Radiation synthesis of gelatin/CM-chitosan/β-tricalcium phosphate composite scaffold for bone tissue engineering

O-carboxymethyl chitosan in biomedicine: A review

O-carboxymethyl chitosan (O-CMC) is a chitosan derivative produced through the substitution of hydroxyl (-OH) functional groups in glucosamine units with carboxymethyl (-CH2COOH) substituents, effectively addressing the inherent solubility issues of chitosan in aqueous solutions. O-CMC has garnered significant interest due to its enhanced solubility, elevated viscosity, minimal toxicity, and advantageous biocompatibility properties. Furthermore, O-CMC demonstrates antibacterial, antifungal, and antioxidant characteristics, rendering it a promising candidate for various biomedical uses such as wound healing, tissue engineering, anti-tumor therapies, biosensors, and bioimaging. Additionally, O-CMC is well-suited for the fabrication of nanoparticles, hydrogels, films, microcapsules, and tablets, offering opportunities for effective drug delivery systems. This review outlines the distinctive features of O-CMC, offers analyses of advancements and future potential based on current research, examines significant obstacles for clinical implementation, and foresees its ongoing significant impacts in the realm of biomedicine.

Fabrication of alginate composite hydrogel encapsulated retinoic acid and nano Se doped biphasic CaP to augment in situ mineralization and osteoimmunomodulation for bone regeneration

BACKGROUND

Bone tissue engineering endows alternates to support bone defects/injuries that are circumscribed to undergo orchestrated process of remodeling on its own. In this regard, hydrogels have emerged as a promising platform that can confront irregular defects and encourage in situ bone repair.

METHODS

In this study, we aimed to develop a new approach for bone tissue regeneration by developing an alginate based composite hydrogel incorporating selenium doped biphasic calcium phosphate nanoparticles, and retinoic acid. The fabricated hydrogel was physiochemically evaluated for morphological, bonding, and mechanical behavior. Additionally, the biological response of the fabricated hydrogel was evaluated on MC3T3-E1 pre-osteoblast cells.

RESULTS

The developed composite hydrogel confers excellent biocompatibility, and osteoconductivity owing to the presence of alginate, and biphasic calcium phosphate, while selenium presents pro osteogenic, antioxidative, and immunomodulatory properties. The hydrogels exhibited highly porous microstructure, superior mechanical attributes, with enhanced calcification, and biomineralization abilities in vitro.

SIGNIFICANCE

By combining the osteoconductive properties of biphasic calcium phosphate with multifaceted benefits of selenium and retinoic acid, the fabricated composite hydrogel offers a potential transformation in the landscape of bone defect treatment. This strategy could direct a versatile and effective approach to tackle complex bone injuries/defects and present potential for clinical translation.

Carboxymethyl Chitosan Microgels for Sustained Delivery of Vancomycin and Long-Lasting Antibacterial Effects

Carboxymethyl chitosan (CMCh) is a unique polysaccharide with functional groups that can develop positive and negative charges due to the abundant numbers of amine and carboxylic acid groups. CMCh is widely used in different areas due to its excellent biocompatibility, biodegradability, water solubility, and chelating ability. CMCh microgels were synthesized in a microemulsion environment using divinyl sulfone (DVS) as a crosslinking agent. CMCh microgel with tailored size and zeta potential values were obtained in a single stem by crosslinking CMCh in a water-in-oil environment. The spherical microgel structure is confirmed by SEM analysis. The sizes of CMCh microgels varied from one micrometer to tens of micrometers. The isoelectric point of CMCh microgels was determined as pH 4.4. Biocompatibility of CMCh microgels was verified on L929 fibroblasts with 96.5 ± 1.5% cell viability at 1 mg/mL concentration. The drug-carrying abilities of CMCh microgels were evaluated by loading Vancomycin (Van) antibiotic as a model drug. Furthermore, the antibacterial activity efficiency of Van-loaded CMCh microgels (Van@CMCh) was investigated. The MIC values of the released drug from Van@CMCh microgels were found to be 68.6 and 7.95 µg/mL against E. coli and S. aureus, respectively, at 24 h contact time. Disk diffusion tests confirmed that Van@CMCh microgels, especially for Gram-positive (S. aureus) bacteria, revealed long-lasting inhibitory effects on bacteria growth up to 72 h.

Recent advances in carboxymethyl chitosan-based materials for biomedical applications

Chitosan (CS) and its derivatives have been applied extensively in the biomedical field owing to advantageous characteristics including biodegradability, biocompatibility, antibacterial activity and adhesive properties. The low solubility of CS at physiological pH limits its use in systems requiring higher dissolving ability and a suitable drug release rate. Besides, CS can result in fast drug release because of its high swelling degree and rapid water absorption in aqueous media. As a water-soluble derivative of CS, carboxymethyl chitosan (CMC) has certain improved properties, rendering it a more suitable candidate for wound healing, drug delivery and tissue engineering applications. This review will focus on the antibacterial, anticancer and antitumor, antioxidant and antifungal bioactivities of CMC and the most recently described applications of CMC in wound healing, drug delivery, tissue engineering, bioimaging and cosmetics.

Radiation cross-linked gelatin/sodium alginate/carboxymethylcellulose sodium hydrogel for the application as debridement glue paste

Autolytic debridement can accelerate wound healing by removing necrotic tissue. A hydrogel was fabricated from an aqueous solution of gelatin, sodium alginate and carboxymethylcellulose sodium by radiation-induced cross-linking at room temperature, which was aiming at the application of debridement glue paste. The swelling ratio of the debridement glue paste is 30 times to its dry weight, when the weight ratio of gelatin/sodium alginate/carboxymethylcellulose sodium was 2:2:2 and the absorbed dose was 20 kGy, with dose rate of 20 Gy/min. The extrusion and compressive assay have confirmed that it possessed stable mechanical strength, and the weight ratio had little effect on the molecular structure by FTIR and TGA. Cell culture experiments demonstrated the debridement glue pastes with the cytotoxicity of grade 0 or 1 (biosafe). The debridement glue paste group could remove the necrotic tissue within 4 days and showed complete wound healing within 18 days; comparatively, the control group without treatment removed the necrotic tissue within 10 days and showed complete wound healing within 26 days in animal experiments using rabbit scald model. Histologic analysis exhibited that more granulation tissue was observed in debridement glue paste. The result of this study suggested that debridement glue pastes had excellent biocompatibility, could selectively remove necrotic tissue, induced granulation tissue formation and accelerated the wound healing.

Preparation and Characterization of Nanocomposite Scaffolds (Collagen/β-TCP/SrO) for Bone Tissue Engineering

Background

Nowadays, production of nanocomposite scaffolds based on natural biopolymer, bioceramic, and metal ions is a growing field of research due to the potential for bone tissue engineering applications.

Methods

In this study, a nanocomposite scaffold for bone tissue engineering was successfully prepared using collagen (COL), beta-tricalcium phosphate (β-TCP) and strontium oxide (SrO). A composition of β-TCP (4.9 g) was prepared by doping with SrO (0.05 g). Biocompatible porous nanocomposite scaffolds were prepared by freeze-drying in different formulations [COL, COL/β-TCP (1:2 w/w), and COL/β-TCP-Sr (1:2 w/w)] to be used as a provisional matrix or scaffold for bone tissue engineering. The nanoparticles were characterized by X-ray diffraction, Fourier transforms infrared spectroscopy and energy dispersive spectroscopy. Moreover, the prepared scaffolds were characterized by physicochemical properties, such as porosity, swelling ratio, biodegradation, mechanical properties, and biomineralization.

Results

All the scaffolds had a microporous structure with high porosity (~ 95-99%) and appropriate pore size (100-200 μm). COL/β-TCP-Sr scaffolds had the compressive modulus (213.44 ± 0.47 kPa) higher than that of COL/β-TCP (33.14 ± 1.77 kPa). In vitro cytocompatibility, cell attachment and alkaline phosphatase (ALP) activity studies performed using rat bone marrow mesenchymal stem cells. Addition of β-TCP-Sr to collagen scaffolds increased ALP activity by 1.33-1.79 and 2.92-4.57 folds after 7 and 14 days of culture, respectively.

Conclusion

In summary, it was found that the incorporation of Sr into the collagen-β-TCP scaffolds has a great potential for bone tissue engineering applications.

The Application of Multi-Walled Carbon Nanotubes in Bone Tissue Repair Hybrid Scaffolds and the Effect on Cell Growth In Vitro

In this study, composite scaffolds with different multi-walled carbon nanotubes (MWCNTs) content were prepared by freeze-drying. These scaffolds were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), porosity, hydrophilicity, mechanical strength, and degradation. The MWCNTs scaffolds were structurally sound and had porous structures that offered ample space for adherence, proliferation, and differentiation of MC3T3-E1 cells, and also supported the transport of nutrients and metabolic waste. CS/Gel/nHAp/0.3%MWCNTs scaffolds provided the best outcomes in terms of scaffold porosity, hydrophilicity, and degradation rate. However, CS/Gel/nHAp/0.6%MWCNTs scaffolds were found to support the optimal growth, homogenous distribution, and biological activity of MC3T3-E1 cells. The excellent properties of CS/Gel/nHAp/0.6%MWCNTs scaffolds for the adhesion, proliferation, and osteogenesis differentiation of MC3T3-E1 cells in vitro highlights the potential applications of this scaffold in bone tissue regeneration.

Dicalcium Phosphate Anhydrous: An Appropriate Bioceramic in Regeneration of Critical-Sized Radial Bone Defects in Rats

The present study aimed to evaluate and compare the effectiveness of composites of calcium phosphates including β-tri calcium phosphate (β-TCP), dicalcium phosphate anhydrous (DCPA, monetite), mono-calcium phosphate monohydrate (MCPM), and hydroxyapatite (HA) with the chitosan-gelatin-platelet gel (CGP) on the healing of experimentally induced critical size radial bone defects in rats after 8 weeks of injury. Eighty bilateral bone defects were created in the radial bones of 40 adult male Sprague-Dawley rats. The defects were either left empty (untreated or defect group), or treated with autograft, CGP, CGP-DCP, CGP-TCP, CGP/β-TCP/DCPA (CGP-TD), CGP-TD/MCPM (CGP-TDM), and CGP-TDM/HA (CGP-TDMH) scaffolds. The injured forelimbs were evaluated by radiography, gross morphology, three-dimensional computed tomography scanning, histopathology, histomorphometry, scanning electron microscopy, and biomechanical testing. The materials were analyzed using X-ray diffraction to verify the crystalline nature of their structures, and their crystallinity was revealed based on the diffraction peaks achieved from the XRD analysis. The best results were achieved by the CGP-DCP scaffold and the autograft. The CGP-TCP and CGP-TDMH scaffolds were not degraded, while the CGP-DCP, CGP-TDM, CGP-TD, and CGP scaffolds were biodegraded and enhanced bone formation compared with the CGP-TCP and CGP-TDMH groups (P < 0.05). Overall, the CGP-DCP treated defects showed significant improvement in bone formation and union, bone volume, maximum load, and stiffness compared to the CGP group (P < 0.05). It could be concluded that the CGP-DCP scaffold can be considered as a suitable substitute to autograft. In fact, this study demonstrated that DCPA or monetite has high healing potential due to its biocompatibility, biodegradability and biomechanical, osteoconductive and osteoinductive properties of this bioceramic.

Collagen–carboxymethyl cellulose–tricalcium phosphate multi-lamellar cryogels for tissue engineering applications: Production and characterization

Collagen–carboxymethyl cellulose–tricalcium phosphate cryogels were prepared for diverse biomedical applications. Further chemical and structural characterizations were performed by Fourier transform infrared spectra, thermogravimetric analysis, X-ray crystallography, and scanning electron microscopy. The mechanical properties were tested by unconfined compression test. Moreover, hemocompatibility of the cryogels was also evaluated by basic biochemical blood testing. Chemical and structural analysis results demonstrate the achievement of the cross-linking without any major alteration in collagen and carboxymethyl cellulose with a thermally and structurally stable blend formation. Scanning electron micrographs demonstrate the multi-lamellar formation with macro- and micro-pore compositions which can correlate with water uptake results of the cryogels. Hemocompatibility evaluations exhibited that the cryogels are non-toxic and blood-compatible. The overall results including mechanical testing of these tricalcium phosphate–consisting collagen/carboxymethyl cellulose cryogels may have potential use as a material for hard tissue regeneration.

Design of biocomposite materials for bone tissue regeneration

Several synthetic scaffolds are being developed using polymers, ceramics and their composites to overcome the limitations of auto- and allografts. Polymer-ceramic composites appear to be the most promising bone graft substitute since the natural bone itself is a composite of collagen and hydroxyapatite. Ceramics provide strength and osteoconductivity to the scaffold while polymers impart flexibility and resorbability. Natural polymers have an edge over synthetic polymers because of their biocompatibility and biological recognition property. But, very few natural polymer-ceramic composites are available as commercial products, and those few are predominantly based on type I collagen. Disadvantages of using collagen include allergic reactions and pathogen transmission. The commercial products also lack sufficient mechanical properties. This review summarizes the recent developments of biocomposite materials as bone scaffolds to overcome these drawbacks. Their characteristics, in vitro and in vivo performance are discussed with emphasis on their mechanical properties and ways to improve their performance.

Chitosan/CNTs green nanocomposite membrane: synthesis, swelling and polyaromatic hydrocarbons removal

Carbon nanotubes (CNTs) were irradiated in air at 100 kGy under gamma radiations. The Raman spectroscopy of γ-treated CNTs showed distinctive changes in the absorption bands. The CNTs were mixed with blend of chitosan (Cs)/poly (vinyl alcohol) (PVA) and crosslinked with silane. The chemical reactions between the components affected the position and intensities of the infrared bands. Scanning electron micrograph of Cs/CNTs nanocomposite membrane showed the homogeneous dispersion of CNTs in the polymer matrix. The addition of CNTs lowered its swelling in water. Naphthalene (NAPH) was selected as a model compound and its removal was studied using HPLC technique. This membrane showed fast uptake of NAPH and 87% was removed from water within 30 min. The NAPH loaded membrane showed strong chemical interactions and cannot be desorbed. The fast uptake of PAHs and the green nature of this membrane made them suitable candidates for clean-up purposes.

Study of in vitro degradation of brushite cements scaffolds

An interest path to fabricate supports for tissue engineering is to foam calcium phosphate cement's pastes leading to an increase on material's total porosity and interconnectivity which facilitates cells' adhesion, proliferation and differentiation. The aim of this work is to develop scaffolds of brushite cement and to evaluate its in vitro degradation rate. Macroporosity was obtained by foaming the liquid phase with different non-ionic surfactants (Tween 80 and Lutensol ON-110). The foam stability was achieved by adding chitosan. The scaffolds were immersed in Ringers(®) solution during 7, 14, 21 and 28 days and samples' microstructure, weight loss, mechanical resistance and apparent porosity were evaluated. Both scaffolds presented interconnected macropores with sizes ranging from 100 to 360 µm and total porosities higher than 60%. These properties could facilitate cell infiltration, bone growth and vascularization. The scaffolds obtained in this work should be considered as promising materials for application in bone tissue engineering.

Tissue-engineered mandibular bone reconstruction for continuity defects: a systematic approach to the literature

BACKGROUND

Despite significant surgical advances over the last decades, segmental mandibular bone repair remains a challenge. In light of this, tissue engineering might offer a next step in the evolution of mandibular reconstruction.

PURPOSE

The purpose of the present report was to (1) systematically review preclinical in vivo as well as clinical literature regarding bone tissue engineering for mandibular continuity defects, and (2) to analyze their effectiveness.

MATERIALS AND METHODS

An electronic search in the databases of the National Library of Medicine and ISI Web of Knowledge was carried out. Only publications in English were considered, and the search was broadened to animals and humans. Furthermore, the reference lists of related review articles and publications selected for inclusion in this review were systematically screened. Results of histology data and amount of bone bridging were chosen as primary outcome variables. However, for human reports, clinical radiographic evidence was accepted for defined primary outcome variable. The biomechanical properties, scaffold degradation, and clinical wound healing were selected as co-outcome variables.

RESULTS

The electronic search in the databases of the National Library of Medicine and ISI Web of Knowledge resulted in the identification of 6727 and 5017 titles, respectively. Thereafter, title assessment and hand search resulted in 128 abstracts, 101 full-text articles, and 29 scientific papers reporting on animal experiments as well as 11 papers presenting human data on the subject of tissue-engineered reconstruction of mandibular continuity defects that could be included in the present review.

CONCLUSIONS

It was concluded that (1) published preclinical in vivo as well as clinical data are limited, and (2) tissue-engineered approaches demonstrate some clinical potential as an alternative to autogenous bone grafting.