Antimicrobial Application of Chitosan Derivatives and their Nanocomposites.

Chitosan is derived from chitin polysaccharide, the main component of crustacean shells. Chitosan is a biocompatible, nontoxic, and biodegradable polymer soluble in acidic solutions. It is widely used in the medical and pharmaceutical fields. Antimicrobial activities of chitosan against different bacterial, fungal, and viral pathogens have been considered one of its attractive properties, making chitosan valuable for biological applications, including textile, food, tissue engineering, agriculture, and environmental protection. Additionally, chitosan has beneficial effects on livestock, poultry, fish, and crustaceans, which can enhance immunity, improve feed conversion, and promote growth. However, the water solubility of chitosan influences antimicrobial capabilities, limiting its application. In the present work, we reviewed the preparation, factors affecting antimicrobial activity, morphological structure, antimicrobial mechanism, and application of chitosan derivatives, and the problems and prospects were pointed out. Collectively, this review provided an update on the application of chitosan derivatives and their potential for further advanced applications in the antimicrobial field.

Chitosan-Based Nanomaterial as Immune Adjuvant and Delivery Carrier for Vaccines.

With the support of modern biotechnology, vaccine technology continues to iterate. The safety and efficacy of vaccines are some of the most important areas of development in the field. As a natural substance, chitosan is widely used in numerous fields-such as immune stimulation, drug delivery, wound healing, and antibacterial procedures-due to its good biocompatibility, low toxicity, biodegradability, and adhesion. Chitosan-based nanoparticles (NPs) have attracted extensive attention with respect to vaccine adjuvants and delivery systems due to their excellent properties, which can effectively enhance immune responses. Here, we list the classifications and mechanisms of action of vaccine adjuvants. At the same time, the preparation methods of chitosan, its NPs, and their mechanism of action in the delivery system are introduced. The extensive applications of chitosan and its NPs in protein vaccines and nucleic acid vaccines are also introduced. This paper reviewed the latest research progress of chitosan-based NPs in vaccine adjuvant and drug delivery systems.

Curcumin encapsulation in self-assembled nanoparticles based on amphiphilic palmitic acid-grafted-quaternized chitosan with enhanced cytotoxic, antimicrobial and antioxidant properties.

The practical application of curcumin (CUR) is greatly limited due to its instability, high hydrophobicity, low bioavailability, and inability to cross the mucosal barrier of gastrointestinal tract. To overcome these disadvantages, several delivery systems have been explored to formulate CUR for oral administration. Nanoparticles (NPs) can significantly enhance oral absorption, bioavailability and therapeutic efficacy of drug, however, NPs are limited by the gastrointestinal degradation, mucosal and epithelial barriers. A novel amphiphilic quaternary ammonium chitosan (N-2-HACC) based NP delivery carrier was prepared using palmitic acid (PA) to encapsulate CUR. Palmitoyl chitosan (PA-N-2-HACC) was characterized including FT-IR, 1H NMR, TGA, and CAC. The particle size of PA-N-2-HACC NPs and PA-N-2-HACC NPs loaded with CUR (CUR@PA-N-2-HACC NPs) was 231.6 ± 9.24 nm and 264.5 ± 4.31 nm. The encapsulation efficiency and loading capacity of CUR@PA-N-2-HACC NPs was 75.43 ± 1.25 % and 6.81 ± 0.16 %. CUR@PA-N-2-HACC NPs exhibited sustained and controlled release. Compared with the CUR, minimum inhibitory concentration of the CUR@PA-N-2-HACC NPs against Escherichia coli, Staphylococcus aureus and Candida albicans was reduced by 4.2 times, 1.6 times and 4.6 times, respectively. Moreover, the antioxidant activity of CUR@PA-N-2-HACC NPs was dose-dependent and higher than that of free CUR. The PA-N-2-HACC NPs show little toxicity and are a promising delivery system for encapsulating hydrophobic drugs.

Immune enhancement of N-2-Hydroxypropyl trimethyl ammonium chloride chitosan/carboxymethyl chitosan nanoparticles vaccine.

The immunogenicity and toxicity of N-2-Hydroxypropyl trimethyl ammonium chloride chitosan/N, O-carboxymethyl chitosan nanoparticles (N-2-HACC/CMCS NPs) as a universal vaccine adjuvant/delivery system remains unclear. The present study indicated that the positively charged N-2-HACC/CMCS NPs showed a regular spherical morphology, with a particle size of 219 ± 13.72 nm, zeta potential of 37.28 ± 4.58 mV, had hemocompatibility and biodegradation. Acute toxicity, repeated dose toxicity, abnormal toxicity, muscle stimulation, whole body allergic reaction evaluation in vitro, and cytotoxicity in vivo confirmed N-2-HACC/CMCS NPs is safe and non-toxic. N-2-HACC/OVA/CMCS NPs were prepared to evaluate the immunogenicity, which showed a particle size of 248.1 ± 15.53 nm, zeta potential of 17.24 ± 1.28 mV, encapsulation efficiency of 92.43 ± 0.96 %, and loading capacity of 42.97 ± 0.07 %. Oral or intramuscular route with the N-2-HACC/OVA/CMCS NPs in mice not only induced higher IgG, IgG1, IgG2a, and sIgA antibody titers, but also significantly produced higher levels of IL-6, IL-4, IFN-γ, and TNF-α, demonstrating that the N-2-HACC/OVA/CMCS NPs enhance humoral, cellular, and mucosal immune responses. Our results not only support the N-2-HACC/CMCS NPs to be a safe and potential universal nano adjuvant/delivery system in vaccine development, especially mucosal vaccines, but also rich the database knowledge of adjuvant/delivery systems, and provide new direction to introduce more licensed adjuvants.