Regulating association strength between quaternary ammonium chitosan and sodium alginate via hydration

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.

"One-stop" synergistic strategy for hepatocellular carcinoma postoperative recurrence

Residual tumor recurrence after surgical resection of hepatocellular carcinoma (HCC) remains a considerable challenge that imperils the prognosis of patients. Notably, intraoperative bleeding and postoperative infection are potential risk factors for tumor recurrence. However, the biomaterial strategy for the above problems has rarely been reported. Herein, a series of cryogels (coded as SQ-n) based on sodium alginate (SA) and quaternized chitosan (QC) were synthesized and selected for optimal ratios. The in vitro assays showed that SQ-50 possessed superior hemostasis, excellent antibacterial property, and great cytocompatibility. Subsequently, SQAP was constructed by loading black phosphorus nanosheets (BPNSs) and anlotinib hydrochloride (AL3818) based on SQ-50. Physicochemical experiments confirmed that near-infrared (NIR)-assisted SQAP could control the release of AL3818 in photothermal response, significantly inhibiting the proliferation and survival of HUVECs and H22 cells. Furthermore, in vivo studies indicated that the NIR-assisted SQAP prevented local recurrence of ectopic HCC after surgical resection, achieved through the synergistic effect of mPTT and molecular targeted therapy. Thus, the multifunctional SQAP provides a "one-stop" synergistic strategy for HCC postoperative recurrence, showing great potential for clinical application.

Preparation and Properties of Self-Cross-Linking Hydrogels Based on Chitosan Derivatives and Oxidized Sodium Alginate

A self-cross-linking and biocompatible hydrogel has wide application potential in the field of tissue engineering. In this work, an easily available, biodegradable, and resilient hydrogel was prepared using a self-cross-linking method. This hydrogel was composed of N-2-hydroxypropyl trimethyl ammonium chloride chitosan (HACC) and oxidized sodium alginate (OSA). A stable and reversible cross-linking network was formed by the Schiff base self-cross-linked and hydrogen bonding. The addition of a shielding agent (NaCl) may weaken the intense electrostatic effect between HACC and OSA and solve the problem of flocculation caused by the rapid formation of ionic bonds, which provided an extended time for the Schiff base self-cross-linked reaction for forming a homogeneous hydrogel. Interestingly, the shortest time for the formation of the HACC/OSA hydrogel was within 74 s and the hydrogel had a uniform porous structure and enhanced mechanical properties. The HACC/OSA hydrogel withstood large compression deformation due to improved elasticity. What's more, this hydrogel possessed favorable swelling property, biodegradation, and water retention. The HACC/OSA hydrogels have great antibacterial properties against Staphylococcus aureus and Escherichia coli and demonstrated good cytocompatibility as well. The HACC/OSA hydrogels have a good sustained release effect on rhodamine (model drug). Thus, the obtained self-cross-linked HACC/OSA hydrogels in this study have potential applications in the field of biomedical carriers.

Complexation behavior of carboxymethyl short-chain amylose and quaternized chitosan

The complexation of carboxymethyl short-chain amylose (CSA) and hydroxypropyl trimethyl ammonium chloride chitosan (HACC) and the stability of CSA/HACC nanocomplex were investigated. Resonance light scattering (RLS), turbidity, nanoparticle size and zeta potential analyses revealed that the complex coacervation occurred between CSA and HACC. The mass ratio and pH markedly influenced the complexation behavior; CSA with a higher degree of substitution (DS0.2) altered the complexation at a lower mass ratio and pH, increasing the turbidity and RLS intensity. The results of particle size and zeta potential analyses indicated that CSA/HACC complexes possessed the good pH and ionic strength stability. In addition to electrostatic interactions, hydrogen bonding and hydrophobic effects were also determined to be involved in the complexation process using thermal titration calorimetry (ITC). Additionally, the process was spontaneous, and CSA with a higher DS showed stronger complexation ability. These results may enable the understanding of polysaccharide complex behaviors.

Facile formation of injectable quaternized chitosan/tannic acid hydrogels with antibacterial and ROS scavenging capabilities for diabetic wound healing

The wound healing process of the diabetic wound is often hindered by excessive oxygen free radicals and infection. An ideal wound dressing should possess great reactive oxygen species (ROS) scavenging property and considerable antibacterial ability. In this study, we facilely constructed a novel hydrogel dressing with excellent ROS scavenging property and outstanding antibacterial performance by introducing tannic acid (TA) into quaternized chitosan (QCS) matrix. Attributing to the suitable physical crosslinking between TA and QCS, this QCS/TA hydrogel was endowed with injectable and self-healing properties, which could avoid the various external squeezing on the irregular shape by wound dressing. The results showed that it could promote coagulation, suppress inflammation and expedite collagen deposition in the skin defect model of diabetic rats. This study provides a facile and convenient method for constructing injectable hydrogel dressing, which has application potentials in the clinical management of diabetic wounds.

Marine Polysaccharides as a Versatile Biomass for the Construction of Nano Drug Delivery Systems

Marine biomass is a treasure trove of materials. Marine polysaccharides have the characteristics of biocompatibility, biodegradability, non-toxicity, low cost, and abundance. An enormous variety of polysaccharides can be extracted from marine organisms such as algae, crustaceans, and microorganisms. The most studied marine polysaccharides include chitin, chitosan, alginates, hyaluronic acid, fucoidan, carrageenan, agarose, and Ulva. Marine polysaccharides have a wide range of applications in the field of biomedical materials, such as drug delivery, tissue engineering, wound dressings, and sensors. The drug delivery system (DDS) can comprehensively control the distribution of drugs in the organism in space, time, and dosage, thereby increasing the utilization efficiency of drugs, reducing costs, and reducing toxic side effects. The nano-drug delivery system (NDDS), due to its small size, can function at the subcellular level in vivo. The marine polysaccharide-based DDS combines the advantages of polysaccharide materials and nanotechnology, and is suitable as a carrier for different pharmaceutical preparations. This review summarizes the advantages and drawbacks of using marine polysaccharides to construct the NDDS and describes the preparation methods and modification strategies of marine polysaccharide-based nanocarriers.