Synthesis and Unusual Swelling Behavior of Combined Cationic/Non‐Ionic Hydrogels Based on Chitosan

Abstract

Hydrogel‐forming copolymers based on chitosan grafted with different amounts of polyacrylamide were synthesized and its swelling capacity determined in distilled water, sodium chloride solutions, as well as in buffer solutions at pH 1.2 and 8.0. The resulting products are highly efficient as hydrogel‐forming materials with swelling at equilibrium going approximately from 300 to 3 000 times the volume of the dry solid polymer in all the investigated media. The products, different to usual hydrogels, swells considerably more and quickly in electrolyte‐containing solutions compared to in distilled water. This has been attributed to their structure that contains non‐ionic polyacrylamide macromolecules grafted onto the trunk polymer chitosan, which is cationic in nature. In‐vitro drug‐release behavior of formulations containing grafted copolymers have been tested using theophylline as a water‐soluble drug and the results were compared with similar formulations containing unmodified chitosan. It was found that tablets based on formulations containing grafted chitosan show higher erosion and swelling compared with those of the matrix based on unmodified chitosan, leading to a higher fraction of theophylline released. It can be concluded that formulations based on the synthesized copolymers are potentially useful for fluid absorbency and as prolonged drug‐release matrices.The swelling of one of the hydrogels studied here.magnified imageThe swelling of one of the hydrogels studied here.

Molecular Dynamics of a Water-Absorbent Nanoscale Material Based on Chitosan

“…Hydrogels are materials capable of absorbing water within networks of entangled hydrophilic polymers . They are promising given their low manufacturing cost and numerous applications in science and industry. , Research in this field has expanded during the past 30 years, integrating scientists from several disciplines. , …”

“…Chitosan enhances the transport of polar drugs across epithelial surfaces, and it is biocompatible and biodegradable. ,− Given their special characteristics, chitosan hydrogels have already been used in several applications: thickening agents for foods, moisture releasers to plants, hydrophilic coatings for textiles, separation and diffusion gels in chromatography and electrophoresis, − contact lenses, and as drug-delivery matrices. ,− Even though hydrogels have been widely investigated, there is a limited amount of modeling studies that discuss in detail their water-absorbent features. ,− …”

“…3,4 Research in this field has expanded during the past 30 years, integrating scientists from several disciplines. 5,6 Recently hydrogels have been used in health care and pharmaceuticals due to their unique and attractive hydrophilic, mechanical, and biocompatibility properties, which make them excellent candidates for controlled-release 7−9 and targeted drug-delivery systems. 10−13 The use of hydrogels, such as chitosan, as matrices for drugs has been employed in a considerable number of approved pharmaceutical products during the past 15 years.…”

Comparative effect of human andTrypanosoma cruzicalreticulin in wound healing

“…The use of chitosan‐based scaffold biomaterials for different tissue engineering applications is well known (Fernandez et al ., ; Kim et al ., ). Because of the chitosan swelling behaviour and other biocompatible properties (Yazdani‐Pedram et al ., ), its use as an implant embedded with human or parasite CRTs was explored. Chitosan acts as a slow drug‐delivery device, thus increasing the CRT wound‐healing efficiency, allowing the use of lower doses and no treatment repetitions.…”

Evaluation of a multilayered chitosan-hydroxy-apatite porous composite enriched with fibronectin or an in vitro-generated bone-like extracellular matrix on proliferation and diferentiation of osteoblasts

“…However, freeze‐drying and freeze‐gelation methods produce membranes or few‐layered homogeneous scaffolds. Finally, one of the main problems of chitosan‐based scaffolds is the chitosan wettability and swelling behaviour, which can produce a volume increase of up to 300% (Yazdani‐Pedram et al , 2003).…”