Characteristics of antimicrobial fibers prepared with wood periodate oxycellulose

Bacterial cellulose-based hydrogel with regulated rehydration and enhanced antibacterial activity for wound healing

Bacterial cellulose (BC) hydrogels are promising medical biomaterials that have been widely used for tissue repair, wound healing and cartilage engineering. However, the high water content of BC hydrogels increases the difficulty of storage and transportation. Moreover, they will lose their original hydrogel structure after dehydration, which severely limits their practical applications. Introducing the bio-based polyelectrolytes is expected to solve this problem. Here, we modified BC and combined it with quaternized chitosan (QCS) via a chemical reaction to obtain a dehydrated dialdehyde bacterial cellulose/quaternized chitosan (DBC/QCS) hydrogel with repeated swelling behavior and good antibacterial properties. The hydrogel can recover the initial state on the macro scale with a swelling ratio over 1000 % and possesses excellent antimicrobial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) with a killing rate of 80.8 % and 81.3 %, respectively. In addition, the hydrogel has excellent biocompatibility, which is conducive to the stretching of L929 cells. After 14 d of in vivo wound modeling in rats, it was found that the hydrogel loaded with pirfenidone (PFD) could promote collagen deposition and accelerate wound healing with scar prevention. This rehydratable hydrogel can be stored and transported under dry conditions, which is promising for practical applications.

Antimicrobial and hydrophobic cellulose paper prepared by covalently attaching cinnamaldehyde for strawberries preservation

The demand for paper-based packaging materials as an alternative to incumbent disposable petroleum-derived polymers for food packaging applications is ever-growing. However, typical paper-based formats are not suitable for use in unconventional applications due to inherent limitations (e.g., excessive hydrophilicity, lack antimicrobial ability), and accordingly, enabling new capabilities is necessity. Herein, a simple and environmentally friendly strategy was proposed to introduce antimicrobial and hydrophobic functions to cellulose paper through successive chemical grafting of 3-aminopropyltriethoxysilane (APS) and cinnamaldehyde (CA). The results revealed that cellulose paper not only showed long-term antibacterial effect on different bacteria, but also inhibited a wide range of fungi. Encouragingly, the modified paper, which is fluorine-free, displays a high contact angle of 119.7°. Thus, even in the wet state, the modified paper can still maintain good mechanical strength. Meanwhile, the multifunctional composite papers have excellent biocompatibility and biodegradability. Compared with ordinary cellulose paper, multifunctional composite paper can effectively prolong the shelf life of strawberries. Therefore, the multifunctional composite paper represents good application potential as a fruit packaging material.

Injectable, In Situ Self-cross-linking, Self-healing Poly(l-glutamic acid)/Polyethylene Glycol Hydrogels for Cartilage Tissue Engineering

Injectable hydrogels have drawn much attention in the field of tissue engineering because of advantages such as simple operation, strong plasticity, and good biocompatibility and biodegradability. Herein, we propose the novel design of injectable hydrogels via a Schiff base cross-linking reaction between adipic dihydrazide (ADH)-modified poly(l-glutamic acid) (PLGA-ADH) and benzaldehyde-terminated poly(ethylene glycol) (PEG-CHO). The effects of the mass fraction and the molar ratio of -CHO/-NH₂ on the gelation time, mechanical properties, equilibrium swelling, and in vitro degradation of the hydrogels were examined. The PLGA/PEG hydrogels cross-linked by dynamic Schiff base linkages exhibited good self-healing ability. Additionally, the PLGA/PEG hydrogels had good biocompatibility with bone marrow-derived mesenchymal stem cells (BMSCs) and could effectively support BMSC proliferation and deposition of glycosaminoglycans and upregulate the expression of cartilage-specific genes. In a rat cartilage defect model, PLGA/PEG hydrogels significantly promoted new cartilage formation. The results suggest the prospect of the PLGA/PEG hydrogels in cartilage tissue engineering.

pH-Universal Catechol-Amine Chemistry for Versatile Hyaluronic Acid Bioadhesives

Catechol, a major mussel-inspired underwater adhesive moiety, has been used to develop functional adhesive hydrogels for biomedical applications. However, oxidative catechol chemistry for interpolymer crosslinking and adhesion is exclusively effective under alkaline conditions, with limited applications in non-alkaline conditions. To overcome this limitation, pH-universal catechol-amine chemistry to recapitulate naturally occurring biochemical events induced by pH variation in the mussel foot is suggested. Aldehyde moieties are introduced to hyaluronic acid (HA) by partial oxidation, which enables dual-mode catechol tethering to the HA via both stable amide and reactive secondary amine bonds. Because of the presence of additional reactive amine groups, the resultant aldehyde-modified HA conjugated with catechol (AH-CA) is effectively crosslinked in acidic and neutral pH conditions. The AH-CA hydrogel exhibits not only fast gelation via active crosslinking regardless of pH conditions, but also strong adhesion and excellent biocompatibility. The hydrogel enables rapid and robust wound sealing and hemostasis in neutral and alkaline conditions. The hydrogel also mediates effective therapeutic stem cell and drug delivery even in dynamic and harsh environments, such as a motile heart and acidic stomach. Therefore, the AH-CA hydrogel can serve as a versatile biomaterial in a wide range of pH conditions in vivo.

A self-healing hydrogel based on oxidized microcrystalline cellulose and carboxymethyl chitosan as wound dressing material

As the food processing by-products, hericium erinaceus residues (HER) and pineapple peel (PP) are good sources of cellulose and chitosan that can be prepared into hydrogels for structuring a drug delivery system. Hydrogel is one new type biomaterial for drug delivery with excellent absorbent ability applied in wound dressing. In this research, one composite self-healing hydrogel with pH sensitivity for drug delivery system based on the Schiff-base reaction was fabricated. Therein aldehyde group of oxidized microcrystalline cellulose (OMCC) from PP were crosslinked with amino group of carboxymethyl chitosan (CMCS) from HER via Schiff-base reaction for structuring hydrogels. The structures of the prepared hydrogels were characterized. Meanwhile, its blood clotting activity and physical properties were investigated. The hydrogels show some favorable performances with suitable gel time (54 s of minimum), distinguish swelling rate (about 31.18 g/g), good mechanical, self-healing characteristic and well coagulation effect. The cumulative release of the rutin-loaded hydrogel OMCM-54 reached about 80 % within 6 h, suggesting the well-controlled release of rutin by crosslinking degree between the modified OMCC and CMCS based on Schiff-base reaction. The novel biomaterial based on hericium erinaceus residues and pineapple peel shows its potential use as wound dressing.

Bacterial cellulose reinforced chitosan-based hydrogel with highly efficient self-healing and enhanced antibacterial activity for wound healing

Biocompatible hydrogels with versatile functions are highly desired for demanding the complicated tissue issues, including irregular site and motional wound. Herein, a bio-based hydrogel with multifunctional properties is designed based on quaternized chitosan and dialdehyde bacterial cellulose. As a functional wound dressing, the hydrogel shows rapid self-healing performance and injectable behaviors due to dynamic Schiff-base interactions and presents superior antibacterial activity against E. coli (gram-negative) and S. aureus (gram-positive). The constructed 3D hydrogel also exhibits proper compressive property, desired water retention capacity. To be mentioned, the hydrogel could mimic the structure of natural extracellular matrix (ECM) in the presence of bacterial cellulose nanofibers. Thus, the biopolymer-based hydrogel shows good biocompatibility in terms of cell proliferation and cell spreading. The prepared chitosan-based hydrogel with self-healing, antibacterial, and low cost will become a promising biomaterial for wound healing.

Cellulose-Based Nanomaterials Advance Biomedicine: A Review

There are various biomaterials, but none fulfills all requirements. Cellulose biopolymers have advanced biomedicine to satisfy high market demand and circumvent many ecological concerns. This review aims to present an overview of cellulose knowledge and technical biomedical applications such as antibacterial agents, antifouling, wound healing, drug delivery, tissue engineering, and bone regeneration. It includes an extensive bibliography of recent research findings from fundamental and applied investigations. Cellulose-based materials are tailorable to obtain suitable chemical, mechanical, and physical properties required for biomedical applications. The chemical structure of cellulose allows modifications and simple conjugation with several materials, including nanoparticles, without tedious efforts. They render the applications cheap, biocompatible, biodegradable, and easy to shape and process.

Antimicrobial and physicochemical characterization of 2,3-dialdehyde cellulose-based wound dressings systems

Biobased and biodegradable films were prepared by physically mixing 2,3-dialdehyde cellulose (DAC) with two other biopolymers, zein and gelatin, in three different proportions. The antimicrobial activities of the composite blends against Gram-positive and Gram-negative bacteria increase with the increase of DAC content. Cell viability tests on mammalian cells showed that the materials were not cytotoxic. In addition, DAC and gelatin were able to promote thermal degradation of the blends. However, DAC increased the stiffness and decreased the glass transition temperature of the blends, while gelatin was able to decrease the stiffness of the film. Morphological analysis showed the effect of DAC on the surface smoothness of the blends. The contact angle confirmed that all blends were within the range of hydrophilic materials. Although all the blends showed impressive performance for wound dressing application, the blend with gelatin might be more suitable for this purpose due to its better mechanical performance and antibacterial activity.

Asymmetric wetting and antibacterial composite membrane obtained by spraying bacterial cellulose grafted with chitosan for sanitary products surface layers

The asymmetric wetting membranes have attracted intense attention in liquid directional transportation. However, it is a huge challenge to prepare surface layer membrane for sanitary products with antibacterial and asymmetric wettability by a simple method. Herein, the bacterial cellulose grafted with chitosan (BC-CS) was used as the hydrophilic agent to modify polypropylene nonwoven fabric (PPF) substrate via easy and effective one-sided layer-by-layer spraying to prepare the asymmetric wetting and antibacterial composite membrane (BC-CS/PPF). It showed that the BC-CS/PPF had good physical properties, which was attributed to the strong and uniform physical combination between nano-sized BC-CS and PPF. The sanitary products with BC-CS/PPF surface layer, denoted as BC-CS/PPF sanitary products, also had good absorption and anti-return property. The antibacterial test revealed that BC-CS had an excellent performance against S. aureus and E. coli in the simulated application environment. Moreover, the antibacterial performance was better than that of commercial sanitary products.

Simple Way for Ag-NPs Preparation based on Starch Macromolecule

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Finding a sustainable, inexpensive way for Ag-NPs synthesis is considered as one of the most important requirements for industrial application. Oxidized starch was prepared using sodium periodate. Oxidized starch (DAS) was characterized by measuring aldehyde content and using FTIR spectroscopy. DAS was used as reducing and stabilizing agent for the preparation of Ag nanoparticles (Ag-NPs). Factors that may affect the preparation of Ag-NPs include pH, AgNO3/DAS molar ratio, temperature and time were studied. UV-Vis. spectroscopy and particle size analysis showed that DAS can act as reducing and stabilizing agent for the preparation of Ag-NPs and the mean particle size was 19 nm. The so prepared AgNPs were used as antibacterial agent for cotton fabric using the pad dry cure method. The results of antibacterial test showed that the presence of Ag-NPs enhanced the antibacterial properties of the treated cotton fabrics.

Dialdehyde modified cellulose nanofibers enhanced the physical properties of decorative paper impregnated by aldehyde-free adhesive

Impregnated decorative paper was an important wood-based panel finishing material. However, traditional impregnated decorative paper was impregnated with melamine-formaldehyde resin, which will release formaldehyde and harm the human health. To solve this problem, small molecule polyacrylate-polyethylene glycol (PEG) adhesive was used to achieve the non-formaldehyde addition of the impregnation system. The dialdehyde modified CNF (D-CNF), modified by sodium periodate (NaIO₄), and triethylenediamine were introduced to enhance the surface properties of the impregnated decorative paper. The results showed that the incorporation of D-CNF and triethylenediamine imparted excellent physical strength and surface properties to impregnated decorative paper. When the dosage of 0.3 wt% D-CNF and 3 mL/100 g triethylenediamine in the compound emulsion, the hardness, abrasion resistant value and surface bonding strength of impregnated decorative paper adhered fiberboard reached 3H, 330 r of damage and 1.13 MPa, respectively. Thus, it could be effectively used for making high-performance formaldehyde-free impregnated decorative paper.

Antibacterial modification of Lyocell fiber: A review

As the most successful regenerated cellulose fiber developed in recent decades, Lyocell has attracted much attention due to its useful properties, simple manufacturing process, and recyclable solvent. However, Lyocell's lack of antibacterial properties limits its application in medical and health fields. Antibacterial modification of Lyocell fiber can be achieved by three general approaches: physical blending, chemical reaction, and post-treatment. Physical blending methods introduce antibacterial agents directly into the spinning dope. In chemical reaction methods, functional groups of the antibacterial additives are grafted or crosslinked into Lyocell fibers, thereby imparting antimicrobial properties. In post-treatment methods, antibacterial additives are deposited on Lyocell fiber surfaces by physical coating, padding, or impregnation processes. We organize our review of antibacterial modification of Lyocell fibers by these preparation methods. Some of the modified Lyocell fibers are reported to exhibit improved antimicrobial activity against various bacteria and fungi, indicating promise for application in medical or hygienic products.

Transparent, Flexible, and Strong 2,3-Dialdehyde Cellulose Films with High Oxygen Barrier Properties

2,3-Dialdehyde cellulose (DAC) of a high degree of oxidation (92% relative to AGU units) prepared by oxidation of microcrystalline cellulose with sodium periodate (48 °C, 19 h) is soluble in hot water. Solution casting, slow air drying, hot pressing, and reinforcement by cellulose nanocrystals afforded films (∼100 μm thickness) that feature intriguing properties: they have very smooth surfaces (SEM), are highly flexible, and have good light transmittance for both the visible and near-infrared range (89–91%), high tensile strength (81–122 MPa), and modulus of elasticity (3.4–4.0 GPa) depending on hydration state and respective water content. The extraordinarily low oxygen permeation of <0.005 cm³ μm m^–2 day^–1 kPa^–1 (50% RH) and <0.03 cm³ μm m^–2 day^–1 kPa^–1 (80% RH) can be regarded as a particularly interesting feature of DAC films. The unusually high initial contact angle of about 67° revealed a rather low hydrophilicity compared to other oxidatively modified or unmodified cellulosic materials which is most likely the result of inter- and intramolecular hemiacetal and hemialdal formation during drying and pressing.

A Reloadable Self-Healing Hydrogel Enabling Diffusive Transport of C-Dots Across Gel-Gel Interface for Scavenging Reactive Oxygen Species

While reloadable drug delivery platforms are highly prized for the treatment of a broad spectrum of diseases, the gel-gel interface between hydrogels hinders the intergel diffusive transport of drugs and thus limits the application of hydrogels as reloadable depots. Here, this study reports the circumvention of this barrier by employing a self-healing hydrogel prepared from N-carboxyethyl chitosan and sodium alginate dialdehyde, which are cross-linked via a reversible Schiff base linkage. The injectable and bioadhesive hydrogel shows a rapid gelation time of 47 s. The dynamic self-healing process enables the efficient diffusive transport of carbon quantum dots (C-dots) into an adjacent hydrogel, and thus, the C-dots can be used to scavenge reactive oxygen species from a remote inflammation site. Specifically, the diffusive transport of the C-dots in the self-healing hydrogel after three sequential reloading steps is sevenfold greater than that in the non-self-healing counterpart. In vivo, hematoxylin and eosin staining of the murine skin at the injection site shows no apparent symptoms of inflammation in the group treated with the reloadable self-healing hydrogel. The current strategy represents a promising and straightforward route for the design of a reloadable drug delivery system for future use in clinical application.

Water-soluble cationic poly(β-cyclodextrin-co-guanidine) as a controlled vitamin B2delivery carrier

Vitamin B₂(VB₂) is effectively incorporated into novel water-soluble cationic β-cyclodextrin (β-CD) polymers in order to improve its physiochemical properties.

Injectable in situ self-cross-linking hydrogels based on poly(L-glutamic acid) and alginate for cartilage tissue engineering

Injectable hydrogels as an important biomaterial class have been widely used in regenerative medicine. A series of injectable poly(l-glutamic acid)/alginate (PLGA/ALG) hydrogels were fabricated by self-cross-linking of hydrazide-modified poly(l-glutamic acid) (PLGA-ADH) and aldehyde-modified alginate (ALG-CHO). Both the degree of PLGA modification and the oxidation degree of ALG-CHO could be adjusted by the amount of activators and sodium periodate, respectively. The effect of the solid content of the hydrogels and oxidation degree of ALG-CHO on the gelation time, equilibrium swelling, mechanical properties, microscopic morphology, and in vitro degradation of the hydrogels was examined. Encapsulation of rabbit chondrocytes within hydrogels showed viability of the entrapped cells and good biocompatibility of the injectable hydrogels. A preliminary study exhibited injectability and rapid in vivo gel formation, as well as mechanical stability, cell ingrowth, and ectopic cartilage formation. The injectable PLGA/ALG hydrogels demonstrated attractive properties for future application in a variety of pharmaceutical delivery and tissue engineering, especially in cartilage tissue engineering.

Preparation of microfibrillated cellulose/chitosan-benzalkonium chloride biocomposite for enhancing antibacterium and strength of sodium alginate films

The nonantibacterial and low strength properties of sodium alginate films negatively impact their application for food packaging. In order to improve these properties, a novel chitosan-benzalkonium chloride (C-BC) complex was prepared by ionic gelation using tripolyphosphate (TPP) as a coagulant, and a biocomposite obtained through the adsorption of C-BC complex on microfibrillated cellulose, MFC/C-BC, was then incorporated into a sodium alginate film. The TEM image showed that the C-BC nanoparticles were spherical in shape with a diameter of about 30 nm, and the adsorption equilibrium time of these nanoparticles on the surface of MFC was estimated to be 6 min under the driving forces of hydrogen bonds and electrostatic interactions. According to the disc diffusion method, the MFC/C-BC biocomposite-incorporated sodium alginate film exhibited remarkable antibacterial activity against Staphylococcus aureus and certain antibacterial activity against Escherichia coli . The strength tests indicated that the tensile strength of the composite sodium alginate film increased about 225% when the loading of MFC/C-BC biocomposite was 10 wt %. These results suggested that the MFC/C-BC biocomposite-incorporated sodium alginate film with excellent antibacterial and strength properties would be a promising material for food packaging, and the MFC/C-BC may also be a potential multifunctional biocomposite for other biodegradable materials.