The phenomenon of releasing large amounts of drug in a short period of time is called "drug burst release". Drug burst release results in a high initial drug concentration, which is harmful to normal human cells and shortens the effective life of the drug delivery system. Therefore, it is very important to control the drug release behaviour. The main purpose of controlled drug release is to provide a relatively stable drug release rate, prolong the drug action time, reduce the number of drug administrations and reduce the toxicity caused by drug burst release so as to optimise the effect of drug therapy. Commonly used controlled release drug carriers are generally divided into two categories: biodegradable polymers and non-biodegradable polymers. Among them, non-biodegradable polymers do not degrade in the body and are prone to inflammatory reactions. Therefore, biodegradable polymers have become the first choice for controlled-release drug carriers. Chitosan is a deacetylated product of chitin with the molecular formula (C6H11NO4)n. It is the second most abundant bio-derived polysaccharide in the world. It has the characteristics of wide source, low cost, no pollution, degradable, good biocompatibility, antibacterial, haemostasis, etc. It is widely used in biomedical fields such as wound repair and controlled release drug carriers. Chitosan can be processed into various forms such as films, microspheres, hydrogels, aerogels, nanofibres, etc. Among them, aerogel, as a lightweight porous material with three-dimensional network structure, has the characteristics of low density, high porosity and large specific surface area. It has a good controlled drug release effect while achieving high drug loading, and can respond intelligently to changes in the pH of the environment. It is an excellent excipient.
Figure 1. Influence of Cu2+ on CS hydrogel structure. (Nie J, et al. 2016)
The drug-controlled release system refers to a drug delivery system formed by combining drugs or other active factors with various polymer drug carriers. It can achieve directional and stable release of drugs in specific targeted tissues or organs, and give full play to the efficacy of drugs. Compared with conventional release, drug-controlled release has incomparable advantages: stable drug release mass concentration and efficient drug use; targeted drug release; reduced drug administration frequency; improved drug utilization and reduced toxic side effects of high-mass concentration drugs. An ideal drug-controlled release system requires that the material can accurately match the specific site to achieve directional and stable release, while minimizing the loss of drugs in the blood and maintaining the biological activity of the drug. Chitosan, as a natural polysaccharide, has good biodegradability and biocompatibility, and is a pH-sensitive polysaccharide, which enables chitosan-based aerogels to determine the lesion site through changes in pH in the environment and achieve targeted drug release. pH value is a widely used external stimulus. When the pH value is low, most of the amino groups in the chitosan-based aerogel drug delivery system are protonated, the electrostatic repulsion between ions increases significantly, the hydrogen bonding between amino groups weakens or even disappears, the biodegradability of chitosan increases in an acidic environment, the aerogel structure gradually collapses, and the drug molecules are released in a controlled manner. The chitosan-based composite aerogel compounded with multiple components has better mechanical properties, can delay the degradation of the drug delivery system structure, maintain the biological activity of the drug, avoid sudden drug release, and prolong the drug release time.
Due to human's bad health habits and the gradual aging of the population, the incidence of chronic wounds such as diabetic foot ulcers and venous leg ulcers has gradually increased. The healing of such chronic wounds is a difficult task in clinical practice. Hypoxia and bacterial infection are factors that hinder wound healing. Compared with traditional dressings such as gauze and sponges, chitosan-based aerogel drug delivery system can prevent wound infection while treating the wound locally. This is because the high porosity network structure of chitosan-based aerogel is conducive to the efficient absorption of wound exudate, and its excellent hemostatic, breathable and antibacterial properties are conducive to reducing bacterial infection in the wound after debridement and reducing inflammation. It can be seen that the chitosan-based aerogel drug delivery system with antibacterial properties has a broader development prospect than traditional dressings. In addition, the chitosan-based aerogel drug delivery system can also be used in areas with large pH differences in the gastrointestinal tract and digestive tract, as well as organs or tissues where the pH value changes after lesions. It is reported that more than 90% of cancer deaths are caused by the spread of tumor cells. The traditional cancer treatment method is to use drugs such as paclitaxel and doxorubicin through intravenous injection or oral administration, but these drugs usually have strong cytotoxicity, which will harm normal cells during the treatment process, and are easy to combine with proteins in the body during drug delivery, causing the loss of drug molecules. Therefore, the preparation of a chitosan-based drug controlled release system that can target and kill tumor cells has far-reaching significance in cancer treatment.
Alternate Names:
Chitosan-Cyanine5.5
Chitosan-Cyanine 5.5 conjugate
References:
1. Nie J, et al. Chitosan Hydrogel Structure Modulated by Metal Ions. Sci Rep. 2016, 6:36005.
A pH-responsive amphiphilic chitosan-pyranine core-shell nanoparticle for controlled drug delivery, imaging and intracellular pH measurement
J Mater Chem B
Authors: Chou HS , Hsiao MH , Hung WY , Yen TY , Lin HY , Liu DM .
Abstract
A pH-responsive multifunctional core-shell nanoparticle, named CHC-PY nanoparticle, was successfully synthesized through electrostatic interaction of a thin shell of fluorescent pyranine dye (PY) with amphiphilic carboxymethylhexanoyl chitosan (CHC) nanoparticles. Upon encapsulating an anticancer drug, camptothecin (CPT), the CHC-PY nanoparticles exhibited an excellent drug loading efficiency (>95%). The resulting CPT-loaded CHC-PY nanoparticles also exhibited efficient cell internalization and good pH-responsive behavior. After being internalized (via efficient endocytosis pathway), the presence of fluorescent PY shell showed a pH-dependent emission characteristic which allowed the internalized CHC-PY nanoparticles acting as an indicator to distinguish the acidic microenvironment of cancerous cells, compared with normal cells. The pH-sensitive PY shell also acted as a modulator to control the CPT release wherein a higher release rate was detected at lower pH value, which is essentially a potential therapeutic niche for anticancer purposes. This new type of CHC-PY core-shell nanoparticle provides multiple functionality, where a synergistic performance of nanotherapeutics, imaging and even diagnosis at a cellular resolution can be achieved simultaneously.
Chitosan Nanoparticles as a Novel Drug Delivery System: A Review Article
Curr Drug Targets
Authors: Matalqah SM, Aiedeh K, Mhaidat NM, Alzoubi KH, Bustanji Y, Hamad I.
Abstract
Natural polymers, particularly polysaccharide, have been used as drug delivery systems for a variety of therapeutic agents such as peptides, proteins, vaccines, DNA, and drugs for parenteral and non-parenteral administration. Chitosan, the second most abundant naturally occurring polysaccharide after cellulose, is a biocompatible and biodegradable mucoadhesive polymer that is extensively used in the preparation of nanoparticles (NPs). Chitosan NPs loaded with drugs were found to be stable, permeable and bioactive. In this review, the importance of chitosan and its derivatives in drug delivery is illustrated, different methods of preparation of chitosan and chitosan derivatives NPs and their physio- chemical properties are addressed. Moreover, the desirable characteristics of successful NPs based drug delivery systems, as well as the pharmaceutical applications of these NPs are also clearly explored.
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