated condition, indicating its mechanical stability in water. Furthermore, it displayed excellent biocompatibility and hemocompatibility with 96.23 ± 12.21 % cell viability and 0.21 ± 0.08 % of hemolysis. Additionally, the blood clotting index of CNF-Ch-GO was comparable to that of standard dressing gauze. To enhance antimicrobial efficacy, CNF-Ch-GO was conjugated with lysozyme. This biotic and abiotic conjugation resulted in 92.17 % ± 3.02 % and 94.99 ± 2.1 % eradication of Escherichia coli and Staphylococcus aureus, respectively. The enhanced antimicrobial properties, biocompatibility, and mechanical stability of the superabsorbent CNF-Ch-GO nanocomposite indicate its significant potential for advanced burn wound healing applications.

3D printing and bioprinting in the battle against diabetes and its chronic complications

Diabetes is a metabolic disorder characterized by high blood sugar. Uncontrolled blood glucose affects the circulatory system in an organism by intervening blood circulation. The high blood glucose can lead to macrovascular (large blood vessels) and microvascular (small blood vessels) complications. Due to this, the vital organs (notably brain, eyes, feet, heart, kidneys, lungs and nerves) get worsen in diabetic patients if not treated at the earliest. Therefore, acquiring treatment at an appropriate time is very important for managing diabetes and other complications that are caused due to diabetes. The root cause for the occurrence of various health complications in diabetic patients is the uncontrolled blood glucose levels. This review presents a consolidated account of the applications of various types of three-dimensional (3D) printing and bioprinting technologies in treating diabetes as well as the complications caused due to impaired blood glucose levels. Herein, the development of biosensors (for the diagnosis), oral drug formulations, transdermal drug carriers, orthotic insoles and scaffolds (for the treatment) are discussed. Next to this, the fabrication of 3D bioprinted organs and cell-seeded hydrogels (pancreas engineering for producing insulin and bone engineering for managing bone defects) are explained. As the final application, 3D bioprinting of diabetic disease models for high-throughput screening of ant-diabetic drugs are discussed. Lastly, the challenges and future perspective associated with the use of 3D printing and bioprinting technologies against diabetes and its related chronic complications have been put forward.

Biofabrication of Cellulose-based Hydrogels for Advanced Wound Healing: A Special Emphasis on 3D Bioprinting

Even with the current advancements in wound management, addressing most skin injuries and wounds continues to pose a significant obstacle for the healthcare industry. As a result, researchers are now focusing on creating innovative materials utilizing cellulose and its derivatives. Cellulose, the most abundant biopolymer in nature, has unique properties that make it a promising material for wound healing, such as biocompatibility, tunable physiochemical characteristics, accessibility, and low cost. 3D bioprinting technology has enabled the production of cellulose-based wound dressings with complex structures that mimic the extracellular matrix. The inclusion of bioactive molecules such as growth factors offers the ability to aid in promoting wound healing, while cellulose creates an ideal environment for controlled release of these biomolecules and moisture retention. The use of 3D bioprinted cellulose-based wound dressings has potential benefits for managing chronic wounds, burns, and painful wounds by promoting wound healing and reducing the risk of infection. This review provides an up-to-date summary of cellulose-based dressings manufactured by 3D bioprinting techniques by looking into wound healing biology, biofabrication methods, cellulose derivatives, and the existing cellulose bioinks targeted toward wound healing.

Recrystallization of Cellulose, Chitin and Starch in Their Individual and Native Forms

Semi-crystalline natural polymers are involved in many technological processes. Biopolymers having identical chemical compositions can differ in reactivity in heterogeneous transformations depending on their crystal structure (polymorphic modification). This paper compares the crystal structure recrystallization processes occurring in natural polysaccharides (cellulose, chitin, and starch) in the individual form and as a component of native biomass. Aqueous treatment of pre-amorphized semi-crystalline biopolymers was shown to result in swelling, thus alleviating the kinetic restrictions imposed on the restoration of crystalline regions and phase transition to the thermodynamically more stable polymorphic modification. During recrystallization, cellulose I in the individual form and within plant-based biomass undergoes a transition to the more stable cellulose II. A similar situation was demonstrated for α- and β-chitin, which recrystallize only into the α-polymorphic modification in the case of both individual polymers and native materials. Recrystallization of A-, B-, and C-type starch, both in the individual form and within plant-based flour, during aqueous treatment, results in a phase transition, predominantly to the B-type starch. The recrystallization process depends on the temperature of aqueous treatment; longer treatment duration has almost no effect on the recrystallization degree of polymers, both in the individual form and within native materials.

AI energized hydrogel design, optimization and application in biomedicine

Traditional hydrogel design and optimization methods usually rely on repeated experiments, which is time-consuming and expensive, resulting in a slow-moving of advanced hydrogel development. With the rapid development of artificial intelligence (AI) technology and increasing material data, AI-energized design and optimization of hydrogels for biomedical applications has emerged as a revolutionary breakthrough in materials science. This review begins by outlining the history of AI and the potential advantages of using AI in the design and optimization of hydrogels, such as prediction and optimization of properties, multi-attribute optimization, high-throughput screening, automated material discovery, optimizing experimental design, and etc. Then, we focus on the various applications of hydrogels supported by AI technology in biomedicine, including drug delivery, bio-inks for advanced manufacturing, tissue repair, and biosensors, so as to provide a clear and comprehensive understanding of researchers in this field. Finally, we discuss the future directions and prospects, and provide a new perspective for the research and development of novel hydrogel materials for biomedical applications.

Extracellular matrix-mimetic immunomodulatory fibrous scaffold based on a peony stamens polysaccharide for accelerated wound healing

Re-establishment of the extracellular matrix (ECM) in wound tissue is critical for activating endogenous tissue repair. In this study, we designed an ECM-like scaffold material using plant polysaccharides and assessed its efficacy through in vitro and in vivo experiments. The scaffold accelerates wound healing by regulating inflammatory responses and accelerating tissue regeneration. Briefly, we isolated two polysaccharides of varying molecular weights from peony stamens. One of the polysaccharides exhibits potent immunomodulatory and tissue regeneration activities. We further prepared electrospinning materials containing this polysaccharide. In vitro investigations have demonstrated the polysaccharide's ability to modulate immune responses by targeting TLR receptors. In vivo experiments utilizing a scaffold composed of this polysaccharide showed accelerated healing of full-thickness skin wounds in mice, promoting rapid tissue regeneration. In conclusion, our study shows that this scaffold can mobilize the endogenous regenerative capacity of tissues to accelerate repair by mimicking the characteristics of ECM. The overall study has implications for the design of new, effective, and safer tissue regeneration strategies.

Stimuli-Responsive Hydrogels for Protein Delivery

Proteins and peptides are potential therapeutic agents, but their physiochemical properties make their use as drug substances challenging. Hydrogels are hydrophilic polymeric networks that can swell and retain high amounts of water or biological fluids without being dissolved. Due to their biocompatibility, their porous structure, which enables the transport of various peptides and proteins, and their protective effect against degradation, hydrogels have gained prominence as ideal carriers for these molecules' delivery. Particularly, stimuli-responsive hydrogels exhibit physicochemical transitions in response to subtle modifications in the surrounding environment, leading to the controlled release of entrapped proteins or peptides. This review is focused on the application of these hydrogels in protein and peptide delivery, including a brief overview of therapeutic proteins and types of stimuli-responsive polymers.