Zwitterionic choline phosphate functionalized chitosan with antibacterial property and superior water solubility

Preparation, characterization and antibacterial investigation of water-soluble curcumin-chitooligosaccharide complexes

Curcumin has a wide range of application prospects, with various bioactivities in the food industry and in the biomedical field. However, curcumin has poor water solubility and is sensitive to pH, light and temperature. In this study, curcumin-chitooligosaccharide (CUR-COS) complexes were prepared via mechanochemical methods, and the CUR-COS complex was more soluble after freeze-drying (up to 862-fold greater than that of curcumin). The complex was characterized by SEM, XRD, FT-IR and thermal analysis, and its stability against pH, light and thermal treatment was evaluated. COSs could serve as carriers for curcumin delivery. Additionally, the antibacterial activity of the formed complex was determined. As a result, CUR-COS exhibited significantly better water solubility, enhanced stability, and stronger antibacterial properties than did pure CUR, offering a promising pathway for the extensive application of lipophilic natural products in foods, especially water-based products.

Bioactive metabolites identification of the foxnut and broken millet-based nutritional bar using HR-MS

The by-products of the grain processing industry are a vital resource for the valorization methods in the food industry. In comparison to the whole grain, the broken kernels and seeds own similar nutrient and bioactive compounds having multifaceted health properties. This study aims to develop a nutritional bar by utilizing the by-products from barnyard millet and foxnut with added sweeteners. Furthermore, high-resolution mass spectrometry (HR-MS) metabolomics was carried out in positive and negative both ion modes to identify the major bioactive compounds formed in the matrix of the best-optimized valorized bar. The formulation of the bar having 15 % foxnut flour and the barnyard flour each, was elucidated highest rheological and sensory scores. A sum of 29 bioactive metabolites has been observed in the obtained metabolome. Major metabolites were palmitoyl serinol, glycitein, persin, bufagargarizin, apigenin, carvone, etc. covering a wide area in the mass spectrum. The therapeutic value of these compounds is heart health promotion, anti-inflammatory, anti-carcinogenic, anti-diabetic, anti-microbial, etc. This work highlights the bioactivity of the valorized nutritional bar employing robust and accurate tool of mass spectrometry. The developed snack is a functional food for the consumers.

Novel biomimetic macromolecules system for highly efficient lubrication, ROS scavenging and osteoarthritis treatment

The early stages of osteoarthritis (OA) in the joints are typically characterized by two key factors: the dysfunction of articular cartilage lubrication and inflammation resulting from the excessive production of reactive oxygen species (ROS). Synthetic injectable macromolecular materials present great potential for preventing the progression of early OA. In this study, to mimic the excellent lubricity of brush-like aggregates found in natural synovial fluid, we develop a novel macromolecular biolubricant (CS-PS-DA) by integrating adhesion and hydration groups onto backbone of natural biomacromolecules. CS-PS-DA exhibits a strong affinity for cartilage surfaces, enabling the formation of a stable lubrication layer at the sliding interface of degraded cartilages to restore joint lubrication performance. In vitro results from ROS scavenging and anti-inflammatory experiments indicate the great advantage of CS-PS-DA to decrease the levels of proinflammatory cytokines by inhibiting ROS overproduction. Finally, in vivo rats OA model demonstrates that intra-cavitary injection of CS-PS-DA could effectively resist cartilage wear and mitigated inflammation in the joints. This novel biolubricant provides a new and timely strategy for the treatment of OA.

Thermoresponsive in situ forming and self-healing double-network hydrogels as injectable dressings for silymarin/levofloxacin delivery for treatment of third-degree burn wounds

Our study aimed to introduce a novel double-cross-linked and thermoresponsive hydrogel with remarkable potential for accelerating third-degree burn wound healing. Burn injuries are recognized as challenging, critical wounds. Especially in third-degree burns, treatment is demanding due to extended wounds, irregular shapes, significant exudation, and intense pain during dressing changes. In this work, hydrogels made of zwitterionic chitosan and dialdehyde starch (ZCS and ZDAS) were created to deliver silymarine (SM) and levofloxacin (LEV). The hydrogels were effortlessly produced using dynamic Schiff base linkages and ionic interactions between ZCS and ZDAS at appropriate times. The pore uniformity, gel fraction, and commendable swelling properties can imply a suitable degree of Schiff base cross-link. The hydrogel demonstrated outstanding shape retention, and significant self-healing and flexibility abilities, enabling it to uphold its form even during bodily movements. After injecting biocompatible hydrogel on the wound, a notable acceleration in wound closure was observed on day 21 (98.1 ± 1.10 %) compared to the control group (75.1 ± 6.13 %), and histopathological analysis revealed a reduction of inflammation that can be linked to remarkable antioxidant and antibiotic properties. The results demonstrate the hydrogel's efficacy in promoting burn wound healing, making it a promising candidate for medical applications.

Quaternary-ammonium chitosan, a promising packaging material in the food industry

Quaternary-ammonium chitosan (QAC) is a polysaccharide with good water solubility, bacteriostasis, and biocompatibility. QAC is obtained by methylating or grafting the quaternary-ammonium group of chitosan and is an important compound in the food industry. Various QAC-based complexes have been prepared using reversible intermolecular interactions, such as electrostatic interactions, hydrogen bonding, metal coordination, host-guest interactions, and covalent bonding interactions consisting of Schiff base bonding and dynamic chemical bond cross-linking. In the food industry, QAC is often used as a substrate in film or coating for food preservation and as a carrier for active substances to improve the encapsulation efficiency and storage stability of functional food ingredients. In this review, we have assimilated the latest information on QAC to facilitate further discussions and future research. Advancement in research on QAC would contribute toward technology acceleration and its increased contribution to the field of food technology.

A Self-Healable and Recyclable Zwitterionic Polyurethane Based on Dynamic Ionic Interactions

Polyurethanes with self-healing and reprocessing capabilities are promising in eco-friendly applications. Here, a self-healable and recyclable zwitterionic polyurethane (ZPU) was developed by introducing ionic bonds between protonated ammonium groups and sulfonic acid moieties. The structure of the synthesized ZPU was characterized by FTIR and XPS. The thermal, mechanical, self-healing and recyclable properties of ZPU were also investigated in detail. Compared with cationic polyurethane (CPU), ZPU shows similar thermal stability. The physical cross-linking network formed between zwitterion groups can dissipate strain energy as a weak dynamic bond, endowing ZPU with outstanding mechanical and elastic recovery properties, including the high tensile strength of 7.38 MPa, high elongation at a break of 980%, and fast elastic recovery ability. Additionally, ZPU exhibits a healing efficiency of over 93% at 50 °C for 1.5 h as a result of the dynamic reconstruction of reversible ionic bonds. Furthermore, ZPU can be well reprocessed by solution casting and hot-pressing with a recovery efficiency above 88%. The excellent mechanical properties, fast repairing capability, and good recyclability not only enable polyurethane with a promising application in protective coatings for textiles and paints but also make it a superior candidate as stretchable substrates for wearable electronic devices and strain sensors.

Chitosan-Urushiol nanofiber membrane with enhanced acid resistance and broad-spectrum antibacterial activity

Due to the large specific surface area and rich pore structure, chitosan nanofiber membrane has many advantages over conventional gel-like or film-like products. However, the poor stability in acidic solutions and relatively weak antibacterial activity against Gram-negative bacteria severely restrict its use in many industries. Here, we present a chitosan-urushiol composite nanofiber membrane prepared by electrospinning. Chemical and morphology characterization revealed that the formation of chitosan-urushiol composite involved the Schiff base reaction between catechol and amine groups and the self-polymerization of urushiol. The unique crosslinked structure and multiple antibacterial mechanisms endowed the chitosan-urushiol membrane with outstanding acid resistance and antibacterial performance. After immersion in HCl solution at pH 1, the membrane maintained its intact appearance and satisfactory mechanical strength. In addition to its good antibacterial performance against Gram-positive Staphylococcus aureus (S. aureus), the chitosan-urushiol membrane exhibited synergistic antibacterial activity against Gram-negative Escherichia coli (E. coli) that far exceeded that of neat chitosan membrane and urushiol. Moreover, cytotoxicity and hemolysis assays revealed that the composite membrane had good biocompatibility similar to that of neat chitosan. In short, this work provides a convenient, safe, and environmentally friendly method to simultaneously enhance the acid resistance and broad-spectrum antibacterial activity of chitosan nanofiber membranes.

A Choline Phosphoryl-Conjugated Chitosan/Oxidized Dextran Injectable Self-Healing Hydrogel for Improved Hemostatic Efficacy

The development of injectable hydrogels with good biocompatibility, self-healing, and superior hemostatic properties is highly desirable in emergency and clinical applications. Herein, we report an in situ injectable and self-healing hemostatic hydrogel based on choline phosphoryl functionalized chitosan (CS-g-CP) and oxidized dextran (ODex). The CP groups were hypothesized to accelerate hemostasis by facilitating erythrocyte adhesion and aggregation. Our results reveal that the CS-g-CP/ODex hydrogels exhibit enhanced blood clotting and erythrocyte adhesion/aggregation capacities compared to those of the CS/ODex hydrogels. The CS-g-CP₅₀/ODex₇₅ hydrogel presents rapid gelation time, good mechanical strength and tissue adhesiveness, satisfactory bursting pressure, and favorable biocompatibility. The hemostatic ability of the CS-g-CP₅₀/ODex₇₅ hydrogel was significantly improved compared to that of the CS/ODex hydrogel and commercial fibrin sealant in the rat tail amputation and liver/spleen injury models. Our study highlights the positive and synergistic effects of CP groups on hemostasis and strongly supports the CS-g-CP₅₀/ODex₇₅ hydrogel as a promising adhesive for hemorrhage control.

Biomimetic chitosan-derived bifunctional lubricant with superior antibacterial and hydration lubrication performances

The lubrication deficiency in joints is a major cause of osteoarthritis. One of the most commonly used treatment means is to inject artificial lubricants, but there is a potential risk of infection during the injection process. Therefore, developing artificial lubricants with dual functions of friction-reduction and antibacterial is urgent. In this work, a novel polysaccharide-derived lubricant with simultaneous anti-bacteria and water-lubrication properties, called CS-MPC-N, is developed by grafting 2‑methacryloyloxylethyl phosphorylcholine (MPC) and nisin peptide onto backbone of chitosan (CS). Compared to the control CS, CS-MPC-N exhibits good lubrication and friction-reduction properties because of its excellent water solubility. Especially, CS-MPC-N shows low friction coefficient (0.03 ∼ 0.05) at the sliding interfaces of artificial joints materials or even natural articular cartilages. Moreover, CS-MPC-N can effectively inhibit the proliferation of Staphylococcus aureu, exhibiting excellent antibacterial effect. This kind of novel polysaccharide-derived lubricant is expected to be used in treating infectious arthritis.

Zwitterionic choline phosphate conjugated folate-poly (ethylene glycol): a general decoration of erythrocyte membrane-coated nanoparticles for enhanced tumor-targeting drug delivery

Erythrocyte membrane nanosystems have become one of the important research directions of disease treatment, especially for tumor treatment, and can enhance the long circulation time of anti-cancer drugs in vivo, and penetrate and accumulate in the tumor site effectively. However, erythrocyte membranes lack targeting properties and it is necessary to provide tumor-targeting function by modifying erythrocyte membranes. In this study, we report on a novel modification method of an erythrocyte membrane nanosystem to target tumors. Specifically, the tumor-targeting molecule folate-poly (ethylene glycol) (FA-PEG) was modified with a zwitterionic 2-(methyl acryloyoxy) ethyl choline phosphate (MCP) by the Michael addition reaction to obtain MCP-modified FA-PEG (MCP-PEG-FA). Based on the strong "N-P" tetravalent electrostatic interaction between MCP and phosphatidyl choline on the erythrocyte membranes, MCP-PEG-FA can be modified on the erythrocyte membrane encapsulated doxorubicin (DOX) loaded poly(lactic-co-glycolic acid) (PLGA) nanosystem to form a tumor-targeting erythrocyte membrane nanosystem (FA-RBC@PLGA-DOX). The results show that MCP-PEG-FA was synthesized and successfully bonded to the erythrocyte membrane nanosystem, and the FA-RBC@PLGA-DOX nanosystem had a better tumor-targeting function and tumor killing effect compared with those of the nanosystems without FA ligand modification. The universal modification method of erythrocyte membranes is successfully provided and can be applied to the treatment of various diseases.

Characteristics of chitosan fiber and their effects towards improvement of antibacterial activity

We selected eight kinds of chitosan fibers to characterize and analyze their composition, surface morphology, and mechanical properties. Crucially, we investigated their antibacterial activity against Escherichia coli, Staphylococcus aureus and Candida albicans and the dependence on the molecular weight (Mw) and the degree of deacetylation (DD). On that basis, the relationship between antibacterial activity and Mw and DD can be established. Finally, the antibacterial mechanism of chitosan fiber was obtained. The results show that the inhibition rate of samples I, K, L, and M against Staphylococcus aureus first increased and then decreased with the increase of Mw, and their bactericidal activity against Escherichia coli decreased with the increase of Mw when the DD was similar. This study provides an effective strategy for characterizing the chitosan fiber and the resultant relationship between antibacterial property and structural parameters that may benefit the enhancement of antibacterial activity and application in antibacterial textiles.

Preparation of Needleless Electrospinning Polyvinyl Alcohol/Water-Soluble Chitosan Nanofibrous Membranes: Antibacterial Property and Filter Efficiency

Electrospinning is an efficient method of producing nanofibers out of polymers that shows a great potential for the filtration territory. Featuring water-soluble chitosan (WS-CS), a low-pollution process and a self-made needleless machine, PVA/WS-CS nanofibrous membranes were prepared and evaluated for nanofiber diameter, bacteriostatic property, filtration efficiency, pressure drop, and quality factor. Test results indicate that the minimal fiber diameter was 216.58 ± 58.15 nm. Regardless of the WS-CS concentration, all of the PVA/WS-CS nanofibrous membranes attained a high porosity and a high water vapor transmission rate (WVTR), with a pore size of 12.06–22.48 nm. Moreover, the membranes also exhibit bacteriostatic efficacy against Staphylococcus aureus, an optimal quality factor of 0.0825 Pa⁻¹, and a filtration efficiency as high as 97.0%, that is 72.5% higher than that of common masks.

Rational Design and Preparation of Functional Hydrogels for Skin Wound Healing

Skin wound healing often contains a series of dynamic and complex physiological healing processes. It is a great clinical challenge to effectively treat the cutaneous wound and regenerate the damaged skin. Hydrogels have shown great promise for skin wound healing through the rational design and preparation to endow with specific functionalities. In the mini review, we firstly introduce the design and construction of various types of hydrogels based on their bonding chemistry during cross-linking. Then, we summarize the recent research progress on the functionalization of bioactive hydrogel dressings for skin wound healing, including anti-bacteria, anti-inflammatory, tissue proliferation and remodeling. In addition, we highlight the design strategies of responsive hydrogels to external physical stimuli. Ultimately, we provide perspectives on future directions and challenges of functional hydrogels for skin wound healing.

A review of the antiviral activity of Chitosan, including patented applications and its potential use against COVID-19

Chitosan is an abundant organic polysaccharide, which can be relatively easily obtained by chemical modification of animal or fungal source materials. Chitosan and its derivatives have been shown to exhibit direct antiviral activity, to be useful vaccine adjuvants and to have potential anti-SARS-CoV-2 activity. This thorough and timely review looks at the recent history of investigations into the role of chitosan and its derivatives as an antiviral agent and proposes a future application in the treatment of endemic SARS-CoV-2.

Application of Electrospinning in Antibacterial Field

In recent years, electrospun nanofibers have attracted extensive attention due to their large specific surface area, high porosity, and controllable shape. Among the many applications of electrospinning, electrospun nanofibers used in fields such as tissue engineering, food packaging, and air purification often require some antibacterial properties. This paper expounds the development potential of electrospinning in the antibacterial field from four aspects: fiber morphology, antibacterial materials, antibacterial mechanism, and application fields. The effects of fiber morphology and antibacterial materials on the antibacterial activity and characteristics are first presented, then followed by a discussion of the antibacterial mechanisms and influencing factors of these materials. Typical application examples of antibacterial nanofibers are presented, which show the good prospects of electrospinning in the antibacterial field.

DBU Catalyzed Phospho-Aldol-Brook Rearrangement for Rapid Preparation of α-Phosphates Amide in Solvent-Free Conditions

The 1,8-diazabicyclo [5.4.0] undec-7-ene DBU-catalyzed Phospho-Aldol-Brook Rearrangement reaction of α-ketoamide and dialkyl phosphites was developed under solvent-free at room temperature. The novel α-Phosphate Amide derivatives could be obtained with good yield (86–96%), which also exhibited good tolerance of various dialkyl phosphites and α-ketoamide, including isatins. In addition, the reaction was conducted in both gram-scale and mol-scale, and the title compounds could also be obtained in excellent yield (more than 91%) within 5 min.