Is Dialdehyde Chitosan a Good Substance to Modify Physicochemical Properties of Biopolymeric Materials?

Tobramycin crosslinking improves the colloidal stability of arginine chitosan biodynamers for safe and efficient siRNA delivery

We previously reported proteoid biodynamers to form dynamic nanocomplexes (dynaplexes, DPs) with siRNA and their efficient transfection via dynamic responsive changes in endosomal environments. However, their limited colloidal stability requires chemical crosslinking, which may cause toxicity. To address these limitations, we designed biodynamers using positively charged aldehyde chitosan (ACh) as the backbone, which was functionalized with arginine hydrazide (Arg) and/or tobramycin (Tob) to create either Arg-ACh, Tob-ACh or Arg/Tob-ACh, respectively. While the additional positive charges introduced by Arg improved the siRNA complexation, the multiple amine groups in Tob acted as internal crosslinkers. Additionally, the resulting siRNA-loaded DPs were coated with hyaluronic acid (HA), which further enhanced colloidal stability. Compared to proteoid biodynamers, these novel functionalized chitosan biodynamers provided adequate gene silencing efficiency without the need for potentially harmful additional crosslinkers.

A review of bio-based dialdehyde polysaccharides as multifunctional building blocks for biomedical and food science applications

Food science and biomedical engineering are key disciplines related to human health, with the development of functional materials being an important research direction in both fields. In recent years, dialdehyde polysaccharides (DAPs), as green biopolymers, have become increasingly important in functional materials within food science and biomedical engineering. This work systematically summarizes the sources and properties of various DAPs, introduces their preparation methods and common DAP-based functional biomaterials, including hydrogels, scaffolds, films, coatings, nanoparticles, and nanofibers. Importantly, this work also reviews DAP applications in functional materials for food science and biomedical engineering, such as drug delivery, wound dressings, tissue engineering, food packaging films/edible coatings, food emulsions, antibacterial nanoparticles, and enzyme immobilization. Finally, the work briefly discusses the biosafety of DAPs. To conclude, this study provides a toolkit for developing functional materials in these fields and offers important reference value regarding the broad application of DAPs.

Cross-Linking Agents in Three-Component Materials Dedicated to Biomedical Applications: A Review

In biomaterials research, using one or two components to prepare materials is common. However, there is a growing interest in developing materials composed of three components, as these can offer enhanced physicochemical properties compared to those consisting of one or two components. The introduction of a third component can significantly improve the mechanical strength, biocompatibility, and functionality of the resulting materials. Cross-linking is often employed to further enhance these properties, with chemical cross-linking agents being the most widely used method. This article provides an overview of the chemical agents utilized in the cross-linking of three-component biomaterials. The literature review focused on cases where the material was composed of three components and a chemical substance was employed as the cross-linking agent. The most commonly used cross-linking agents identified in the literature include glyoxal, glutaraldehyde, dialdehyde starch, dialdehyde chitosan, and the EDC/NHS mixture. Additionally, the review briefly discusses materials cross-linked with the MES/EDC mixture, caffeic acid, tannic acid, and genipin. Through a critical analysis of current research, this work aims to guide the development of more effective and safer biopolymeric materials tailored for biomedical applications, highlighting potential areas for further investigation and optimization.

Gelatin-Sodium Alginate Hydrogels Cross-Linked by Squaric Acid and Dialdehyde Starch as a Potential Bio-Ink

Hydrogels as biomaterials possess appropriate physicochemical and mechanical properties that enable the formation of a three-dimensional, stable structure used in tissue engineering and 3D printing. The integrity of the hydrogel composition is due to the presence of covalent or noncovalent cross-linking bonds. Using various cross-linking methods and agents is crucial for adjusting the properties of the hydrogel to specific biomedical applications, e.g., for direct bioprinting. The research subject was mixtures of gel-forming polymers: sodium alginate and gelatin. The polymers were cross-linked ionically with the addition of CaCl2 solutions of various concentrations (10%, 5%, 2.5%, and 1%) and covalently using squaric acid (SQ) and dialdehyde starch (DAS). Initially, the polymer mixture's composition and the hydrogel cross-linking procedure were determined. The obtained materials were characterized by mechanical property tests, swelling degree, FTIR, SEM, thermal analysis, and biological research. It was found that the tensile strength of hydrogels cross-linked with 1% and 2.5% CaCl2 solutions was higher than after using a 10% solution (130 kPa and 80 kPa, respectively), and at the same time, the elongation at break increased (to 75%), and the stiffness decreased (Young Modulus is 169 kPa and 104 kPa, respectively). Moreover, lowering the concentration of the CaCl2 solution from 10% to 1% reduced the final material's toxicity. The hydrogels cross-linked with 1% CaCl2 showed lower degradation temperatures and higher weight losses than those cross-linked with 2.5% CaCl2 and therefore were less thermally stable. Additional cross-linking using SQ and DAS had only a minor effect on the strength of the hydrogels, but especially the use of 1% DAS increased the material's elasticity. All tested hydrogels possess a 3D porous structure, with pores of irregular shape and heterogenic size, and their swelling degree initially increased sharply to the value of approx. 1000% during the first 6 h, and finally, it stabilized at a level of 1200-1600% after 24 h. The viscosity of 6% gelatin and 2% alginate solutions with and without cross-linking agents was similar, and they were only slightly shear-thinning. It was concluded that a mixture containing 2% sodium alginate and 6% gelatin presented optimal properties after gel formation and lowering the concentration of the CaCl2 solution to 1% improved the hydrogel's biocompatibility and positively influenced the cross-linking efficiency. Moreover, chemical cross-linking by DAS or SQ additionally improved the final hydrogel's properties and the mixture's printability. In conclusion, among the tested systems, the cross-linking of 6% gelatin-2% alginate mixtures by 1% DAS addition and 1% CaCl2 solution is optimal for tissue engineering applications and potentially suitable for 3D printing.

In vitro and in silico approach towards antimicrobial and antioxidant behaviour of water-soluble chitosan dialdehyde biopolymers

Chitosan dialdehyde (ChDA) was prepared from a three-step process initiated by thermal organic acid hydrolysis, periodate oxidization, and precipitation from native chitosan (NCh). The developed ChDA resulted in an aldehydic content of about 82 % with increased solubility (89 %) and maximum yield (97 %). The functional alteration of the aldehydic (-CHO) group in ChDA was established using vibrational stretching at 1744 cm-1. The increase in the zone of inhibition of ChDA compared to NCh has confirmed the inherent antimicrobial effect against bacterial and fungal species. ChDA showed better antioxidant activity of about 97.4 % (DPPH) and 31.1 % (ABTS) compared to NCh, measuring 45.3 % (DPPH) and 15.9 % (ABTS), respectively. The novel insilico predictions of the ChDA's biocidal activity were confirmed through molecular docking studies. The amino acid moiety such as ARG 110 (A), ASN 206 (A), SER 208 (A), THR 117 (B), ASN 118 (B), and LYS 198 (B) residues of 7B53 peptide from E. coli represents the binding pockets responsible for interaction with aldehyde group of ChDA. Whereas PHE 115 (E), ALA 127 (H), TYR 119 (C), GLN 125 (H), ASN 175 (E), ARG 116 (E), LYS 101 (H), and LYS 129 (H) of 1IYL A peptide from Candida albicans makes possible for binding with ChDA. Hence, the synergistic effect of ChDA as a biocidal compound is found to be plausible in the drug delivery system for therapeutic applications.

Preparation of novel and recyclable chitosan-alumina nanocomposite as superabsorbent to remove diazinon and tetracycline contaminants from aqueous solution

This work presents a novel, strong and efficient adsorbent (CS@TDI@EDTA@γ-AlO(OH)) prepared through the green process using three components, chitosan, BNPs and EDTA using amide and ester bridges. An eco-friendly and easy approach was used for the preparation of this novel adsorbent, the low cost, easy access to the used materials, and the simplicity of the preparation method are some of the interesting advantages of this work. Also, this prepared adsorbent was used as an adsorbent to remove diazinon organophosphate poison and tetracycline antibiotic from aqueous solutions. In order to confirm the prepared adsorbent structure, the CS@TDI@EDTA@γ-AlO(OH) composite was investigated by various analyses including FT-IR, EDX, XRD, FESEM and TGA. The adsorption behavior of the adsorbent prepared for the removal of tetracycline and diazinon was investigated under different conditions by varying the concentration, temperature, the adsorbent dose, pH and contact time. Based on various tests, the highest diazinon adsorption capacity was obtained for 0.12 g/L adsorbent at pH 7 and 60 °C with 40 mg/L initial concentration. Also, the maximum adsorption capacity of the tetracycline was obtained for 0.12 g/L adsorbent at pH 9 and 60 °C with 30 mg/L initial concentration. The equilibrium results for diazinon and for tetracycline were in good accordance with the Langmuir and Freundlich isotherm models, respectively. Also, the highest adsorption capacities for diazinon at pH 7 and tetracycline at pH 9 were 1428.5 and 555.5 mg/g, respectively. Also the kinetic investigations revealed that the correlation factor (R2) of pseudo-second-order model obtained for the adsorption of diazinon and tetracycline was 0.9986 and 0.9988, while the coefficient k (g/mg.min) was 0.000084 and 0.0033, respectively. These results indicate that the adsorption of diazinon and tetracycline is pseudo-second-order kinetics model. Formation of hydrogen bonds between adsorbate and adsorbent as well as the high specific surface area and porosity of the adsorbent are the main mechanisms that contribute to the adsorption process. In addition, thermodynamic studies indicated that the adsorption of diazinon and tetracycline is a spontaneous endothermic process. The adsorbent prepared in this work was expected to have wide range of applications in wastewater treatment thanks to its good reusability in water and strong removal of diazinon and tetracycline compared to other adsorbents.

Effects of proanthocyanidins and dialdehyde chitosan on the proliferation and differentiation of bovine myoblast for cultured meat production

Cultured meat technology intends to manufacture meat by cultivating muscle stem cells in vitro, which is an emerging methodology in meat production. However, the insufficient stemness of bovine myoblasts cultivated in vitro declined the ability of cell expansion and myogenic differentiation, which limited the production of cultured meat. Therefore, in this study, we introduced proanthocyanidins (PC, natural polyphenolic compounds) and dialdehyde chitosan (DAC, natural polysaccharides) to explore the effects of proliferation and differentiation of bovine myoblasts in vitro. The experiment results revealed that PC and DAC promoted cell proliferation by improving the transition from G1 to the S phase as well as cell division in G2. Meanwhile, the myogenic differentiation of cells was further boosted by the combined PC and DAC up-regulation of MYH3 expression. Moreover, the study revealed the synergistic effect of PC and DAC on enhancing the structural stability of collagen, and bovine myoblasts demonstrated excellent growth and dispersion ability on collagen scaffolds. It is concluded that both PC and DAC promote the proliferation and differentiation of bovine myoblasts, contributing to the development of cultured meat production systems.

Robust cross-linked cyclodextrin glucanotransferase from Bacillus lehensis G1 aggregates using an improved cross-linker and a new co-aggregant for the production of cyclodextrins

One of the potentials of carrier-free cross-linked enzyme aggregates (CLEA) immobilization is the ability to be separated and reuse. Yet, it might be impeded by the poor mechanical stability resulting low recyclability. CLEA of CGTase from Bacillus lehensis G1 (CGTase G1-CLEA) using chitosan (CS) as a cross-linker demonstrated high activity recovery however, displayed poor reusability. Therefore, the relationship between mechanical strength and reusability is studied by enhancing the CS mechanical properties and applying a new co-aggregation approach. Herein, CS was chemically cross-linked with glutaraldehyde (GA) and GA was introduced as a co-aggregant (coGA). CGTase G1-CLEA developed using an improved synthesized chitosan-glutaraldehyde (CSGA) cross-linker and a new coGA technique showed to increase its mechanical stability which retained 63.4% and 52.2%, respectively compared to using CS that remained 33.1% of their initial activity after stirred at 500 rpm. The addition of GA impacted the morphology and interaction consequently stabilizing the CLEAs durability in production of cyclodextrins. As a result, the reusability of CGTase G1-CLEA with CSGA and coGA increased by 56.6% and 42.8%, respectively compared to previous CLEA after 5 cycles for 2 h of reaction. This verifies that the mechanical strength of immobilized enzyme influences the improvement of its operational stability.

Nature-Inspired Heat and Moisture Exchanger Filters Composed of Gelatin and Chitosan for the Design of Eco-Sustainable "Artificial Noses"

For long-term mechanical ventilation, during anesthesia or intensive care, it is crucial to preserve a minimum level of humidity to avoid damage to the respiratory epithelium. Heat and moisture exchange filters (HME), also called "artificial noses," are passive systems that contribute to delivering inspired gases at about the same conditions of healthy respiration, i.e., 32 °C and relative humidity higher than 90%. Current HME devices suffer from limitations linked either to performance and filtration efficiency to their inadequate antibacterial efficiency, sterilization methods, and durability. Furthermore, in times of global warming and diminishing petroleum oil reserves, replacing the employing of synthetic materials with biomass biodegradable raw materials has considerable economic and environmental value. In the present study, a generation of eco-sustainable, bioinspired, and biodegradable HME devices are designed and developed through a green-chemistry process based on raw materials deriving from food waste and taking inspiration from the functioning, structure, and chemistry of our respiratory system. In particular, different blends are obtained by mixing aqueous solutions of gelatin and chitosan in various polymer ratios and concentrations and then by cross-linking them with different low amounts of genipin, a natural chemical cross-linker. Finally, the blends, post-gelation, are freeze-dried to obtain three-dimensional (3D) highly porous aerogels reproducing both the highly exposed surface area of the upper respiratory ways and the chemical composition of the mucus secretion covering the nasal mucosae. Results are comparable with accepted standards for HME devices and suitable bacteriostatic potential, thus validating these bioinspired materials as promising candidates to be used as an eco-sustainable generation of HME devices.

Biomedical applications of chitosan/silk fibroin composites: A review

Natural polymers have been used in the biomedical fields for decades, mainly derived from animals and plants with high similarities with biomacromolecules in the human body. As an alkaline polysaccharide, chitosan (CS) attracts much attention in tissue regeneration and drug delivery with favorable biocompatibility, biodegradation, and antibacterial activity. However, to overcome its mechanical properties and degradation behavior drawbacks, a robust fibrous protein-silk fibroin (SF) was introduced to prepare the CS/SF composites. Not only can CS be combined with SF via the amide and hydrogen bond formation, but also their functions are complementary and tunable with the blending ratio. To further improve the performances of CS/SF composites, natural (e.g., hyaluronic acid and collagen) and synthetic biopolymers (e.g., polyvinyl alcohol and hexanone) were incorporated. Also, the CS/SF composites acted as slow-release carriers for inorganic non-metals (e.g., hydroxyapatite and graphene) and metal particles (e.g., silver and magnesium), which could enhance cell functions, facilitate tissue healing, and inhibit bacterial growth. This review presents the state-of-the-art and future perspectives of different biomaterials combined with CS/SF composites as sponges, hydrogels, membranes, particles, and coatings. Emphasis is devoted to the biological potentialities of these hybrid systems, which look rather promising toward a multitude of applications.

The influence of molecular weight of cellulose on the properties of carboxylic acid crosslinked cellulose hydrogels for biomedical and environmental applications

Hydrogels a three-dimensional network structure of hydrophilic polymers have gained significant interest in the field of biomedicine due to its high-water absorption properties and its resemblance to native extracellular matrix. However, the hydrogel's physicochemical properties are important in its ability to serve as a matrix in biomedical applications. The variations on the molecular weight of polymers on the preparation of crosslinked hydrogels may alter the properties. Different molecular weight carboxymethyl cellulose polymers were employed in this work to determine the effect of molecular weight on the physicochemical parameters of the hydrogel's crosslinking reaction. For this study, two distinct molecular weight carboxymethyl cellulose (CMC) polymers (M_w, 250,000 and 700,000) and various concentrations of crosslinker solution were used. The hydrogels were prepared through a chemical crosslinking reaction combining CMC and citric acid, which results in the formation of an ester bond between the two polymer chains. The crosslinking reaction is confirmed by Fourier transform infrared spectroscopy and total carboxyl content analysis. According to the physicochemical, thermal, and mechanical analysis, we have identified that 7 %, 9 % and 10 % citric acid showed the most promising hydrogels and found 7CMC hydrogel had superior quality. In vitro results demonstrated that the citric acid crosslinked CMC had excellent hemocompatibility and cytocompatibility.

The Characterization of Scaffolds Based on Dialdehyde Chitosan/Hyaluronic Acid

In this work, two-component dialdehyde chitosan/hyaluronic acid scaffolds were developed and characterized. Dialdehyde chitosan was obtained by one-step synthesis with chitosan and sodium periodate. Three-dimensional scaffolds were prepared by the lyophilization method. Fourier transform infrared spectroscopy (FTIR) was used to observe the chemical structure of scaffolds and scanning electron microscopy (SEM) imaging was done to assess the microstructure of resultant materials. Thermal analysis, mechanical properties measurements, density, porosity and water content measurements were used to characterize physicochemical properties of dialdehyde chitosan/hyaluronic acid 3D materials. Additionally, human epidermal keratinocytes (NHEK), dermal fibroblasts (NHDF) and human melanoma cells (A375 and G-361) were used to evaluate cell viability in the presence of subjected scaffolds. It was found that scaffolds were characterized by a porous structure with interconnected pores. The scaffold composition has an influence on physicochemical properties, such as mechanical strength, thermal resistance, porosity and water content. There were no significant differences between cell viability proliferation of all scaffolds, and this observation was visible for all subjected cell lines.

Lipid-Polymeric Films: Composition, Production and Applications in Wound Healing and Skin Repair

The use of lipids in the composition of polymeric-based films for topical administration of bioactive ingredients is a recent research topic; while few products are commercially available, films containing lipids represent a strategic area for the development of new products. Some lipids are usually used in polymeric-based film formulations due to their plasticizing action, with a view to improving the mechanical properties of these films. On the other hand, many lipids have healing, antimicrobial, anti-inflammatory, anti-aging properties, among others, that make them even more interesting for application in the medical-pharmaceutical field. This manuscript discusses the production methods of these films both on a laboratory and at industrial scales, the properties of the developed biopolymers, and their advantages for the development of dermatologic and cosmetic products.

Medicated Hydroxyapatite/Collagen Hybrid Scaffolds for Bone Regeneration and Local Antimicrobial Therapy to Prevent Bone Infections

Microbial infections occurring during bone surgical treatment, the cause of osteomyelitis and implant failures, are still an open challenge in orthopedics. Conventional therapies are often ineffective and associated with serious side effects due to the amount of drugs administered by systemic routes. In this study, a medicated osteoinductive and bioresorbable bone graft was designed and investigated for its ability to control antibiotic drug release in situ. This represents an ideal solution for the eradication or prevention of infection, while simultaneously repairing bone defects. Vancomycin hydrochloride and gentamicin sulfate, here considered for testing, were loaded into a previously developed and largely investigated hybrid bone-mimetic scaffold made of collagen fibers biomineralized with magnesium doped-hydroxyapatite (MgHA/Coll), which in the last ten years has widely demonstrated its effective potential in bone tissue regeneration. Here, we have explored whether it can be used as a controlled local delivery system for antibiotic drugs. An easy loading method was selected in order to be reproducible, quickly, in the operating room. The maintenance of the antibacterial efficiency of the released drugs and the biosafety of medicated scaffolds were assessed with microbiological and in vitro tests, which demonstrated that the MgHA/Coll scaffolds were safe and effective as a local delivery system for an extended duration therapy—promising results for the prevention of bone defect-related infections in orthopedic surgeries.