Biodegradable Cellulose-based Hydrogels: Design and Applications

Synthesis and Applications of Carboxymethyl Cellulose Hydrogels

Hydrogels are basic materials widely used in various fields, especially in biological engineering and medical imaging. Hydrogels consist of a hydrophilic three-dimensional polymer network that rapidly expands in water and can hold a large volume of water in its swelling state without dissolving. These characteristics have rendered hydrogels the material of choice in drug delivery applications. In particular, carboxymethyl cellulose (CMC) hydrogels have attracted considerable research attention for the development of safe drug delivery carriers because of their non-toxicity, good biodegradability, good biocompatibility and low immunogenicity. Aiming to inspire future research in this field, this review focuses on the current preparation methods and applications of CMC gels and highlights future lines of research for the further development of diverse applications.

Injectable light-assisted thermo-responsive methylcellulose-sodium humate hydrogel proposed for photothermal ablation and localized delivery of cisplatin

This study aimed to develop injectable light-assisted thermo-responsive methylcellulose hydrogels filled with sodium humate, which were proposed for photothermal ablation and localized cisplatin delivery. Sodium humate converts light energy from laser beams into thermal energy, which causes methylcellulose to gel, thereby controlling the release of chemotherapy agents. Meanwhile, light emission causes to the photothermal ablation of tumor cells. For determining the optimal production conditions, different concentrations of sodium humate and light emission times were investigated. Results show that hydrogel uniformity is highly dependent on variables. An increase in sodium humate concentration and emission time resulted in a slight reduction in swelling ratio and an increase in durability. According to the simulation conditions, the cisplatin release profile was consistent with a non-Fickian mechanism with a predominant erosion contribution. In conjugation with increasing light emission time and sodium humate content, the storage modulus and viscosity increased, demonstrating hydrogel’s sol-gel transition and long-lasting durability. The intrinsic fluorescence spectroscopy study revealed that the hydrogel-model protein complex empowered hydrogel bio-performance. Laser emission and cisplatin release synergistically reduced the number of viable osteosarcoma cell lines, suggesting the possibility of tumor ablation. This study describes the potential of simultaneous photothermal therapy and chemotherapy in osteosarcoma treatment, laying the groundwork for future preclinical and clinical trials.

Effects of trehalose and polyacrylate-based hydrogels on tomato growth under drought

Hydrophilic amendments can enhance soil moisture content, which, in turn, can improve crop health under drought conditions. Understanding how different hydrogels interact with specific crops is necessary for optimal application. The soil conditioning abilities of a trehalose hydrogel and polyacrylate-based hydrogel were evaluated for tomatoes (Solanum lycopersicum) subjected to drought. Tomato plants were transplanted into individual pots with soil that contained trehalose hydrogel (0.4 wt%), polyacrylate-based hydrogel (0.4 wt%), or no hydrogel and subjected to a well-watered treatment or to pronounced soil drought, with or without rewatering. The health of tomato plants was monitored by measuring leaf total chlorophyll (a + b) concentration, leaf water potential (Ψ_leaf), stomatal conductance (g _s) and relative growth rate (RGR). The polyacrylate-based hydrogel, but not the trehalose hydrogel, improved tomato plant function under drought conditions, as indicated by improved g _s and RGR relative to the well-watered control. However, when subjected to a second drought, neither hydrogel was effective, and neither prolonged survival. The more hydrophilic polyacrylate-based hydrogel demonstrated promise in improving the growth of tomato plants under drought when included as a soil amendment at 0.4 wt%. This research is important for understanding the effects of these hydrogels as soil conditioners in drought prone systems.

Functional Thermoresponsive Hydrogel Molecule to Material Design for Biomedical Applications

Temperature-induced, rapid changes in the viscosity and reproducible 3-D structure formation makes thermos-sensitive hydrogels an ideal delivery system to act as a cell scaffold or a drug reservoir. Moreover, the hydrogels’ minimum invasiveness, high biocompatibility, and facile elimination from the body have gathered a lot of attention from researchers. This review article attempts to present a complete picture of the exhaustive arena, including the synthesis, mechanism, and biomedical applications of thermosensitive hydrogels. A special section on intellectual property and marketed products tries to shed some light on the commercial potential of thermosensitive hydrogels.

Synthesis and Evaluation of Finasteride-Loaded HPMC-Based Nanogels for Transdermal Delivery: A Versatile Nanoscopic Platform

Herein, we report nanogels comprising diverse feed ratio of polymer hydroxypropyl methylcellulose (HPMC), monomer acrylic acid (AA), and cross-linker methylene bisacrylamide (MBA) fabricated for transdermal delivery of finasteride (FIN). Free radical solution polymerization method with subsequent condensation was employed for the synthesis using ammonium per sulfate (APS) and sodium hydrogen sulfite (SHS) as initiators. Carbopol-940 gel (CG) was formulated as assisting platform to deliver FIN nanogels transdermally. Developed formulations were evaluated by several in vitro, ex vivo, and in vivo parameters such as particle size and charge distribution analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffractogram (XRD), rheological testing, in vitro swelling and drug release, and ex vivo skin permeation, irritation, and toxicity assessment. The results endorsed the nanogel formation (117.3 ± 29.113 nm), and the impact of synthesizing method was signified by high yield of nanogels (≈91%). Efficient response for in vitro swelling and FIN release was revealed at pH 5.5 and 7.4. Skin irritation and toxicity assessment ensured the biocompatibility of prepared nanocomposites. On the basis of the results obtained, it can be concluded that the developed nanogels were stable with excellent drug permeation profile across skin.

Towards the Preparation of a Hydrogel from Lyophilisates of the Aloe arborescens Aqueous Extract

Aloe gel is a medicinal raw material with proven pharmacological activity. The health-promoting properties of other species of Aloe upon topical application prompted us to develop a formulation for the topical application of A. arborescence species. As a result of the gel preparation from the aqueous lyophilized extracts of three-year-old leaves of A. arborescence, no changes in the composition of the content of aloins A and aloenin A were found. The potential to neutralize free radicals was tested using DPPH and CUPRAC techniques, which confirmed the anti-radical activity of the lyophilisate. Screening of the inhibition of enzymes, the hyperactivity of which is associated with adverse changes in the skin of a pro-inflammatory nature, was performed. Importantly, using the PAMPA SKIN model, the possibility of the penetration of selected extract compounds (aloin A and aloenin A) through the skin was proven. Then, two formulations were prepared based on sodium alginate and hydroxypropyl methylcellulose (HPMC) and the hydrogels were characterized (rheological analysis, drug release profiles, permeability, and stability studies). HPMC-based hydrogel was the one with a targeted release of active substances and greater stability. Aloe arborescens hydrogel matrices seem to be a promising treatment strategy for inflammatory surface damage based on “green technology” at the stage of extract preparation and development of the drug form for topical application.

Hydrogel Application in Urban Farming: Potentials and Limitations—A Review

Urban agriculture plays a vital role in ensuring the self-sufficiency of a great variety of fresh vegetables and nutrients. It promotes a sustainable food system as well as reducing the dependency on imports for the growing population. Urban farming has made it possible for agriculture practices to be implemented anywhere at any time in a sophisticated way. Hydrogel has been introduced in urban agriculture in the past few decades. However, the application of hydrogel in urban agriculture is still being explored in terms of hydrogel types, structure, physical and chemical properties, change due to external factors, and its suitability for different plant species. This review discusses the potentials and limitations of hydrogel in different application conditions. We present the state of knowledge on hydrogel production and crosslinking methods, hydrogel characteristics, water absorption and release mechanisms of hydrogel, hydrogel advantages and limitations, and current and future applications in urban farming.

Proof of Concept of Biopolymer Based Hydrogels as Biomimetic Oviposition Substrate to Develop Tiger Mosquitoes (Aedes albopictus) Cost-Effective Lure and Kill Ovitraps

Pest management is looking for green and cost-effective innovative solutions to control tiger mosquitoes and other pests. By using biomimetic principles and biocompatible/biodegradable biopolymers, it could be possible to develop a new approach based on substrates that selectively attract insects by reproducing specific natural environmental conditions and then kill them by hosting and delivering a natural biopesticide or through mechanical action (biomimetic lure and kill approach, BL&K). Such an approach can be theoretically specialized against tiger mosquitoes (BL&K-TM) by designing hydrogels to imitate the natural oviposition site’s conditions to employ them inside a lure and kill ovitraps as a biomimetic oviposition substrate. In this work, the hydrogels have been prepared to prove the concept. The study compares lab/on-field oviposition between standard substrates (absorbing paper/masonite) and a physical and chemically crosslinked hydrogel composition panel. Then the best performing is characterized to evaluate a correlation between the hydrogel’s properties and oviposition. Tests identify a 2-Hydroxyethylcellulose (HEC)-based physical hydrogel preparation as five times more attractive than the control in a lab oviposition assay. When employed on the field in a low-cost cardboard trap, the same substrate is seven times more capturing than a standard masonite ovitrap, with a duration four times longer.

Use of Carbotrace 480 as a Probe for Cellulose and Hydrogel Formation from Defibrillated Microalgae

Carbotrace 480 is a commercially available fluorescent optotracer that specifically binds to cellulose’s glycosidic linkages. Herein, the use of Carbotrace 480 is reported as an analytical tool for linking cellulose content to hydrogel formation capability in defibrillated celluloses obtained from proprietary microalgae. Defibrillated celluloses obtained from acid-free hydrothermal microwave processing at low temperature (160 °C) showed poor hydrogel formation attributed to a low cellulose concentration as evidenced through the lack of Carbotrace fluorescence. High temperature (220 °C) processing afforded reasonable gels commensurate with a higher cellulose loading and stronger response to Carbotrace.

Viability and Functionality of Neonatal Porcine Islet-like Cell Clusters Bioprinted in Alginate-Based Bioinks

The transplantation of pancreatic islets can prevent severe long-term complications in diabetes mellitus type 1 patients. With respect to a shortage of donor organs, the transplantation of xenogeneic islets is highly attractive. To avoid rejection, islets can be encapsulated in immuno-protective hydrogel-macrocapsules, whereby 3D bioprinted structures with macropores allow for a high surface-to-volume ratio and reduced diffusion distances. In the present study, we applied 3D bioprinting to encapsulate the potentially clinically applicable neonatal porcine islet-like cell clusters (NICC) in alginate-methylcellulose. The material was additionally supplemented with bovine serum albumin or the human blood plasma derivatives platelet lysate and fresh frozen plasma. NICC were analysed for viability, proliferation, the presence of hormones, and the release of insulin in reaction to glucose stimulation. Bioprinted NICC are homogeneously distributed, remain morphologically intact, and show a comparable viability and proliferation to control NICC. The number of insulin-positive cells is comparable between the groups and over time. The amount of insulin release increases over time and is released in response to glucose stimulation over 4 weeks. In summary, we show the successful bioprinting of NICC and could demonstrate functionality over the long-term in vitro. Supplementation resulted in a trend for higher viability, but no additional benefit on functionality was observed.

Intravitreal Injectable Hydrogels for Sustained Drug Delivery in Glaucoma Treatment and Therapy

Glaucoma is extensively treated with topical eye drops containing drugs. However, the retention time of the loaded drugs and the in vivo bioavailability of the drugs are highly influenced before reaching the targeted area sufficiently, due to physiological and anatomical barriers of the eye, such as rapid nasolacrimal drainage. Poor intraocular penetration and frequent administration may also cause ocular cytotoxicity. A novel approach to overcome these drawbacks is the use of injectable hydrogels administered intravitreously for sustained drug delivery to the target site. These injectable hydrogels are used as nanocarriers to intimately interact with specific diseased ocular tissues to increase the therapeutic efficacy and drug bioavailability of the anti-glaucomic drugs. The human eye is very delicate, and is sensitive to contact with any foreign body material. However, natural biopolymers are non-reactive, biocompatible, biodegradable, and lack immunogenic and inflammatory responses to the host whenever they are incorporated in drug delivery systems. These favorable biomaterial properties have made them widely applicable in biomedical applications, with minimal adversity. This review highlights the importance of using natural biopolymer-based intravitreal hydrogel drug delivery systems for glaucoma treatment over conventional methods.

Advances in Cellulose-Based Hydrogels for Biomedical Engineering: A Review Summary

In recent years, hydrogel-based research in biomedical engineering has attracted more attention. Cellulose-based hydrogels have become a research hotspot in the field of functional materials because of their outstanding characteristics such as excellent flexibility, stimulus-response, biocompatibility, and degradability. In addition, cellulose-based hydrogel materials exhibit excellent mechanical properties and designable functions through different preparation methods and structure designs, demonstrating huge development potential. In this review, we have systematically summarized sources and types of cellulose and the formation mechanism of the hydrogel. We have reviewed and discussed the recent progress in the development of cellulose-based hydrogels and introduced their applications such as ionic conduction, thermal insulation, and drug delivery. Also, we analyzed and highlighted the trends and opportunities for the further development of cellulose-based hydrogels as emerging materials in the future.

Influence of Viscosity and Thickener on the Effects of Bleaching Gels

OBJECTIVE

This study investigated the influence of the viscosity and kind of thickener of 35% hydrogen peroxide bleaching gels on the tooth (color change, demineralization of enamel, and permeation) and on the gel [reactive oxygen species (ROS), pH, and peroxide concentration].

METHODS AND MATERIALS

Two hundred forty specimens were divided into groups of bleaching gels with different thickeners (CAR, carbomer; ASE, alkali swellable emulsion; MSA, modified sulfonic acid polymer; SSP, semisynthetic polysaccharide; PAC, particulate colloids) in three viscosities (low: 50,000 cP; medium: 250,000 cP; high: 1,000,000 cP). Color change (ΔEab), demineralization of enamel by Knoop microhardness (KHN) reduction analysis, and peroxide permeation (PP) were analyzed in the specimens, while pH, peroxide concentration (PC), and ROS were evaluated in the gels. Data were analyzed by two-way ANOVA (α=0.05).

RESULTS

The higher viscosity gels reduced ΔEab, PP, enamel softening, and ROS in relation to the lower viscosity gels. However, the drop in pH and PC were higher in the more viscous gels. Gels with MSA produced higher ΔEab compared with SSP and ASE. The PP was higher for PAC, and smaller for SSP and CAR. The KHN reduction was higher for CAR and smaller for PAC. The higher pH reduction was seen for ASE and CAR, and the smaller for SSP. The PC reduction was higher for SSP and smaller for CAR. More ROS were observed for MSA and fewer for ASE.

CONCLUSIONS

Increased gel viscosity was associated with reduced color change, permeation, demineralization of enamel, and ROS, and led to increased peroxide decomposition and pH alteration during the treatment. The kind of thickener significantly interfered with the treatment effects.

Recent advances in therapies utilizing superabsorbent hydrogel technology for weight management: A review

Long‐term therapeutic benefit of treatments for weight management in patients with overweight (also termed preobesity) or obesity may be limited by variable safety, tolerability, and efficacy profiles, and patient adherence to treatment regimens. There is a medical need for nonsystemic treatments that promote weight loss in patients with overweight or early obesity. This report reviews four different approaches of utilizing superabsorbent hydrogel technology for weight management at varying stages of preclinical and clinical development. The first is a nonsystemic, oral superabsorbent hydrogel created from naturally derived building blocks used in foods (cellulose‐based), designed to mix homogenously with and change the properties of the ingested meal throughout the gastrointestinal tract (stomach and small intestine). This is the first‐in‐class to be cleared by the Food and Drug Administration (FDA) to aid in weight‐management for adults with BMI of 25–40 kg/m² in conjunction with diet and exercise. In contrast, the other three approaches in development utilize superabsorbent hydrogel technologies to support an intragastric balloon‐like structure, solely occupying space in the stomach and displacing the meal: (1) a pufferfish‐inspired device; (2) Epitomee, a pH‐sensitive self‐expanding hydrogel device; and (3) a light‐degradable hydrogel used to control balloon deflation. These new approaches that utilize superabsorbent hydrogel technology offer a wide range of clinical applicability and have the potential to broaden the weight management treatment landscape. Over time, increasing the number of patients treated with superabsorbent hydrogel technologies will provide important information on long‐term efficacy and safety.

Photo-Crosslinked Hyaluronic Acid/Carboxymethyl Cellulose Composite Hydrogel as a Dural Substitute to Prevent Post-Surgical Adhesion

A dural substitute is frequently used to repair dura mater during neurosurgical procedures. Although autologous or commercially available dural substitutes matched most of the requirements; difficulties during dural repair, including insufficient space for suturing, insufficient mechanical strength, easy tear and cerebrospinal fluid leakage, represent major challenges. To meet this need, a photo-crosslinked hydrogel was developed as a dural substitute/anti-adhesion barrier in this study, which can show sol-to-gel phase transition in situ upon short-time exposure to visible light. For this purpose, hyaluronic acid (HA) and carboxymethyl cellulose (CMC), materials used in abdominal surgery for anti-adhesion purposes, were reacted separately with glycidyl methacrylate to form hyaluronic acid methacrylate (HAMA) and carboxymethyl cellulose methacrylate (CMCMA). The HA/CMC (HC) hydrogels with different HA compositions could be prepared by photo-crosslinking HAMA and CMCMA with a 400 nm light source using lithium phenyl-2,4,6-trimethylbenzoylphosphinate as a photo-initiator. From studies of physico-chemical and biological properties of HC composite hydrogels, they are bio-compatible, bio-degradable and mechanically robust, to be suitable as a dural substitute. By drastically reducing attachment and penetration of adhesion-forming fibroblasts in vitro, the HC hydrogel can also act as an anti-adhesion barrier to prevent adhesion formation after dural repair. From in vivo study in rabbits, the HC hydrogel can repair dural defects as well as protect the dura from post-operative adhesion, endorsing the possible application of this hydrogel as a novel dural substitute.

Viscoelastic and smart swelling disposition of Carboxymethylcellulose based hydrogels substantiated by Gemini surfactant and in-vitro encapsulation and controlled release of Quercetin

CMC-SA-12-E2-12 hydrogels were prepared from Carboxymethylcellulose (CMC), succinic acid (SA) (biocompatible cross-linker) and Ethane-1,2-diyl-bis(N, N-dimethyl-N-dodecylammoniumacetoxy) (referred as 12-E2-12) (0.0006, 0.0015, 0.003, 0.0045 mMoles) by thermal treatment with economical and easy solution polymerization strategy. The CMC-SA-12E2-12 hydrogels were characterized for mechanical and viscoelastic properties like self-healing, viscosity and modulus using rheological analysis. Further the structural, morphological and thermal properties were investigated by FTIR, SEM and TGA analysis. The investigation revealed significant modulation in mechanical, viscoelastic, self-healing and drug release behavior with the addition of 12-E2-12. The CMC-SA-12-E2-12 hydrogels were investigated for drug release studies in PBS 7.4 for 48 h using Quercetin dihydrate. The results showed sustained release behavior at optimised concentration values of surfactant. Release data fitted nicely to the Higuchi model and hence the release could be seen to be diffusion controlled phenomenon or Fickian diffusion. The biocompatibility of cross-linker and surfactant may potentially make the hydrogels suitable for drug delivery applications.

Eco-friendly whey/polysaccharide-based hydrogel with poly(lactic acid) for improvement of agricultural soil quality and plant growth

A set of renewable and biodegradable hydrogels based on acid whey and cellulose derivatives blended with poly(lactic acid) (PLA) were designed as eco-friendly biopolymeric material for sustainable agricultural applications. The physico-chemical properties of the hydrogel were evaluated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and rheological measurements. The effect of the whey/polysaccharide/PLA hydrogel on soil quality improvement (water retention study, biodegradability, loading capacity and release of the fertilizers) and the growth pattern of Raphanus sativus and Phaseolus vulgaris has been also studied. The addition of PLA has been found to improve mechanical properties of the hydrogel. The introduction of 20% wt PLA extended decomposition time of hydrogels by 25% which makes the material more stable in the environment and maintaining the soil humidity for longer. The increasing the amount of PLA led to a rise in hydrogel viscosity brought about better entrapment efficiency of the fertilizers (86-92% for KNO₃ and 87-96% for urea, resp.) compared to control (82% for KNO₃ and 85% for urea, resp.). The novel hydrogels with swelling ratio of up to 500% showed potential as a sustainable water reservoir for plants improving water retention capacity of the soil by 30%.

Natural Polymers in Heart Valve Tissue Engineering: Strategies, Advances and Challenges

In the history of biomedicine and biomedical devices, heart valve manufacturing techniques have undergone a spectacular evolution. However, important limitations in the development and use of these devices are known and heart valve tissue engineering has proven to be the solution to the problems faced by mechanical and prosthetic valves. The new generation of heart valves developed by tissue engineering has the ability to repair, reshape and regenerate cardiac tissue. Achieving a sustainable and functional tissue-engineered heart valve (TEHV) requires deep understanding of the complex interactions that occur among valve cells, the extracellular matrix (ECM) and the mechanical environment. Starting from this idea, the review presents a comprehensive overview related not only to the structural components of the heart valve, such as cells sources, potential materials and scaffolds fabrication, but also to the advances in the development of heart valve replacements. The focus of the review is on the recent achievements concerning the utilization of natural polymers (polysaccharides and proteins) in TEHV; thus, their extensive presentation is provided. In addition, the technological progresses in heart valve tissue engineering (HVTE) are shown, with several inherent challenges and limitations. The available strategies to design, validate and remodel heart valves are discussed in depth by a comparative analysis of in vitro, in vivo (pre-clinical models) and in situ (clinical translation) tissue engineering studies.

Algal Polysaccharides-Based Hydrogels: Extraction, Synthesis, Characterization, and Applications

Hydrogels are three-dimensional crosslinked hydrophilic polymer networks with great potential in drug delivery, tissue engineering, wound dressing, agrochemicals application, food packaging, and cosmetics. However, conventional synthetic polymer hydrogels may be hazardous and have poor biocompatibility and biodegradability. Algal polysaccharides are abundant natural products with biocompatible and biodegradable properties. Polysaccharides and their derivatives also possess unique features such as physicochemical properties, hydrophilicity, mechanical strength, and tunable functionality. As such, algal polysaccharides have been widely exploited as building blocks in the fabrication of polysaccharide-based hydrogels through physical and/or chemical crosslinking. In this review, we discuss the extraction and characterization of polysaccharides derived from algae. This review focuses on recent advances in synthesis and applications of algal polysaccharides-based hydrogels. Additionally, we discuss the techno-economic analyses of chitosan and acrylic acid-based hydrogels, drawing attention to the importance of such analyses for hydrogels. Finally, the future prospects of algal polysaccharides-based hydrogels are outlined.

Polysaccharide-based biopolymer hydrogels for heavy metal detection and adsorption

BACKGROUND

With rapid development in agriculture and industry, water polluted with heavy metallic ions has come to be a serious problem. Adsorption-based methods are simple, efficient, and broadly used to eliminate heavy metals. Conventional adsorption materials have the problems of secondary environmental contamination. Hydrogels are considered effective adsorbents, and those prepared from biopolymers are biocompatible, biodegradable, non-toxic, safe to handle, and increasingly used to adsorb heavy metal ions.

AIM OF REVIEW

The natural origin and easy degradability of biopolymer hydrogels make them potential for development in environmental remediation. Its water absorption capacity enables it to efficiently adsorb various pollutants in the aqueous environment, and its internal pore channels increase the specific surface area for adsorption, which can provide abundant active binding sites for heavy metal ions through chemical modification.

KEY SCIENTIFIC CONCEPT OF REVIEW

As the most representative of biopolymer hydrogels, polysaccharide-based hydrogels are diverse, physically and chemically stable, and can undergo complex chemical modifications to enhance their performance, thus exhibiting superior ability to remove contaminants. This review summarizes the preparation methods of hydrogels, followed by a discussion of the main categories and applications of polysaccharide-based biopolymer hydrogels.

A Comprehensive Assessment on the Pivotal Role of Hydrogels in Scaffold-Based Bioprinting

The past a few decades have seen exponential growth in the field of regenerative medicine. What began as extirpative (complete tissue or organ removal), with little regard to the effects of tissue loss and/or disfigurement, has evolved towards fabricating engineered tissues using personalized living cells (e.g., stem cells), and customizing a matrix or structural organization to support and guide tissue development. Biofabrication, largely accomplished through three-dimensional (3D) printing technology, provides precise, controlled, and layered assemblies of cells and biomaterials, emulating the heterogenous microenvironment of the in vivo tissue architecture. This review provides a concise framework for the bio-manufacturing process and addresses the contributions of hydrogels to biological modeling. The versatility of hydrogels in bioprinting is detailed along with an extensive elaboration of their physical, mechanical, and biological properties, as well as their assets and limitations in bioprinting. The scope of various hydrogels in tissue formation has been discussed through the case studies of biofabricated 3D constructs in order to provide the readers with a glimpse into the barrier-breaking accomplishments of biomedical sciences. In the end, the restraints of bioprinting itself are discussed, accompanied with the identification of available engineering strategies to overcome them.

Thermo-rheological properties of chitosan hydrogels with hydroxypropyl methylcellulose and methylcellulose

Thermal and rheological properties of methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC) hydrogels with chitosan (CHI) were investigated to verify the potential application of these blends as structured systems for oil transport (emulgel, oleogels, and bigels). FTIR confirmed hydrophobic interactions of cellulosic polymers with chitosan. In the temperature sweep, the thermosensitive hydrogels showed their reduced gel point compared to the original polymers. The gelation temperature was reduced from 66.9 °C for pure HPMC to 43.6 °C and 43.6 °C (MC pure polymer) to 39.3 °C when 30% CHI was added for both cases. The addition of 20 and 30% chitosan is enough to modify the extension of the gelation temperature of these polymers. These results indicate that the addition of chitosan enables MC and HPMC to form gels at lower temperatures, which could allow milder thermal conditions to be applied in processing oil carrier systems.

Polymeric Hydrogels for In Vitro 3D Ovarian Cancer Modeling

Ovarian cancer (OC) grows and interacts constantly with a complex microenvironment, in which immune cells, fibroblasts, blood vessels, signal molecules and the extracellular matrix (ECM) coexist. This heterogeneous environment provides structural and biochemical support to the surrounding cells and undergoes constant and dynamic remodeling that actively promotes tumor initiation, progression, and metastasis. Despite the fact that traditional 2D cell culture systems have led to relevant medical advances in cancer research, 3D cell culture models could open new possibilities for the development of an in vitro tumor microenvironment more closely reproducing that observed in vivo. The implementation of materials science and technology into cancer research has enabled significant progress in the study of cancer progression and drug screening, through the development of polymeric scaffold-based 3D models closely recapitulating the physiopathological features of native tumor tissue. This article provides an overview of state-of-the-art in vitro tumor models with a particular focus on 3D OC cell culture in pre-clinical studies. The most representative OC models described in the literature are presented with a focus on hydrogel-based scaffolds, which guarantee soft tissue-like physical properties as well as a suitable 3D microenvironment for cell growth. Hydrogel-forming polymers of either natural or synthetic origin investigated in this context are described by highlighting their source of extraction, physical-chemical properties, and application for 3D ovarian cancer cell culture.

Employing Cellulose Nanofiber-Based Hydrogels for Burn Dressing

The aim of this research was to fabricate a burn dressing in the form of hydrogel films constructed with cellulose nanofibers (CNF) that has pain-relieving properties, in addition to wound healing. In this study, the hydrogels were prepared in the form of film. For this, CNF at weight ratios of 1, 2, and 3 wt.%, 1 wt.% of hydroxyethyl cellulose (HEC), and citric acid (CA) crosslinker with 10 and 20 wt.% were used. FE-SEM analysis showed that the structure of the CNF was preserved after hydrogel preparation. Cationization of CNF by C₆H₁₄NOCl was confirmed by FTIR spectroscopy. The drug release analysis results showed a linear relationship between the amount of absorption and the concentration of the drug. The MTT test (assay protocol for cell viability and proliferation) showed the high effectiveness of cationization of CNF and confirmed the non-toxicity of the resulting hydrogels.

Versatility of Hydrogels: From Synthetic Strategies, Classification, and Properties to Biomedical Applications

Hydrogels are three-dimensional, cross-linked, and supramolecular networks that can absorb significant volumes of water. Hydrogels are one of the most promising biomaterials in the biological and biomedical fields, thanks to their hydrophilic properties, biocompatibility, and wide therapeutic potential. Owing to their nontoxic nature and safe use, they are widely accepted for various biomedical applications such as wound dressing, controlled drug delivery, bone regeneration, tissue engineering, biosensors, and artificial contact lenses. Herein, this review comprises different synthetic strategies for hydrogels and their chemical/physical characteristics, and various analytical, optical, and spectroscopic tools for their characterization are discussed. A range of synthetic approaches is also covered for the synthesis and design of hydrogels. It will also cover biomedical applications such as bone regeneration, tissue engineering, and drug delivery. This review addressed the fundamental, general, and applied features of hydrogels in order to facilitate undergraduates, graduates, biomedical students, and researchers in a variety of domains.

From tissue engineering to mosquitoes: biopolymers as tools for developing a novel biomimetic approach to pest management/vector control

Background

Pest management has been facing the spread of invasive species, insecticide resistance phenomena, and concern for the impact of chemical pesticides on human health and the environment. It has tried to deal with them by developing technically efficient and economically sustainable solutions to complement/replace/improve traditional control methods. The renewal has been mainly directed towards less toxic pesticides or enhancing the precision of their delivery to reduce the volume employed and side effects through lure-and-kill approaches based on semiochemicals attractants. However, one of the main pest management problems is that efficacy depends on the effectiveness of the attractant system, limiting its successful employment to semiochemical stimuli-responsive insects. Biomaterial-based and bioinspired/biomimetic solutions that already guide other disciplines (e.g., medical sciences) in developing precision approaches could be a helpful tool to create attractive new strategies to liberate precision pest management from the need for semiochemical stimuli, simplify their integration with bioinsecticides, and foster the use of still underemployed solutions.

Approach proposed

We propose an innovative approach, called “biomimetic lure-and-kill”. It exploits biomimetic principles and biocompatible/biodegradable biopolymers (e.g., natural hydrogels) to develop new substrates that selectively attract insects by reproducing specific natural environmental conditions (biomimetic lure) and kill them by hosting and delivering a natural biopesticide or through mechanical action. Biomimetic lure-and-kill-designed substrates point to provide a new attractive system to develop/improve and make more cost-competitive new and conventional devices (e.g. traps). A first example application is proposed using the tiger mosquito Aedes albopictus as a model.

Conclusions

Biomaterials, particularly in the hydrogel form, can be a useful tool for developing the biomimetic lure-and-kill approach because they can satisfy multiple needs simultaneously (e.g., biomimetic lure, mechanical lethality, biocompatibility, and bioinsecticide growth). Such an approach might be cost-competitive, and with the potential for applicability to several pest species. Moreover, it is already technically feasible, since all the technologies necessary to design and configure materials with specific characteristics are already available on the market.

Graphical Abstract

Cellulosic-Based Conductive Hydrogels for Electro-Active Tissues: A Review Summary

The use of hydrogel in tissue engineering is not entirely new. In the last six decades, researchers have used hydrogel to develop artificial organs and tissue for the diagnosis of real-life problems and research purposes. Trial and error dominated the first forty years of tissue generation. Nowadays, biomaterials research is constantly progressing in the direction of new materials with expanded capabilities to better meet the current needs. Knowing the biological phenomenon at the interaction among materials and the human body has promoted the development of smart bio-inert and bio-active polymeric materials or devices as a result of vigorous and consistent research. Hydrogels can be tailored to contain properties such as softness, porosity, adequate strength, biodegradability, and a suitable surface for adhesion; they are ideal for use as a scaffold to provide support for cellular attachment and control tissue shapes. Perhaps electrical conductivity in hydrogel polymers promotes the interaction of electrical signals among artificial neurons and simulates the physiological microenvironment of electro-active tissues. This paper presents a review of the current state-of-the-art related to the complete process of conductive hydrogel manufacturing for tissue engineering from cellulosic materials. The essential properties required by hydrogel for electro-active-tissue regeneration are explored after a short overview of hydrogel classification and manufacturing methods. To prepare hydrogel from cellulose, the base material, cellulose, is first synthesized from plant fibers or generated from bacteria, fungi, or animals. The natural chemistry of cellulose and its derivatives in the fabrication of hydrogels is briefly discussed. Thereafter, the current scenario and latest developments of cellulose-based conductive hydrogels for tissue engineering are reviewed with an illustration from the literature. Finally, the pro and cons of conductive hydrogels for tissue engineering are indicated.

Influence of the Operating Conditions on the Release of Corrosion Inhibitors from Spray-Dried Carboxymethylcellulose Microspheres

Sodium carboxymethylcellulose (CMC-Na) microparticles, containing corrosion inhibitor benzotriazole (BTA), were prepared using different spray drying processing parameters, with the purpose of future application in protective coatings for the delivery of corrosion inhibitors. The effects of the processing parameters, such as inlet temperature and spray flow rate, are discussed herein. The biopolymeric CMC-Na microparticles obtained were characterized morphologically by SEM and TEM, and their release profile studied by UV-Vis. The results show that the prepared microparticles (microspheres) were homogeneous, spherically shaped and of a matrix-type nature. Additionally, it was observed that the inlet temperature and spray flow rate significantly influenced the release profiles and process yields. From the different process parameters tested, it was found that the best conditions to achieve higher process yields, higher encapsulation efficiencies and better release properties, were an inlet temperature of 170 °C, a pump rate of 2.5 mL/min, and a drying air-flow rate of 440 L/h.

The latest achievements in plant cellulose-based biomaterials for tissue engineering focusing on skin repair

The present work reviews recent developments in plant cellulose-based biomaterial design and applications, properties, characterizations, and synthesis for skin tissue engineering and wound healing. Cellulose-based biomaterials are promising materials for their remarkable adaptability with three-dimensional polymeric structure. They are capable of mimicking tissue properties, which plays a key role in tissue engineering. Besides, concerns for environmental issues have motivated scientists to move toward eco-friendly materials and natural polymer-based materials for applications in the tissue engineering field these days. Therefore, cellulose as an appropriate substitute for common polymers based on crude coal, animal, and human-derived biomolecules is greatly considered for various applications in biomedical fields. Generally, natural biomaterials lack good mechanical properties for skin tissue engineering. But using modified cellulose-based biopolymers tackles these restrictions and prevents immunogenic responses. Moreover, tissue engineering is a quick promoting field focusing on the generation of novel biomaterials with modified characteristics to improve scaffold function through physical, biochemical, and chemical tailoring. Also, nanocellulose with a broad range of applications, particularly in tissue engineering, advanced wound dressing, and as a material for coupling with drugs and sensorics, has been reviewed here. Moreover, the potential cytotoxicity and immunogenicity of cellulose-based biomaterials are addressed in this review.

Cellulose: A Fascinating Biopolymer for Hydrogel Synthesis

The growing environmental concerns and increasing demands for eco-friendly materials have obliged researchers worldwide to explore naturally occurring biopolymers for various applications. Cellulose is a non-exhaustible polysaccharide biopolymer available almost...

Sprayable Hydrogel for Biomedical Applications

Polymeric hydrogels have extraordinary potential to be utilized for biomedical applications. Recently, sprayable hydrogels have received increasing attention for their biocompatibility, degradability, tunable mechanical properties and rapid spray-filming abilities. In...

Drug Delivery Platforms Containing Thermoresponsive Polymers and Mucoadhesive Cellulose Derivatives: A Review of Patents

Nowadays, the development of mucoadhesive systems for drug delivery has gained keen interest, with enormous potential in applications through different routes. Mucoadhesion characterizes an attractive interaction between the pharmaceutical dosage form and the mucosal surface. Many polymers have shown the ability to interact with mucus, increasing the residence time of local and/or systemic administered preparations, such as tablets, patches, semi-solids, and micro and nanoparticles. Cellulose is the most abundant polymer on the earth. It is widely used in the pharmaceutical industry as an inert pharmaceutical ingredient, mainly in its covalently modified forms: methylcellulose, ethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, and carboxymethylcellulose salts. Aiming to overcome the drawbacks of oral, ocular, nasal, vaginal, and rectal routes and thereby maintaining patient compliance, innovative polymer blends have gained the interest of the pharmaceutical industry. Combining mucoadhesive and thermoresponsive polymers allows for simultaneous in situ gelation and mucoadhesion, thus enhancing the retention of the system at the site of administration and drug availability. Thermoresponsive polymers have the ability to change physicochemical properties triggered by temperature, which is particularly interesting considering the physiological temperature. The present review provides an analysis of the main characteristics and applications of cellulose derivatives as mucoadhesive polymers and their use in blends together with thermoresponsive polymers, aiming at platforms for drug delivery. Patents were reviewed, categorized, and discussed, focusing on the applications and pharmaceutical dosage forms using this innovative strategy. This review manuscript also provides a detailed introduction to the topic and a perspective on further developments.

Modified Synthesis and Physicochemical Characterization of a Bioglass-Based Composite for Guided Bone Regeneration

Objectives

Bioglass composites and polymers are materials of great interest for the medical and dental areas due to their properties, combining the bioactivity of ceramic materials and the mechanical properties of polymers. The purpose of the present study was to develop and to characterize the physicochemical and morphological properties an experimental bioglass-based ternary composite composed associated with sodium carboxymethylcellulose (Na-CMC) and polyvinyl alcohol (PVA). The compatibility of functional groups with bioglass was previously evaluated. The composite was then synthesized and evaluated in terms of morphology, elemental composition, compressive strength, porosity, and bioactivity.

Materials and Methods

The bioglass was previously synthesized using a sol-gel route and characterized using FTIR analysis to identify the functional groups. The bone graft composite was then synthesized associating the bioglass with PVA, surfactant Triton X, and Na-CMC. The composite was then morphologically characterized using SEM/EDS. The porosity of the composite was analyzed using µCT, which also provided the composite compression strength. The composite was then evaluated in terms of its bioactivity using SEM/EDS analyses after immersion in SBF for 12, 24, 48, and 72 h.

Results

FTIR analysis confirmed, among other components, the presence of Si–O–Ca and Si–O–Si bonds, compatible with bioglass. SEM analysis exhibited a composite with a porous structure without spikes. The elemental mapping confirmed the presence of Si, Ca, and P in the composite. µCT analysis demonstrated a porous structure with 42.67% of open pores and an average compression strength of 124.7 MPa. It has also demonstrated ionic changes in the composite surface after immersion in SBF, with increasing detection of Ca and P as a function of time, highlighting its chemical bioactivity.

Conclusions

It can be concluded that the proposed bioglass-based composite presents a three-dimensional, well-structured, chemically bioactive porous structure, mechanically resistant for being reinforced with polymeric phases, with promising results as a synthetic bone graft, which makes it suitable for guided bone regeneration.

Utilization of Cellulose to Its Full Potential: A Review on Cellulose Dissolution, Regeneration, and Applications

As the most abundant natural polymer, cellulose is a prime candidate for the preparation of both sustainable and economically viable polymeric products hitherto predominantly produced from oil-based synthetic polymers. However, the utilization of cellulose to its full potential is constrained by its recalcitrance to chemical processing. Both fundamental and applied aspects of cellulose dissolution remain active areas of research and include mechanistic studies on solvent-cellulose interactions, the development of novel solvents and/or solvent systems, the optimization of dissolution conditions, and the preparation of various cellulose-based materials. In this review, we build on existing knowledge on cellulose dissolution, including the structural characteristics of the polymer that are important for dissolution (molecular weight, crystallinity, and effect of hydrophobic interactions), and evaluate widely used non-derivatizing solvents (sodium hydroxide (NaOH)-based systems, N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl), N-methylmorpholine-N-oxide (NMMO), and ionic liquids). We also cover the subsequent regeneration of cellulose solutions from these solvents into various architectures (fibers, films, membranes, beads, aerogels, and hydrogels) and review uses of these materials in specific applications, such as biomedical, sorption, and energy uses.

Pectin-cellulose hydrogel, silk fibroin and magnesium hydroxide nanoparticles hybrid nanocomposites for biomedical applications

Natural polymers are at the center of materials development for biomedical and biotechnological applications based on their biocompatibility, low-toxicity and biodegradability. In this study, a novel nanobiocomposite based on cross-linked pectin-cellulose hydrogel, silk fibroin, and Mg(OH)₂ nanoparticles was designed and synthesized. After extensive physical-chemical characterization, the biological response of pectin-cellulose/silk fibroin/Mg(OH)₂ nanobiocomposite scaffolds was evaluated by cell viability, red blood cells hemolytic and anti-biofilm assays. After 3 days and 7 days, the cell viability of this nanobiocomposite scaffold was 65.5% and 60.5% respectively. The hemolytic effect was below 20%. Furthermore, the presence of silk fibroin and Mg(OH)₂ nanoparticles allowed to enhance the anti-biofilm activity, inhibiting the P. aeruginosa biofilm formation.

Synthesis and Characterization of Nonwoven Cotton-Reinforced Cellulose Hydrogel for Wound Dressings

Hydrogels wound dressings have enormous advantages due to their ability to absorb high wound exudate, capacity to load drugs, and provide quick pain relief. The use of hydrogels as wound dressings in their original form is a considerable challenge, as these are difficult to apply on wounds without support. Therefore, the incorporation of polymeric hydrogels with a certain substrate is an emerging field of interest. The present study fabricated cellulose hydrogel using the sol-gel technique and reinforced it with nonwoven cotton for sustainable wound dressing application. The nonwoven cotton was immersed inside the prepared solution of cellulose and heated at 50 °C for 2 h to form cellulose hydrogel-nonwoven cotton composites and characterized for a range of properties. In addition, the prepared hydrogel composite was also loaded with titania particles to attain antibacterial properties. The Fourier transform infrared spectroscopy and scanning electron microscopy confirmed the formation of cellulose hydrogel layers inside the nonwoven cotton structure. The fabricated composite hydrogels showed good moisture management and air permeability, which are essential for comfortable wound healing. The wound exudate testing revealed that the fluid absorptive capacity of cellulose hydrogel nonwoven cotton composite was improved significantly in comparison to pure nonwoven cotton. The results reveal the successful hydrogel formation, having excellent absorbing, antimicrobial, and sustainable properties.

An Overview of Cellulose Derivatives-Based Dressings for Wound-Healing Management

Presently, notwithstanding the progress regarding wound-healing management, the treatment of the majority of skin lesions still represents a serious challenge for biomedical and pharmaceutical industries. Thus, the attention of the researchers has turned to the development of novel materials based on cellulose derivatives. Cellulose derivatives are semi-synthetic biopolymers, which exhibit high solubility in water and represent an advantageous alternative to water-insoluble cellulose. These biopolymers possess excellent properties, such as biocompatibility, biodegradability, sustainability, non-toxicity, non-immunogenicity, thermo-gelling behavior, mechanical strength, abundance, low costs, antibacterial effect, and high hydrophilicity. They have an efficient ability to absorb and retain a large quantity of wound exudates in the interstitial sites of their networks and can maintain optimal local moisture. Cellulose derivatives also represent a proper scaffold to incorporate various bioactive agents with beneficial therapeutic effects on skin tissue restoration. Due to these suitable and versatile characteristics, cellulose derivatives are attractive and captivating materials for wound-healing applications. This review presents an extensive overview of recent research regarding promising cellulose derivatives-based materials for the development of multiple biomedical and pharmaceutical applications, such as wound dressings, drug delivery devices, and tissue engineering.

Solvent Mediating the in Situ Self-Assembly of Polysaccharides for 3D Printing Biomimetic Tissue Scaffolds

Intensively studied 3D printing technology is frequently hindered by the effective printable ink preparation method. Herein, we propose an elegant and gentle solvent consumption strategy to slowly disrupt the thermodynamic stability of the biopolymer (polysaccharide: cellulose, chitin, and chitosan) solution to slightly induce the molecule chains to in situ self-assemble into nanostructures for regulating the rheological properties, eventually achieving the acceptable printability. The polysaccharides are dissolved in the alkali/urea solvent. The weak Lewis acid fumed silica (as solvent mediator) is used to (i) slowly and partially consume the alkali/urea solvent to induce the polysaccharide chains to self-assemble into nanofibers to form a percolating network in a limited scale without leading to gelation and (ii) act as the support to increase the solution modulus, for achieving superior printability and scaffold design flexibility. As a demonstration, the resulting polysaccharide scaffolds with biomimetic nanofibrous structures exhibit superior performances in both the cell-free and cell-loaded bone tissue engineering strategies, showing the potential in tissue engineering. Moreover, the fumed silica could be completely removed by alkali treatment without defecting the nanofibrous structure, showing the potential in various applications. We anticipate our solvent-mediated 3D printing ink preparation concept could be used to fabricate other polymeric facile inks and for widespread applications in diverse fields.

A Review of Sustained Drug Release Studies from Nanofiber Hydrogels

Polymer nanofibers have exceptionally high surface area. This is advantageous compared to bulk polymeric structures, as nanofibrils increase the area over which materials can be transported into and out of a system, via diffusion and active transport. On the other hand, since hydrogels possess a degree of flexibility very similar to natural tissue, due to their significant water content, hydrogels made from natural or biodegradable macromolecular systems can even be injectable into the human body. Due to unique interactions with water, hydrogel transport properties can be easily modified and tailored. As a result, combining nanofibers with hydrogels would truly advance biomedical applications of hydrogels, particularly in the area of sustained drug delivery. In fact, certain nanofiber networks can be transformed into hydrogels directly without the need for a hydrogel enclosure. This review discusses recent advances in the fabrication and application of biomedical nanofiber hydrogels with a strong emphasis on drug release. Most of the drug release studies and recent advances have so far focused on self-gelling nanofiber systems made from peptides or other natural proteins loaded with cancer drugs. Secondly, polysaccharide nanofiber hydrogels are being investigated, and thirdly, electrospun biodegradable polymer networks embedded in polysaccharide-based hydrogels are becoming increasingly popular. This review shows that a major outcome from these works is that nanofiber hydrogels can maintain drug release rates exceeding a few days, even extending into months, which is an extremely difficult task to achieve without the nanofiber texture. This review also demonstrates that some publications still lack careful rheological studies on nanofiber hydrogels; however, rheological properties of hydrogels can influence cell function, mechano-transduction, and cellular interactions such as growth, migration, adhesion, proliferation, differentiation, and morphology. Nanofiber hydrogel rheology becomes even more critical for 3D or 4D printable systems that should maintain sustained drug delivery rates.

Biofabrication of skin tissue constructs using alginate, gelatin and diethylaminoethyl cellulose bioink

INTRODUCTION

Biofabrication of skin tissue equivalents using 3D bioprinting technology has gained much attention in recent times due to the simplicity, the versatility of the technology and its ability in bioengineering biomimetic tissue histology. The key component being the bioink, several groups are actively working on the development of various bioink formulations for optimal skin tissue construction.

METHODS

Here, we present alginate (ALG), gelatin (GEL) and diethylaminoethyl cellulose (DCEL) based bioink formulation and its application in bioprinting and biofabrication of skin tissue equivalents. Briefly, DEAE cellulose powder was dispersed in alginate solution with constant stirring at 60 °C to obtain a uniform distribution of cellulose fibers; this was then mixed with GEL solution to prepare the bioink. The formulation was systematically characterized for its morphological, physical, chemical, rheological, biodegradation and biocompatibility properties. The printability, shape fidelity and cell-laden printing were assessed using the CellInk bioprinter.

RESULTS

The bioink proved to be a good printable, non-cytotoxic and stable hydrogel formulation. The primary human fibroblast and keratinocyte-loaded 3D bioprinted constructs showed excellent cell viability, collagen synthesis, skin-specific marker and biomimetic tissue histology.

CONCLUSION

The results demonstrated the successful formulation of ALG-GEL-DCEL bioink and its application in the development of human skin tissue equivalents with distinct epidermal-dermal histological features.