Preparation and Properties of Bimetallic Chitosan Spherical Microgels

Functional potential of chitosan-metal nanostructures: Recent developments and applications

Chitosan (Cs), a naturally occurring biopolymer, has garnered significant interest due to its inherent biocompatibility, biodegradability, and minimal toxicity. This study investigates the effectiveness of various reaction strategies, including acylation, acetylation, and carboxymethylation, to enhance the solubility profile of Cs. This review provides a detailed examination of the rapidly developing field of Cs-based metal complexes and nanoparticles. It delves into the diverse synthesis methodologies employed for their fabrication, specifically focusing on ionic gelation and in-situ reduction techniques. Furthermore, the review offers a comprehensive analysis of the characterization techniques utilized to elucidate the physicochemical properties of these complexes. A range of analytical techniques are utilized, including Ultraviolet-Visible Spectroscopy (UV-Vis), Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and others. By comprehensively exploring a wide range of applications, the review emphasizes the significant potential of Cs in various scientific disciplines. Diagrams, figures, and tables effectively illustrate the synthesis processes, promoting a clear understanding for the reader. Chitosan-metal nanostructures/nanocomposites significantly enhance antimicrobial efficacy, drug delivery, and environmental remediation compared to standard chitosan composites. The integration of metal nanoparticles, such as silver or gold, improves chitosan's effectiveness against a range of pathogens, including resistant bacteria. These nanocomposites facilitate targeted drug delivery and controlled release, boosting therapeutic bioavailability. Additionally, they enhance chitosan's ability to absorb heavy metals and dyes from wastewater, making them effective for environmental applications. Overall, chitosan-metal nanocomposites leverage chitosan's biocompatibility while offering improved functionalities, making them promising materials for diverse applications. This paper sheds light on recent advancements in the applications of Cs metal complexes for various purposes, including cancer treatment, drug delivery enhancement, and the prevention of bacterial and fungal infections.

Chitosan-copper microparticles as doxorubicin microcarriers for bone tumor therapy

Doxorubicin (DOX) is a chemotherapeutic drug used in osteosarcoma treatments, usually administrated in very high dosages. This study proposes novel DOX microcarriers based on chitosan (CHT) physically crosslinked with copper(II) ions that will act synergically to inhibit tumor growth at lower drug dosage without affecting the healthy cells. Spherical CHT-Cu microparticles with a smooth surface and an average size of 30.1 ± 9.1 µm were obtained by emulsion. The release of Cu2+ ions from the CHT-Cu microparticles showed that 99.4 % of added cupric ions were released in 72 h of incubation in a complete cell culture medium (CCM). DOX entrapment in microparticles was conducted in a phosphate buffer solution (pH 6), utilizing the pH sensitivity of the polymer. The successful drug-loading process was confirmed by DOX emitting red fluorescence from drug-loaded microcarriers (DOX@CHT-Cu). The drug release in CCM showed an initial burst release, followed by sustained release. Biological assays indicated mild toxicity of CHT-Cu microparticles on the MG-63 osteosarcoma cell line, without affecting the viability of human mesenchymal stem cells (hMSCs). The DOX@CHT-Cu microparticles at concentration of 0.5 mg mL‒1 showed selective toxicity toward MG-63 cells.

Recent developments in chitosan based microgels and their hybrids

Chitosan based microgels have gained great attention because of their chemical stability, biocompatibility, easy functionalization and potential uses in numerous fields. Production, properties, characterization and applications of chitosan based microgels have been systematically reviewed in this article. Some of these systems exhibit responsive behavior towards external stimuli like pH, light, temperature, glucose, etc. in terms of swelling/deswelling in an aqueous medium depending upon the functionalities present in the network which makes them a potential candidate for various applications in the fields of biomedicine, agriculture, catalysis, sensing and nanotechnology. Current research development and critical overview in this field accompanying by future possibilities is presented. The discussion is concluded with recommended possible future works for further progress in this field.

Copper-zinc/chitosan complex hydrogels: Rheological, degradation and biological properties

Polymer hydrogels crosslinked by therapeutic metal ions have attracted increased interest in recent years due to their unique and versatile properties. Chitosan hydrogels are widely investigated for various biomedical applications such as tissue engineering and drug delivery. Copper and zinc ions are considered as therapeutic metal ions, that have important roles in bone regeneration. The aim of this study was to investigate the physicochemical and biological properties of bimetallic-chitosan complex hydrogels with different cupric and zinc ions content. Scanning electron microscopy (SEM) revealed changes in the morphology from the microstructure with larger, tubular pores for aerogels with higher Zn content, to the sheets-like structure with long pores for samples with higher Cu content. FTIR analysis indicated the formation of bimetallic-chitosan aerogels. The obtained X-ray diffraction patterns showed a broadening of chitosan's characteristic diffraction maximum, while characterization of physical properties showed decreased swelling ability and increased shear modulus with higher Cu content. ICP-MS results showed a negligible amount of copper and zinc ions released under physiological conditions during 24 h indicating a strong physical crosslink between metal ions and chitosan chains. Furthermore, accelerated in vitro degradation showed that hydrogels maintained good stability during four weeks of lysozyme activity. The MTT assay indicated that the cytotoxicity of Cu2+-Zn2+/chitosan complexes could be adjusted by the amount of cupric ions. All results imply that Cu2+ and Zn2+ ions act as physical crosslinkers of the polymer network. Also, results are in agreement with the prediction of density functional theory (DFT) which indicated stronger chitosan-Cu tetrahedral aqua complex interactions in comparison to the chitosan-[Zn(H2O)4]2+ interactions.