Different natural and synthetic biodegradable polymers have been used in vaccine formulations
as adjuvant and delivery system but have faced various limitations. Chitosan is a new delivery
system with the potential to improve development of nano vaccines and drugs. However, chitosan
is only soluble in acidic solutions of low concentration inorganic acids such as dilute acetic acid
and dilute hydrochloric acid and in pure organic solvents, which greatly limits its application.
Chemical modification of chitosan is an important way to improve its weak solubility. Quaternized
chitosan not only retains the excellent properties of chitosan, but also improves its water solubility
for a wider application. Recently, quaternized chitosan nanoparticles have been widely used in biomedical
field. This review focuses on some quaternized chitosan nanoparticles, and points out the
advantages and research direction of quaternized chitosan nanoparticles. As shown by the applications
of quaternized chitosan nanoparticles as adjuvant and delivery carrier in vaccines, quaternized
chitosan nanoparticles have promising potential in application for the development of nano vaccines
in the future.
With the development of the times, it becomes difficult or even impossible for traditional wound dressings to meet people's needs for high-quality wound repair and management. Therefore, there is an urgent need for new biomedical dressings that can accelerate wound healing in clinical practice. In this study, N-2-hydroxypropyl trimethylammonium chloride chitosan (N-2-HACC), a derivative of chitosan, was used as raw material to sprepare N-2-HACC temperature sensitive hydrogel. The structure, thermal stability and water content of N-2-HACC temperature sensitive hydrogel were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. The safety of N-2-HACC temperature sensitive hydrogel was evaluated by in vitro cell assay and in vitro degradation assay, and the effect of N-2-HACC temperature sensitive hydrogel on wound healing was evaluated by wound healing experiment in SD rats. The results show that N-2-HACC hydrogel, as a wound dressing, has the characteristics of good biocompatibility, good biodegradation, non-toxic, antiinflammatory and so on. It plays a barrier role in the process of wound healing, provides a moist environment for the wound and accelerates wound healing. Therefore, N-2-HACC hydrogel has a broad application prospect in promoting wound healing as a wound dressing.
We study a double phase problem with mixed boundary value conditions with reaction terms that resonate at the first eigenvalue of the related eigenvalue problem. Based on the maximum principle and homological local linking, we are going to prove the existence of at least two bounded nontrivial solutions for this problem.
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