Biodegradable chitosan-based composites with dual functions acting as the bone scaffold and the inflammation inhibitor in the treatment of bone defects

Manufacturing methods, properties, and potential applications in bone tissue regeneration of hydroxyapatite-chitosan biocomposites: A review

Hydroxyapatite (HA) and chitosan (CS) biopolymer are the major materials investigated for biomedical purposes. Both of these components play an important role in the orthopedic field as bone substitutes or drug release systems. Used separately, the hydroxyapatite is quite fragile, while CS mechanical strength is very weak. Therefore, a combination of HA and CS polymer is used, which provides excellent mechanical performance with high biocompatibility and biomimetic capacity. Moreover, the porous structure and reactivity of the hydroxyapatite-chitosan (HA-CS) composite allow their application not only as a bone repair but also as a drug delivery system providing controlled drug release directly to the bone site. These features make biomimetic HA-CS composite a subject of interest for many researchers. Through this review, we provide the important recent achievements in the development of HA-CS composites, focusing on manufacturing techniques, conventional and novel three-dimensional bioprinting technology, and physicochemical and biological properties. The drug delivery properties and the most relevant biomedical applications of the HA-CS composite scaffolds are also presented. Finally, alternative approaches are proposed to develop HA composites with the aim to improve their physicochemical, mechanical, and biological properties.

A CS-based composite scaffold with excellent photothermal effect and its application in full-thickness skin wound healing

The development of natural polymer-based scaffolds with excellent biocompatibility, antibacterial activity, and blood compatibility, able to facilitate full-thickness skin wound healing, remains challenging. In this study, we have developed three chitosan (CS)-based porous scaffolds, including CS, CS/CNT (carbon nanotubes) and CS/CNT/HA (nano-hydroxyapatite, n-HA) using a freeze-drying method. All three scaffolds have a high swelling ratio, excellent antibacterial activity, outstanding cytocompatibility and blood compatibility in vitro. The introduction of CNTs exhibited an obvious increase in mechanical properties and exerts excellent photothermal response, which displays excellent healing performance as a wound dressing in mouse full-thickness skin wound model when compared to CS scaffolds. CS/CNT/HA composite scaffolds present the strongest ability to promote full-thickness cutaneous wound closure and skin regeneration, which might be ascribed to the synergistic effect of photothermal response from CNT and excellent bioactivity from n-HA. Overall, the present study indicated that CNT and n-HA can be engineered as effective constituents in wound dressings to facilitate full-thickness skin regeneration.

Dual-functional composite scaffolds for inhibiting infection and promoting bone regeneration

The treatment of infected bone defects is an intractable problem in orthopedics. It comprises two critical parts, namely that of infection control and bone defect repair. According to these two core tasks during treatment, the ideal approach of simultaneously controlling infection and repairing bone defects is promising treatment strategy. Several engineered biomaterials and drug delivery systems with dual functions of anti-bacterial action and ostogenesis-promotion have been developed and demonstrated excellent therapeutic effects. Compared with the conventional treatment method, the dual-functional composite scaffold can provide one-stage treatment avoiding multiple surgeries, thereby remarkably simplifying the treatment process and reducing the treatment time, overcoming the disadvantages of conventional bone transplantation. In this review, the impaired bone repair ability and its specific mechanisms in the microenvironment of pathogen infection and excessive inflammation were analyzed, providing a theoretical basis for the treatment of infectious bone defects. Furthermore, we discussed the composite dual-functional scaffold composed of a combination of antibacterial and osteogenic material. Finally, a series of advanced drug delivery systems with antibacterial and bone-promoting capabilities were summarized and discussed. This review provides a comprehensive understanding for the microenvironment of infectious bone defects and leading-edge design strategies for the antibacterial and bone-promoting dual-function scaffold, thus providing clinically significant treatment methods for infectious bone defects.

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Antibacterial and bone-promoting dual-function scaffolds are ideal strategies for treatment of infectious bone defects.

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The effect of infection on bone repair was summarized in detail from four important aspects.

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A variety of dual-function scaffolds based on antibacterial and osteogenic materials were discussed.

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Dual-function drug delivery systems promoting repair of infectious bone defects by locally releasing functional agents.

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Leading-edge design strategies, challenges and prospects for dual-functional biomaterials were provided.

Chitosan as Bone Scaffold for Craniofacial Bone Regeneration: A Systematic Review

Background: The reconstruction of bone defect in the face and head is indispensable yet one of the most challenging procedure to date. Chitosan has emerged as a promising low-cost natural biopolymer for the bone scaffold as an alternative to surgery. This study aims to review the effectiveness of chitosan as a bone scaffold for craniofacial bone regeneration. Methods: This systematic review used Google Scholar and PubMed as database sources. Study selection using PRISMA diagram and Boolean operator to specify the study search. The quality assessment of the study used a checklist from Joanna Briggs Institute for experimental study. Result: We included 18 experimental studies, both in vivo and in vitro study—the in vivo study used animal subjects such as mice, goats and rabbits. The studies mostly used chitosan combined with other biomaterials such as demineralized bone matrix (DBM), genipin (GP), sodium alginate (SA), resveratrol (Res), polycaprolactone (PCL) and collagen, growth factor and stem cells such as bone morphogenic protein-2 (BMP-2), dental pulp stem cell (DPSC), and human umbilical cord mesenchymal stem cells (hUCMSC). Conclusion: Chitosan is a natural polymer with promising osteoconductive, osteoinductive and osteo-integrative effects in bone regeneration. Chitosan utilization for bone scaffolds combined with other biomaterials, growth factors, or stem cells gives better bone regeneration results than chitosan alone.

Formulation and characterization of hydroxyapatite-based composite with enhanced compressive strength and controlled antibiotic release

A composite based on hydroxyapatite (HA) and chitosan (CS) combined with ciprofloxacin (CIP) was formulated by the solid-liquid mixing method. The optimization of the solid to the liquid ratio and the use of chitosan in a small amount (≤5 wt%) promoted the preparation of stable and rigid monoliths. A synergistic effect of CS and CIP contents on the compressive strength of the CIP-loaded composite was evidenced. The compressive strength of the fabricated biocomposite ranged in values from 1 to 6 MPa, comparable to those reported for cancellous bone. The improvement of the mechanical properties with the increase of the rate of organic components was correlated with the diminution of the surface area and the reduction in the pore volume of the specimens. On the other hand, the in vitro release experiments of the antibiotic indicated a sustained and controlled release of CIP over 10 days. Moreover, in vitro antibacterial tests performed on the biocomposite HA-CS5-CIP showed significant inhibition of Staphylococcus aureus and Escherichia coli pathogens. According to the showed results, the formulated composite with three-phase components could be a promising material for bone repair and local antibiotic release for the treatment of bone infections.