Preparation of chitosan-hydroxyapatite composite mono-fiber using coagulation method and their mechanical properties

Optimization by mixture design of chitosan/multi-phase calcium phosphate/BMP-2 biomimetic scaffolds for bone tissue engineering

The modulation of cell behavior during culture is one of the most important aspects of bone tissue engineering because of the necessity for a complex mechanical and biochemical environment. This study aimed to improve the physicochemical properties of chitosan/multi-phase calcium phosphate (MCaP) scaffolds using an optimized mixture design experiment and evaluate the effect of biofunctionalization of the obtained scaffolds with the bone morphogenetic protein BMP-2 on stem cell behavior. The present study evaluated the compressive strength, elastic modulus, porosity, pore diameter, and degradation in simulated body fluids and integrated these responses using desirability. The properties of the scaffolds with the best desirability (18.4% of MCaP) were: compressive strength of 23 kPa, elastic modulus of 430 kPa, pore diameter of 163 μm, porosity of 92%, and degradation of 20% after 21 days. Proliferation and differentiation experiments were conducted using dental pulp stem cells after grafting BMP-2 onto scaffolds via the carbodiimide route. These experiments showed that MCaP promoted cell proliferation and increased alkaline phosphatase activity, whereas BMP-2 enhanced cell differentiation. This study demonstrates that optimizing the composition of a mixture of chitosan and MCaP improves the physicochemical and biological properties of scaffolds, indicating that this solution is viable for application in bone tissue engineering.

A Novel Chitosan Composite Biomaterial with Drug Eluting Capacity for Maxillary Bone Regeneration

Bone grafting is one of the most commonly performed treatments for bone healing or repair. Autografts, grafts from the same patient, are the most frequently used bone grafts because they can provide osteogenic cells and growth factors at the site of the implant with reduced risk of rejection or transfer of diseases. Nevertheless, this type of graft presents some drawbacks, such as pain, risk of infection, and limited availability. For this reason, synthetic bone grafts are among the main proposals in regenerative medicine. This branch of medicine is based on the development of new biomaterials with the goal of increasing bone healing capacity and, more specifically in dentistry, they aim at simultaneously preventing or eliminating bacterial infections. The use of fibers made of chitosan (CS) and hydroxyapatite (HA) loaded with an antibiotic (doxycycline, DX) and fabricated with the help of an injection pump is presented as a new strategy for improving maxillary bone regeneration. In vitro characterization of the DX controlled released from the fibers was quantified after mixing different amounts of HA (10-75%). The 1% CS concentration was stable, easy to manipulate and exhibited adequate cuttability and pH parameters. The hydroxyapatite concentration dictated the combined fast and controlled release profile of CSHA50DX. Our findings demonstrate that the CS-HA-DX complex may be a promising candidate graft material for enhancing bone tissue regeneration in dental clinical practice.

Current strategies for enhancement of the bioactivity of artificial ligaments: A mini-review

Background and objective

Anterior cruciate ligament (ACL) reconstruction calls for artificial ligaments with better bioactivity, however systematic reviews regarding bioactivity enhancement strategies, technologies, and perspectives of artificial ligaments have been rarely found.

Methods

Research papers, reviews, and clinical reports related to artificial ligaments were searched and summarized the current status and research trends of artificial ligaments through a systematic analysis.

Results

Having experienced ups and downs since the very first record of clinical application, artificial ligaments differing in material, and fabrication methods have been reported with different clinical performances. Various manufacturing technologies have developed and realized scaffold- and cell-based strategies. Despite encouraging in-vivo and in-vitro test results, the clinical results of such new designs need further clinical examinations.

Conclusion

As the demand for ACL reconstruction dramatically increases, novel artificial ligaments with better osteoinductivity and mechanical performance are promising.

The translational potential of this article

To develop novel artificial ligaments simultaneously possessing excellent osteoinductivity and satisfactory mechanical performance, it is important to grab a glance at recent research advances. This systematic analysis provides researchers and clinicians with comprehensive and comparable information on artificial ligaments, thus being of clinical translational significance.

Natural Drug-Loaded Bimetal-Substituted Hydroxyapatite-Polymeric Composite for Osteosarcoma-Affected Bone Repair

Repairing segmental bone deformities after resection of dangerous bone tumors is a long-standing clinical issue. The study's main objective is to synthesize a natural bioactive compound-loaded bimetal-substituted hydroxyapatite (BM-HA)-based composite for bone regeneration. The bimetal (copper and cadmium)-substituted HAs were prepared by the sol-gel method and reinforced with biocompatible polyacrylamide (BM-HA/PAA). Umbelliferone (UMB) drug was added to the BM-HA/PAA composite to enhance anticancer activity further. The composite's formation was confirmed by various physicochemical investigations, such as FT-IR, XRD, SEM, EDAX, and HR-TEM techniques. The bioactivity was assessed by immersing the sample in simulated body fluid for 1, 3, and 7 days. The zeta potential values of BM-HA/PAA and BM-HA/PAA/UMB are -36.4 mV and -49.4 mV, respectively. The in vitro viability of the prepared composites was examined in mesenchymal stem cells (MSCs). It shows the ability of the composite to produce osteogenic bone regeneration without any adverse effects. From the gene expression and PCR results, the final UMB-loaded composite induced osteogenic markers, such as Runx, OCN, and VEFG. The prepared bimetal substituted polyacrylamide reinforced HA composite loaded with UMB drug has the ability for bone repair/regenerations.

Hydroxyapatite Based Materials for Bone Tissue Engineering: A Brief and Comprehensive Introduction

Hydroxyapatite (HA) is widely used in bone tissue engineering for its bioactivity and biocompatibility, and a growing number of researchers are exploring ways to improve the physical properties and biological functions of hydroxyapatite. Up to now, HA has been used as inorganic building blocks for tissue engineering or as nanofillers to blend with polymers, furthermore, various methods such as ion doping or surface modification have been also reported to prepare functionalized HA. In this review, we try to give a brief and comprehensive introduction about HA-based materials, including ion-doped HA, HA/polymer composites and surface modified HA and their applications in bone tissue engineering. In addition, the prospective of HA is also discussed. This review may be helpful for researchers to get a general understanding about the development of hydroxyapatite based materials.

Silane Coupling Agent Modifies the Mechanical Properties of a Chitosan Microfiber

Chitosan microfibers are widely used in medical applications because they have favorable inherent properties. However, their mechanical properties require further improvement. In the present study, a trimethoxysilane aldehyde (TMSA) crosslinking agent was added to chitosan microfibers to improve their tensile strength. The chitosan microfibers were prepared using a coagulation method. The tensile strength of the chitosan microfibers was improved by crosslinking them with TMSA, even when only a small amount was used (less than 1%). TMSA did not change the orientation of the chitosan molecules. Furthermore, aldehyde derived from TMSA did not remain, and siloxane units were formed in the microfibers.

Tuning the physicochemical properties of apple pectin films by incorporating chitosan/pectin fiber

Various biodegradable or edible films were designed to deal with the environmental threats from plastic films. To overcome the defects of pectin film, the feasibility for the incorporation of CH/PE fiber was explored. Micron-scale novel artificial CH/PE fibers in needle, spindle or whisker shape with a diameter around 25 μm were fabricated via a shearing regime in virtue of electrostatic complexing. The incorporation of CH/PE fiber (mixture) and its size-fractioned portions (small and large) substantially changed PE films in diverse ways. Structurally, the fiber-incorporated films were heterogeneous with the fibers concentrated in the upper layer, although they presented similar FT-IR spectra and XRD pattern to PE film. Regarding the film performance, the incorporation of CH/PE fibers, especially the small portion, rendered the PE film with higher values in water-proof ability, thermal stability, break resistibility, stretchability and UV blocking capacity. More importantly, this work provided an innovative strategy to improve the performance of edible films.

Preparation and properties of a highly dispersed nano-hydroxyapatite colloid used as a reinforcing filler for chitosan

Hydroxyapatite/chitosan (HAp/CS) composites have been widely studied and applied in tissue engineering fields due to their excellent biocompatibility and degradability. However, to improve the mechanical properties of CS, cross-linking agents are commonly added, which will seriously affect its biocompatibility and safety. In this study, the homogenously dispersed nano-hydroxyapatite (nHAp) colloidal solution was first synthesized using a co-precipitation method. The three-dimensional porous nano-hydroxyapatite/chitosan (nHAp/CS) composite scaffolds with different nHAp contents were then obtained through an environmentally friendly freeze-drying process without any cross-linking. The microstructure, porosity, phase composition, swelling ratio, mechanical properties, and biocompatibility of the nHAp/CS scaffolds were thoroughly investigated. The as-prepared nHAp/CS scaffolds exhibited a high porosity and excellent swelling performance. Compared with pure CS scaffolds, the nHAp/CS composite scaffolds not only showed higher compressive modulus but also exhibited better biocompatibility. This study provides a simple and environmentally friendly technique to construct three-dimensional porous nHAp/CS composite scaffolds, which demonstrate promising potential by being a scaffold material for bone tissue engineering.

Development of hydroxyapatite from eggshell waste and a chitosan-based composite: In vitro behavior of human osteoblast-like cell (Saos-2) cultures

Hydroxyapatite was successfully synthesized using eggshell waste as a raw material. Eggshell waste and orthophosphoric acid were co-precipitated for 2 h at an ambient temperature. The pH of the solution was adjusted to 10 using ammonium hydroxide. Then, 10-30 wt% of hydroxyapatite was loaded into the chitosan film. Scanning electron microscopy and energy dispersive analyses confirmed the morphological properties and dispersion. A thermogravimetric analysis showed a significant enhancement in the thermal stability of the composite. The existence of hydroxyapatite resulted in a higher thermal stability. Furthermore, atomic force microscopy was used to investigate the roughness of the surface. With the addition of hydroxyapatite, the roughness significantly increased. The swelling behavior of the composite was observed in phosphate buffer saline solution. The hydroxyapatite offered the inferiority on the swelling behavior. A preliminary investigation on the in vitro behavior of Saos-2 was also performed. The composite presented good cytotoxicity, and thus, excellent properties as a tissue engineering material.