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18 pages, 10969 KiB

Open AccessEditor’s ChoiceArticle

Porous Chitosan/Hydroxyapatite Composite Microspheres for Vancomycin Loading and Releasing

by Meng-Ying Wu, Yi-Ting Kuo, I-Fang Kao and Shiow-Kang Yen

Pharmaceutics 2024, 16(6), 730; https://doi.org/10.3390/pharmaceutics16060730 - 29 May 2024

Cited by 4 | Viewed by 1759

Porous chitosan/hydroxyapatite (Chi-HAp) composite microspheres were prepared in an aqueous solution containing chitosan, calcium nitrate, and ammonium dihydrogen phosphate by using a hydrothermal method at various temperatures. The investigation indicated that temperature significantly impacted the final product’s appearance. Hydroxyapatite (HAp) coupled with dicalcium phosphate dihydrate (DCPD) flakes were obviously found at 65 and 70 °C, while the latter gradually disappeared at higher temperatures. Conversely, synthesis at 90 °C led to smaller particle sizes due to the broken chitosan chains. The microspheres synthesized at 75 °C were selected for further analysis, revealing porous structures with specific surface areas of 36.66 m²/g, pores ranging from 3 to 100 nm, and pore volumes of 0.58 cm³/g. Vancomycin (VCM), an antibiotic, was then absorbed on and released from the microspheres derived at 75 °C, with a drug entrapment efficiency of 20% and a release duration exceeding 20 days. The bacteriostatic activity of the VCM/composite microspheres against Staphylococcus aureus increased with the VCM concentration and immersion time, revealing a stable inhibition zone diameter of approximately 4.3 mm from 24 to 96 h, and this indicated the retained stability and efficacy of the VCM during the encapsulating process. Full article

(This article belongs to the Special Issue Design of Mesoporous Materials for Biomedical Application)

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19 pages, 13906 KiB

Open AccessArticle

The Preparation and Characterization of Chitosan/Calcium Phosphate Composite Microspheres for Biomedical Applications

by Meng-Ying Wu, Shih-Wei Huang, I-Fang Kao and Shiow-Kang Yen

Polymers 2024, 16(2), 167; https://doi.org/10.3390/polym16020167 - 5 Jan 2024

Cited by 16 | Viewed by 3150

Abstract

In this study, we successfully prepared porous composite microspheres composed of hydroxyapatite (HAp), di-calcium phosphate di-hydrated (DCPD), and chitosan through the hydrothermal method. The chitosan played a crucial role as a chelating agent to facilitate the growth of related calcium phosphates. The synthesized porous composite microspheres exhibit a specific surface area of 38.16 m²/g and a pore volume of 0.24 cm³/g, with the pore size ranging from 4 to 100 nm. Given the unique properties of chitosan and the exceptional porosity of these composite microspheres, they may serve as carriers for pharmaceuticals. After being annealed, the chitosan transforms into a condensed form and the DCPD transforms into Ca₂P₂O₇ at 300 °C. Then, the Ca₂P₂O₇ initially combines with HAp to transform into β tricalcium phosphate (β-TCP) at 500 °C where the chitosan is also completely combusted. Finally, the microspheres are composed of Ca₂P₂O₇, β-TCP, and HAp, also making them suitable for applications such as injectable bone graft materials. Full article

(This article belongs to the Special Issue Preparation and Application of Biomass-Based Materials)

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14 pages, 5890 KiB

Open AccessArticle

Effects of Chitosan on Loading and Releasing for Doxorubicin Loaded Porous Hydroxyapatite–Gelatin Composite Microspheres

by Meng-Ying Wu, Yu-Hsin Liang and Shiow-Kang Yen

Polymers 2022, 14(20), 4276; https://doi.org/10.3390/polym14204276 - 12 Oct 2022

Cited by 13 | Viewed by 3053

Abstract

Porous hydroxyapatite–gelatin (Hap–Gel) composite microspheres derived by wet chemical methods were used as carriers of doxorubicin (DOX) coupled with chitosan (Chi) for treating cancers. Through X-ray diffraction, specific surface area porosimetry, chemisorption analysis and inductively coupled plasma mass spectrometry, the crystalline phase, composition, morphology, and pore distribution of HAp–Gel microspheres were all characterized. HAp nanosized crystals and Gel polymers form porous microspheres after blending and exhibit a specific surface area of 158.64 m²/g, pore sizes from 3 to 150 nm, and pore volumes of 0.4915 cm³/g. These characteristics are suitable for carriers of DOX. Furthermore, by the addition of chitosan during drug loading, its drug-entrapment efficiency increases from 70% to 99% and the release duration increases from a 100% burst within a day to only 45% over half a year since the pores in the composite microspheres provide a shielding effect throughout the degradation period of the chitosan. According to the MTT tests, cell viability of DOX–Chi/HAp–Gel is 57.64% on day 5, similar to the result treated with DOX only. It is concluded that under the protection of pores in the microspheres, the chitosan abundant of hydroxyls combining HAp–Gel and DOX by forming hydrogen bonds indeed enhances the entrapment efficiency, prolongs the releasing period and maintains DOX’s ability to perform medicine functions unaffected after loading. Full article

(This article belongs to the Special Issue Advance in Preparation and Application of Chitosan, Chitin and Their Composites II)

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20 pages, 610 KiB

Open AccessReview

Chitosan-Based Biomimetically Mineralized Composite Materials in Human Hard Tissue Repair

by Die Hu, Qian Ren, Zhongcheng Li and Linglin Zhang

Molecules 2020, 25(20), 4785; https://doi.org/10.3390/molecules25204785 - 19 Oct 2020

Cited by 53 | Viewed by 6434

Abstract

Chitosan is a natural, biodegradable cationic polysaccharide, which has a similar chemical structure and similar biological behaviors to the components of the extracellular matrix in the biomineralization process of teeth or bone. Its excellent biocompatibility, biodegradability, and polyelectrolyte action make it a suitable organic template, which, combined with biomimetic mineralization technology, can be used to develop organic-inorganic composite materials for hard tissue repair. In recent years, various chitosan-based biomimetic organic-inorganic composite materials have been applied in the field of bone tissue engineering and enamel or dentin biomimetic repair in different forms (hydrogels, fibers, porous scaffolds, microspheres, etc.), and the inorganic components of the composites are usually biogenic minerals, such as hydroxyapatite, other calcium phosphate phases, or silica. These composites have good mechanical properties, biocompatibility, bioactivity, osteogenic potential, and other biological properties and are thus considered as promising novel materials for repairing the defects of hard tissue. This review is mainly focused on the properties and preparations of biomimetically mineralized composite materials using chitosan as an organic template, and the current application of various chitosan-based biomimetically mineralized composite materials in bone tissue engineering and dental hard tissue repair is summarized. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Derivatives and Applications)

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