Preparation and characterization of injectable self-antibacterial gelatin/carrageenan/bacterial cellulose hydrogel scaffolds for wound healing application

Fabrication of Thymol-loaded Isabgol/Konjac Glucomannan-based Microporous Scaffolds with Enriched Antioxidant and Antibacterial Properties for Skin Tissue Engineering Applications

An antioxidant, antibacterial, and biocompatible biomaterial is essential to repair skin wounds effectively. Here, we have employed two natural biopolymers, isabgol (ISAB) and konjac glucomannan (KGM), to prepare microporous scaffolds by freezing and lyophilization. The scaffolds are loaded with thymol (THY) to impart potent antioxidant and antibacterial activities. The physicochemical properties of the ISAB+KGM+THY scaffold, like porosity (41.8±2.4 %), swelling, and biodegradation, were optimal for tissue regeneration application. Compared to the control, ISAB+KGM+THY scaffolds promote attachment, migration, and proliferation of L929 fibroblasts. The antioxidant activity of the ISAB+KGM+THY scaffold was significantly improved after loading THY. This would protect the tissues from oxidative damage. The antibacterial activity of the ISAB+KGM+THY scaffold was significantly higher than that of the control, which would help prevent bacterial infection. The vascularization ability of the ISAB+KGM scaffold was not altered by incorporating THY in the ISAB+KGM scaffold. Therefore, a strong antioxidant, antibacterial, and biocompatible nature of the ISAB+KGM+THY scaffold could be useful for various biomedical applications.

Injectable Carrageenan/Green Graphene Oxide Hydrogel: A Comprehensive Analysis of Mechanical, Rheological, and Biocompatibility Properties

In this work, physically crosslinked injectable hydrogels based on carrageenan, locust bean gum, and gelatin, and mechanically nano-reinforced with green graphene oxide (GO), were developed to address the challenge of finding materials with a good balance between injectability and mechanical properties. The effect of GO content on the rheological and mechanical properties, injectability, swelling behavior, and biocompatibility of the nanocomposite hydrogels was studied. The hydrogels' morphology, assessed by FE-SEM, showed a homogeneous porous architecture separated by thin walls for all the GO loadings investigated. The rheology measurements evidence that G' > G″ over the whole frequency range, indicating the dominant elastic nature of the hydrogels and the difference between G' over G″ depends on the GO content. The GO incorporation into the biopolymer network enhanced the mechanical properties (ca. 20%) without appreciable change in the injectability of the nanocomposite hydrogels, demonstrating the success of the approach described in this work. In addition, the injectable hydrogels with GO loadings ≤0.05% w/v exhibit negligible toxicity for 3T3-L1 fibroblasts. However, it is noted that loadings over 0.25% w/v may affect the cell proliferation rate. Therefore, the nano-reinforced injectable hybrid hydrogels reported here, developed with a fully sustainable approach, have a promising future as potential materials for use in tissue repair.

Nanocellulose-based platforms as a multipurpose carrier for drug and bioactive compounds: From active packaging to transdermal and anticancer applications

The nanocellulose has unique characteristics, such as biocompatibility, good mechanical strength, and low cytotoxicity. The nanocellulose crystalline portion is responsible for good mechanical resistance, while the amorphous portion is responsible for flexibility. Such features make it a promising candidate for multiple applications related to the modulation of substance release: targeted cancer therapy, transdermal drug delivery, and controlled-release packaging materials. Thus, in this study, we discussed nanocellulose as a multipurpose material for drug delivery and bioactive compound carriers in controlled delivery systems with varied applications in pharmaceutic fields. Herein, we focus on understanding key factors such as i) polymer-drug interactions and surface modification strategies in controlled release rates, ii) therapeutic efficacy, and iii) biocompatibility aspects. The tunable chemistry surface plays a fundamental approach limiting the quick release of active substances in drug delivery systems. Several works on a pre-clinical stage of investigation were overviewed, reporting robust evidence on nanocellulose to design bioactive compounds/drug delivery carriers based on stimuli-responsive drug release and controlled delivery systems for higher efficiency in cancer therapies, purposing target therapy and reduced side effects. Nanocellulose was also identified as a solid candidate material in active packaging for pharmaceutical products. Cellulose nanocrystals and bacterial cellulose demonstrated strong potential to overcome the challenge of controlled release profile and open novel insights in advanced active packaging materials for pharmaceutics with controlled release of antioxidant and antimicrobial substances. Moreover, the concept overview in this work might be extended in active food packaging technologies to flavor-releasing/absorbing systems or antimicrobial/antioxidant carriers for extending the shelf life of foods.

Advancements in gelatin-based hydrogel systems for biomedical applications: A state-of-the-art review

A gelatin-based hydrogel system is a stimulus-responsive, biocompatible, and biodegradable polymeric system with solid-like rheology that entangles moisture in its porous network that gradually protrudes to assemble a hierarchical crosslinked arrangement. The hydrolysis of collagen directs gelatin construction, which retains arginyl glycyl aspartic acid and matrix metalloproteinase-sensitive degeneration sites, further confining access to chemicals entangled within the gel (e.g., cell encapsulation), modulating the release of encapsulated payloads and providing mechanical signals to the adjoining cells. The utilization of various types of functional tunable biopolymers as scaffold materials in hydrogels has become highly attractive due to their higher porosity and mechanical ability; thus, higher loading of proteins, peptides, therapeutic molecules, etc., can be further modulated. Furthermore, a stimulus-mediated gelatin-based hydrogel with an impaired concentration of gellan demonstrated great shear thinning and self-recovering characteristics in biomedical and tissue engineering applications. Therefore, this contemporary review presents a concise version of the gelatin-based hydrogel as a conceivable biomaterial for various biomedical applications. In addition, the article has recapped the multiple sources of gelatin and their structural characteristics concerning stimulating hydrogel development and delivery approaches of therapeutic molecules (e.g., proteins, peptides, genes, drugs, etc.), existing challenges, and overcoming designs, particularly from drug delivery perspectives.

Polysaccharide based transdermal patches for chronic wound healing: Recent advances and clinical perspective

Polysaccharides form a major class of natural polymers with diverse applications in biomedical science and tissue engineering. One of the key thrust areas for polysaccharide materials is skin tissue engineering and regeneration, whose market is estimated to reach around 31 billion USD globally by 2030, with a compounded annual growth rate of 10.46 %. Out of this, chronic wound healing and management is a major concern, especially for underdeveloped and developing nations, mainly due to poor access to medical interventions for such societies. Polysaccharide materials have shown promising results and clinical potential in recent decades with regard to chronic wound healing. Their low cost, ease of fabrication, biodegradability, and ability to form hydrogels make them ideal candidates for managing and healing such difficult-to-heal wounds. The present review presents a summary of the recently explored polysaccharide-based transdermal patches for managing and healing chronic wounds. Their efficacy and potency of healing both as active and passive wound dressings are evaluated in several in-vitro and in-vivo models. Finally, their clinical performances and future challenges are summarized to draw a road map towards their role in advanced wound care.

Wound Dressing Double-Crosslinked Quick Self-Healing Hydrogel Based on Carboxymethyl Chitosan and Modified Nanocellulose

The use of hydrogels in wound dressings, which is pivotal for effective wound treatment, has been widely applied to diverse medical wound conditions. However, formulating natural hydrogels that combine robust strength and self-healing capabilities is a significant challenge. To overcome this, we successfully designed a natural nanocellulose self-healing hydrogel that can quickly self-heal and restore the complete hydrogel structure after injury to fill the injured area and protect the wound from external damage. Our study utilized modified natural polymer carboxymethyl chitosan (CMC), hydrazide-modified carboxymethyl cellulose nanofibers (HCNF), and cellulose nanocrystals modified by dialdehyde (DACNC) to fabricate the hydrogel. The amides containing more amino groups and HCNF in CMC can be used as cross-linking nodes, and the high aspect ratio and specific surface area of DACNC are favorable for the connection of many active hydrogels. The hydrogel is crosslinked by the dynamic imide bond and hydrazone bond between the amino group of CMC, the amide of HCNF, and the aldehyde of DACNC and has a double network structure. These connections can be readily reassembled when disrupted, enabling fast self-healing of hydrogels within five minutes. Moreover, HCNF and DACNC were incorporated as nano-reinforced fillers to bolster the hydrogel's strength while preserving its high liquid absorption capacity (381% equilibrium swelling rate).

Biodegradable Polymers and Polymer Composites with Antibacterial Properties

Antibiotic resistance is one of the greatest threats to global health and food security today. It becomes increasingly difficult to treat infectious disorders because antibiotics, even the newest ones, are becoming less and less effective. One of the ways taken in the Global Plan of Action announced at the World Health Assembly in May 2015 is to ensure the prevention and treatment of infectious diseases. In order to do so, attempts are made to develop new antimicrobial therapeutics, including biomaterials with antibacterial activity, such as polycationic polymers, polypeptides, and polymeric systems, to provide non-antibiotic therapeutic agents, such as selected biologically active nanoparticles and chemical compounds. Another key issue is preventing food from contamination by developing antibacterial packaging materials, particularly based on degradable polymers and biocomposites. This review, in a cross-sectional way, describes the most significant research activities conducted in recent years in the field of the development of polymeric materials and polymer composites with antibacterial properties. We particularly focus on natural polymers, i.e., polysaccharides and polypeptides, which present a mechanism for combating many highly pathogenic microorganisms. We also attempt to use this knowledge to obtain synthetic polymers with similar antibacterial activity.

Preparation of porous PCL-PEG-PCL scaffolds using supercritical carbon dioxide

In this study, the Supercritical Carbon Dioxide (scCO₂) gas foaming procedure was used in the preparation of scaffolds containing the model drug dexamethasone (DXMT). The method used did not include an organic solvent thus making it a safe method. The ring-opening polymerization of PCL-PEG-PCL (PCEC) triblock was conducted using an organocatalyst [1,8 diazabicyclo [5.4.0] undec-7-ene (DBU)]. After mixing 5.0 g of DXMT with 50.0 g of PCEC, hydraulic pressure was applied to compress the mixed powder into disc-like tablets. The tablet-like scaffold of the triblock containing DXMT was inserted into a scCO₂ gas-foaming device. The peak porosity percentage of the synthesized triblock was found to be 55.58 %. Pressure, temperature, soaking time and the time required to depressurize were recorded as 198 bar, 50 °C, 2.0 h, and 28 min respectively. After treatment with scCO₂, the scaffolds experienced an almost full release of DXMT in vitro after 30 days (83.74 ± 1.54 % vs 52.24 ± 2.03 % before scCO₂ treatment). In conclusion, the results proved that the scCO₂ gas foaming procedure could be employed for constructing modifiable PCEC scaffolds with plausible porosity and structural and morphological features which can manipulate drug release.

Preparation of thyme oil loaded κ-carrageenan-polyethylene glycol hydrogel membranes as wound care system

The present study is aimed at fabricating thyme oil loaded hydrogel membranes composed of κ-carrageenan (CG) and polyethylene glycol (PEG), which can provide moist environment and prevent infections for rapid wound healing. Membranes were prepared with different amounts of PEG via solvent casting technique under ambient conditions. Physicochemical properties of CG-PEG membranes as a function of the PEG content were investigated. The surface morphology of membranes displayed smoother surfaces with increasing PEG content up to 40%. In addition, the interaction of PEG with CG polymer chains was evaluated in terms of Free and bound PEG fraction within the membrane matrix. Furthermore, thyme oil (TO) was added to enhance the antibacterial properties of CG-PEG membranes. These membranes showed >95% antimicrobial activity against both gram-positive and gram-negative bacteria depending on the TO content. Suggesting the great potential of these membranes as a strong candidate for providing an effective antimicrobial nature in human healthcare.

Bioactive Carbohydrate Polymers-Between Myth and Reality

Polysaccharides are complex macromolecules long regarded as energetic storage resources or as components of plant and fungal cell walls. They have also been described as plant mucilages or microbial exopolysaccharides. The development of glycosciences has led to a partial and difficult deciphering of their other biological functions in living organisms. The objectives of glycobiochemistry and glycobiology are currently to correlate some structural features of polysaccharides with some biological responses in the producing organisms or in another one. In this context, the literature focusing on bioactive polysaccharides has increased exponentially during the last two decades, being sometimes very optimistic for some new applications of bioactive polysaccharides, notably in the medical field. Therefore, this review aims to examine bioactive polysaccharide, taking a critical look of the different biological activities reported by authors and the reality of the market. It focuses also on the chemical, biochemical, enzymatic, and physical modifications of these biopolymers to optimize their potential as bioactive agents.

Comparison of drug release behavior of bacterial cellulose loaded with ibuprofen and propranolol hydrochloride

The aim of this study was to investigate the drug release behavior from bacterial cellulose (BC). Ibuprofen and propranolol hydrochloride were used as model drugs to represent low and highly water soluble drugs. The drug was loaded into the BC by immersing the partially swollen BC in a solution of drug concentrations ranging from 0.05 to 0.5 mg mL-1 and then drying by two different methods: air-drying and freeze-drying. The results showed that the type of drug and the drying method influenced the drug loading efficiency and drug release behavior. For ibuprofen, high drug loading efficiency was found when loading the drug into BC at low concentration and vice versa for propranolol hydrochloride. The drug-loaded BC prepared by the freeze-drying method showed a sustained release regardless of drug type and drug-loaded amount. The sustained release followed the Higuchi and Korsmeyer-Peppas models. On the other hand, when using the air-drying method, BC loaded with ibuprofen showed immediate release at every drug-loaded amount. However, BC loaded with propranolol hydrochloride showed immediate release at the high drug-loaded amount but showed sustained release at the low drug-loaded amount. The release of drug from a drug-loaded BC prepared by air-drying method tended to follow first-order kinetics. In conclusion, the drug loading concentration and the drying method in the drug-loaded BC preparation influenced the drug release characteristics of the BC-based drug delivery system.

Development of dual crosslinked mumio-based hydrogel dressing for wound healing application: Physico-chemistry and antimicrobial activity

In this study, an antimicrobial mumio-based hydrogel dressing was developed for wound healing application. The mechanism of gel formation was achieved via a double crosslink network formation between gelatin (GT) and polyvinyl alcohol (PVA) using polyethylene glycol diglycidyl ether (PEGDE) and borax as crosslinking agents. To enhance the mechanical integrity of the hydrogel matrix, bacterial cellulose (BC) was integrated into the GT-PVA hydrogel to produce a composite gel dressing. The obtained hydrogel was characterized by FTIR, SEM, TGA, and XRD. Gel fraction, in vitro swelling and degradation as well as compressive modulus properties of the gel dressing were investigated as a function of change in PVA and BC ratios. By increasing the ratios of PVA and BC, the composite dressing showed lower swelling but higher mechanical strength. Comparing to other formulations, the gel with 4 %w/v PVA and 1 %w/v BC demonstrated to be most suitable in terms of stability and mechanical properties. In vitro cell cytotoxicity by MTT assay on human alveolar basal epithelial (A549) cell lines validated the gels as non-toxic. In addition, the mumio-based gel was compared to other formulations containing different bioactive agents of beeswax and cinnamon oil, which were tested for microbial growth inhibition effects against different bacteria (S. aureus and K. pneumoniae) and fungi (C. albicans and A. niger) strains. Results suggested that the gel dressing containing combinations of mumio, beeswax and cinnamon oil possess promising future in the inhibition of microbial infection supporting its application as a suitable dressing for wound healing.