Bone Filler Research Articles

Design of novel functionalized collagen-chitosan-MBG scaffolds for enhancing osteoblast differentiation in BMSCs

Collagen and chitosan are two different kinds of natural biodegradable polymers commonly used in the regeneration of bone defects. Mesoporous bioactive glass (MBG) is a type of favorable bone filler which can effectively constitute an enlarged microenvironment to facilitate an exchange of important factors between the cells and scaffolds. Here we prepared a collagen-chitosan-MBG (C-C-MBG) scaffold which displayed significantly increased proliferation, differentiation and mineralization in bone mesenchymal stem cells (BMSCs). Additionally, we found that the scaffold can stimulate extra-cellular signal regulated kinase 1/2 (Erk1/2) activated Runx2 pathway, which is the predominant signaling pathway involved in osteoblast differentiation. Consistently, we observed that the scaffold can markedly enhance the expression of Type I collagen, Osteopontin (Opn), and Runx2, which are important osteoblastic marker genes implicated in the process of osteoblast differentiation. Therefore, we conclude that the composite scaffold can significantly promote the differentiation of BMSCs into osteoblasts by activating Erk1/2-Runx2 pathway. Our finding thereby implies that the C-C-MBG scaffold can possibly act as a potential biomaterial in the bone regeneration.

Correction to: Hydroxyapatite-based antibacterial bio-nanomaterials: an insight into the synthesis using mussel shell as a calcium source, physicochemical properties, and nanoindentation characteristics

We report the synthesis of hydroxyapatite (HAp)-based antibacterial biomaterials using a mussel shell as a calcium source and by the integration of silver ions via a wet precipitation method. The silver doping at 2 mol% can provide silver-doped carbonated HAp while at 10 mol% can offer silver-doped carbonated HAp/silver oxide nanocomposite. The synthesized Ag-integrated samples exhibit the H (263–903Mpa) and E (0.96–3.31GPa) almost similar to cancellous bone with good antibacterial inhibition on S. aureus (15 ± 02 mm) and E. coli (26 ± 02 mm) growth. Hence, they can be a potential precursor to make bone fillers for the treatment of bone infections.

In Vivo Analyses of Osteogenic Activity and Bone Regeneration Capacity of Demineralized Freeze-Dried Bovine Bone Xenograft: A Potential Candidate for Alveolar Bone Fillers.

Background Deproteinized bovine bone mineral (DBBM) particle is the commonly used bone graft substitute in implant surgery which is mainly osteoconductive and has very slow degradation. Demineralized freeze-dried bovine bone xenograft (DFDBBX) particle is being developed as a novel xenogeneic bone filler. Objectives The study aimed to analyze osteogenic activity and bone-forming capacity of DFDBBX particles compared to DBBM particles in alveolar bone defects in rabbit mandibles models. Material and Methods. This study investigated bone defects whether filled with DBBM particles or DFDBBX particles or left unfilled in 30 rabbit mandibles. Specimens were processed for histology, immunohistochemistry, and micro-CT scanning. Statistical difference was set at a p value < 0.05. Results The quantitative assessment showed a significantly lower number of osteoclasts and a higher number of osteoblasts in the DFDBBX group compared to the DBBM group in 2 and 4 weeks (p < 0.05). Immunostaining analyses showed significantly higher expression of RUNX2, collagen type I, alkaline phosphatase, and osteocalcin in the DFDBBX group compared to the DBBM group in 2 and 4 weeks. Bone healing score in the DFDBBX group was comparable to the DBBM group. Micro-CT presented no significant difference in the volume percentage of the mineralized tissue in the DBBM and DFDBBX groups in spite of the different healing patterns in both groups. Conclusion DFDBBX particles induced higher osteoblastic activities than DBBM particles at the early stage of healing. Meanwhile, the capacity of bone formation in DFDBBX particles was comparable with DBBM particles at the later stage of healing. Considering the limitation of this study, the results presented DFDBBX particles as potential bone filler candidates.

Compressible polyglycolic acid-based nanofibrous matrices as a bone filler: fabrication, physicochemical characterisations, and biocompatibility evaluation

ABSTRACT In this study, amorphous hydroxyapatite (am-HAp) incorporated compressible and nanofibrous polyglycolic acid (PGA-HAp) matrices were fabricated by three-dimensional (3-D) electrospinning. The synthesised am-HAp particles were in the size of 260 ± 45 nm. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses confirmed the chemical and phase structure of the am-HAp particles. Continuous PGA-HAp nanofibers with the mean diameter of 367 ± 70 nm were successfully produced and am-HAp particles were well integrated into the nanofibers. Moreover, XRD and FTIR analyses verified the presence of am-HAp in the PGA nanofibers. The incorporation of the am-HAp to the nanofibers increased the maximum degradation temperature of PGA matrices from 340°C to 362°C. Mechanical analyses confirmed the elasticity of the 3-D PGA matrices. In vitro cell culture studies verified the biocompatibility of the nanofibrous matrices. Hence, 3-D nanofibrous PGA-HAp matrices may be a good alternative to ceramic bone substitutes due to their flexibility and physicochemical properties.

A potential trackable bone filler: Preparation and characterization

AbstractThis study reported the synthesis of fluorescent hydroxyapatite/alginate/carbon quantum dots (HA/Alg/CQDs) nanocomposites via the co‐precipitation technique. The N‐doped CQDs as a new class of fluorescent materials were prepared by the citric acid pyrolysis method, with an average size around 4 nm. Physical, chemical, and optical properties of the synthesized nanocomposites were investigated by X‐ray diffraction (XRD), Fourier‐transformed infrared spectroscopy (FTIR), atomic force microscopy (AFM), field‐emission scanning electron microscopy (FESEM), UV–visible spectroscopy, and photoluminescence (PL) spectroscopy, respectively. The PL spectroscopy data verified the favorable in vitro luminescent emission of the HA/Alg/CQDs nanocomposites in comparison with HA/Alg and HA samples. The XRD patterns of the prepared samples confirmed the formation of crystalline HA in all composites, possessing a Ca/P ratio around 1.5 as obtained by EDX elemental analysis. The FESEM analysis exhibited HA nanoplates that homogeneously distributed throughout the alginate matrix. Therefore, the synthesized nanocomposites could be regarded as potential trackable drug carriers for hard tissue engineering applications.

Strength and Biocompatibility of Heparin-Based Calcium Phosphate Cement Grafted with Ferulic Acid.

The biomimetic synthesis of carbonated apatites by biomolecule-based templates is a promising way for broadening apatite applications in bone tissue regeneration. In this work, heparin was used as an organic template to prepare uniform carbonate-based apatite nanorods (CHA) and graft ferulic acid (F-CHA) for enhanced bone mineralization. Next, by combining calcium phosphate cement (CPC) with different F-CHA/CPC ratios, a new type of injectable bone cement combined with F-CHA bioactive apatite was developed (CPC + F-CHA). The physicochemical properties, biocompatibility, and mineralization potential of the CPC + F-CHA composites were determined in vitro. The experimental results confirmed the preparation of highly biocompatible CHA and the compatibility of F-CHA with CPC. Although CPC + F-CHA composites with F-CHA (2.5 wt%, 5 wt%, and 10 wt%) showed a significant reduction in compressive strength (CS), compositing CPC with 10 wt% F-CHA yielded a CS suitable for orthopedic repair (CS still larger than 30 MPa). Spectroscopic and phase analyses revealed that the phase of the hydrothermally synthesized CHA product was not modified by the heparin template. Injection and disintegration tests indicated that the CPC + F-CHA composites have good biocompatibility even at 10 wt% F-CHA. D1 osteoprogenitor cells were cultured with the composites for 7 days in vitro, and the CPC + 10%F-CHA group demonstrated significantly promoted cell mineralization compared with other groups. Given these results, the use of over 10% F-CHA in CPC composites should be avoided if the latter is to be applied to load-bearing areas. A stress-shielding device may also be recommended to stabilize these areas. These newly developed biocompatible CPC + F-CHA have great potential as osteoconductive bone fillers for bone tissue engineering.

Bioresorbable porous β-tricalcium phosphate chelate-setting cements with poly(lactic-co-glycolic acid) particles as pore-forming agent: fabrication, material properties, cytotoxicity, and in vivo evaluation

ABSTRACT Calcium-phosphate cements (CPCs) have been used as bone filling materials in orthopaedic surgery. However, CPCs are set using an acid-base reaction, and then change into stable hydroxyapatite (HAp) in a living body. Therefore, we developed bioresorbable chelate-setting β-tricalcium phosphate (β-TCP) cements based on surface modifications of inositol phosphate (IP6). In order to improve the bioresorbability, we fabricated IP6/β-TCP cements hybridized with poly(lactic-co-glycolic acid) (PLGA) particles as a pore-forming agent. The compressive strengths of the cements with the amounts of 5 and 10 mass% PLGA particles were 23.2 and 22.8 MPa, respectively. There was no significant difference from cements without PLGA (23.4 MPa). The setting times of the cement specimens with PLGA particles (30 min) were a little longer than those without PLGA particles (26.3 min). The lack of cytotoxicity of the cement specimens was confirmed using osteoblast-like cells (MC3T3-E1). Cylindrical defects were made by drilling into the tibia of mini-pigs and injecting the prepared cement pastes into the defects. Twelve weeks after implantation the specimens were stained with toluidine blue and histologically evaluated. Histological evaluation of cement specimens with PLGA particles showed enhanced bioresorbability. Newly-formed bone was also observed inside cement specimens with PLGA particles. The IP6/β-TCP cement specimens with PLGA particles had excellent material properties, such as injectability, compressive strength, high porosity, no cytotoxicity in vitro, bioresorption and bone formation abilities in vivo. Organic-inorganic hybridized CPCs are expected to be valuable as novel biodegradable paste-like artificial bone fillers.

Mg,Sr-Cosubstituted Hydroxyapatite with Improved Structural Properties

Bone substitute materials require specific properties to make them suitable for implantation, such as biocompatibility and resistance to mechanical loads. Mg,Sr-cosubstituted hydroxyapatite (MgSr-HA) is a promising bone scaffold candidate because its structure is similar to the native bone matrix. However, MgSr-HA materials do not typically withstand thermal treatments over 800 °C, because Mg promotes HA degradation to less stable tricalcium phosphate, a compound that, albeit biocompatible, is not found in bone. We, therefore, designed an ion-exchange process to enrich sintered Sr-HA with Mg and obtain MgSr-HA porous constructs. These materials contained a 0.04–0.08 Mg/Ca molar ratio and a 0.12–0.13 Sr/Ca molar ratio, and had up to 20 MPa of compressive strength, suitable for use as bone fillers or scaffolds. Unlike previous synthetic Mg,Sr-substituted apatite powders, the proposed process did not degrade HA and thus preserved its similarity to bone structure. The obtained material thus combines the presence of bioactive Mg and Sr ions in the HA lattice with a 3D morphological/structural organization that can be customized in pore size and distribution, as well as in mechanical strength, thus potentially covering a wide range of clinical applications.

Development of bioactive sodium alginate/sulfonated polyether ether ketone/hydroxyapatite nanocomposites: Synthesis and in-vitro studies

Developing bioactive composites to fill bone cavities caused by disease, injury or surgery still remains a challenge. The aim of this research was to develop a new nanostructured sodium alginate/sulfonated polyether ether ketone/nano-hydroxyapatite (Alg/SPEEK/HA) biocomposite via a simple chemical precipitation strategy. Structural analysis was carried out using X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) was used to compare the HA content of the composites. The in-vitro bioactivity of the composites with different content of HA was investigated by immersing the specimens in the simulated body fluid (SBF) for 15 days. The presence of HA in the composite structure gave rise to the precipitation of an apatite layer on the surface, which was increased by increase in the content of HA. The formation of the HA layer on the composite surface was scrutinized via FESEM and EDX analysis. Transmission electron microscopy (TEM) images exhibited the presence of HA nanoparticles with less than 30 nm in size. The in-vitro cytotoxicity evaluation was also carried out using MG-63 cells via the MTT assay, which revealed that the cytocompatibility of all specimens was increased with raising the HA content. However, the higher concentration (100 μg/ml) of the composites displayed some toxicity against MG-63 cells. These findings, therefore, proposed that the achieved novel nanocomposites could be regarded as promising materials to serve as bone filler.

Evaluation of a bone filler scaffold for local antibiotic delivery to prevent Staphylococcus aureus infection in a contaminated bone defect

We previously reported the development of an osteogenic bone filler scaffold consisting of degradable polyurethane, hydroxyapatite, and decellularized bovine bone particles. The current study was aimed at evaluating the use of this scaffold as a means of local antibiotic delivery to prevent infection in a bone defect contaminated with Staphylococcus aureus. We evaluated two scaffold formulations with the same component ratios but differing overall porosity and surface area. Studies with vancomycin, daptomycin, and gentamicin confirmed that antibiotic uptake was concentration dependent and that increased porosity correlated with increased uptake and prolonged antibiotic release. We also demonstrate that vancomycin can be passively loaded into either formulation in sufficient concentration to prevent infection in a rabbit model of a contaminated segmental bone defect. Moreover, even in those few cases in which complete eradication was not achieved, the number of viable bacteria in the bone was significantly reduced by treatment and there was no radiographic evidence of osteomyelitis. Radiographs and microcomputed tomography (µCT) analysis from the in vivo studies also suggested that the addition of vancomycin did not have any significant effect on the scaffold itself. These results demonstrate the potential utility of our bone regeneration scaffold for local antibiotic delivery to prevent infection in contaminated bone defects.

Functionalization with a Polyphenol-Rich Pomace Extract Empowers a Ceramic Bone Filler with In Vitro Antioxidant, Anti-Inflammatory, and Pro-Osteogenic Properties.

Oral diseases and periodontitis in particular are a major health burden worldwide, because of their association with various systemic diseases and with conditions such as peri-implantitis. Attempts have been made over the years to reverse bone loss due to the host disproportionate inflammatory response and to prevent failure of dental implants. To this end, the use of biomaterials functionalized with molecules characterized by anti-inflammatory and antioxidant properties could represent a new frontier for regenerating functional periodontal tissues. In this study, a new ceramic granulated biomaterial, named Synergoss Red (SR), functionalized with a polyphenolic mixture extracted from pomace of the Croatina grape variety, is introduced. Following a preliminary in-depth characterization of the extract by HPLC analysis and of the biomaterial surface and composition, we performed evaluations of cytocompatibility and a biological response through in vitro assays. The anti-inflammatory and antioxidant properties of the identified phenolic molecules contained in SR were shown to downregulate inflammation in macrophages, to stimulate in osteoblast-like cells the expression of genes involved in deposition of the early bone matrix, and to mitigate bone remodeling by decreasing the RANKL/OPG ratio. Thanks to its cytocompatibility and assorted beneficial effects on bone regeneration, SR could be considered an innovative regenerative approach in periodontal therapy.

Synthesis, Characterization, Antibacterial Properties, and In Vitro Studies of Selenium and Strontium Co-Substituted Hydroxyapatite.

In this study, as a measure to enhance the antimicrobial activity of biomaterials, the selenium ions have been substituted into hydroxyapatite (HA) at different concentration levels. To balance the potential cytotoxic effects of selenite ions (SeO32−) in HA, strontium (Sr2+) was co-substituted at the same concentration. Selenium and strontium-substituted hydroxyapatites (Se-Sr-HA) at equal molar ratios of x Se/(Se + P) and x Sr/(Sr + Ca) at (x = 0, 0.01, 0.03, 0.05, 0.1, and 0.2) were synthesized via the wet precipitation route and sintered at 900 °C. The effect of the two-ion concentration on morphology, surface charge, composition, antibacterial ability, and cell viability were studied. X-ray diffraction verified the phase purity and confirmed the substitution of selenium and strontium ions. Acellular in vitro bioactivity tests revealed that Se-Sr-HA was highly bioactive compared to pure HA. Se-Sr-HA samples showed excellent antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus carnosus) bacterial strains. In vitro cell–material interaction, using human osteosarcoma cells MG-63 studied by WST-8 assay, showed that Se-HA has a cytotoxic effect; however, the co-substitution of strontium in Se-HA offsets the negative impact of selenium and enhanced the biological properties of HA. Hence, the prepared samples are a suitable choice for antibacterial coatings and bone filler applications.

A bioactive magnesium phosphate cement incorporating chondroitin sulfate for bone regeneration

Magnesium phosphate cement (MPC) has been evaluated as an inorganic bone filler due to its favorable biocompatibility, biodegradability, rapid setting, high initial strength, and osteogenic potential. However, the setting time of MPC is so rapid that it makes it difficult to use in practice, and the clinical properties of MPC could be further be improved by adding bioactive materials. Here we developed novel bioactive chondroitin sulfate (CS)-MPC composites (CS-MPCs) by incorporating different amounts of CS into MPC. The compositions, microstructures, and physiochemical properties of CS-MPCs and their induced in vitro cellular responses and in vivo bone regeneration properties were evaluated. CS-MPCs had a longer setting time, lower hydration temperature, higher compressive strength, and more neural pH than MPC. CS-MPCs demonstrated similar degradation ratios relative to MPC in Tris-HCl solution. CS-MPCs promoted pre-osteoblast cell proliferation, attachment, and differentiation in vitro and enhanced bone formation surrounding implants in vivo. In conclusion, through CS modification, our novel CS-MPCs have improved physiochemical properties that enhance compatibility in vitro and bone regeneration in vivo, making them attractive materials for bone regeneration.

Experimental Drillable Magnesium Phosphate Cement Is a Promising Alternative to Conventional Bone Cements.

Clinically used mineral bone cements lack high strength values, absorbability and drillability. Therefore, magnesium phosphate cements have recently received increasing attention as they unify a high mechanical performance with presumed degradation in vivo. To obtain a drillable cement formulation, farringtonite (Mg3(PO4)2) and magnesium oxide (MgO) were modified with the setting retardant phytic acid (C6H18O24P6). In a pre-testing series, 13 different compositions of magnesium phosphate cements were analyzed concentrating on the clinical demands for application. Of these 13 composites, two cement formulations with different phytic acid content (22.5 wt% and 25 wt%) were identified to meet clinical demands. Both formulations were evaluated in terms of setting time, injectability, compressive strength, screw pullout tests and biomechanical tests in a clinically relevant fracture model. The cements were used as bone filler of a metaphyseal bone defect alone, and in combination with screws drilled through the cement. Both formulations achieved a setting time of 5 min 30 s and an injectability of 100%. Compressive strength was shown to be ~12–13 MPa and the overall displacement of the reduced fracture was <2 mm with and without screws. Maximum load until reduced fracture failure was ~2600 N for the cements only and ~3800 N for the combination with screws. Two new compositions of magnesium phosphate cements revealed high strength in clinically relevant biomechanical test set-ups and add clinically desired characteristics to its strength such as injectability and drillability.

Exosome-Functionalized Ceramic Bone Substitute Promotes Critical-Sized Bone Defect Repair in Rats.

Ceramic biomaterials are promising alternatives to bone autografts. However, limited bioactivity affects their performance. Therefore, bioactive molecules and cells are often added to enhance their performance. Exosomes have emerged as cell-secreted vesicles, delivering proteins, lipids, and nucleic acids in a paracrine/endocrine fashion. We studied two complementary aspects required for exosome activity/therapy using purified exosomes: first, the intracellular uptake of labeled exosomes and second, the influence of delivered exosomes on cell behavior. Origin-specific differences in the characteristics of purified exosomes, quantification of time-dependent intracellular uptake of PKH-26-labeled exosomes by mesenchymal stem cells (MSCs) and preosteoblasts, and influence on cell behavior were evaluated. Furthermore, exosomes from osteoblasts and MSCs cultured under normal and osteogenic environments were isolated. There is little data available on the concentration and dose of exosomes required for bone regeneration. Therefore, equal amounts of quantified exosomes were implanted in vivo in rat tibia critical defects using a calcium sulfate-nano-hydroxyapatite nanocement (NC) bone filler as the carrier. Bone regeneration was quantified using micro-computed tomography and histology. Along with inducing early maturation and mineral deposition by primary preosteoblasts in vitro, exosome treatment also demonstrated a positive effect on bone mineralization in vivo. Our study concludes that providing a local delivery of exosomes loaded onto a slowly resorbing NC bone filler can provide a potential alternate to autografts as a bone substitute.

Biomechanical Evaluation of an Injectable Alginate / Dicalcium Phosphate Cement Composites for Bone Tissue Engineering

Biocompatible dicalcium phosphate (DCP) cements are widely used as bone repair materials. In this study, we aimed to investigate the impact of different amounts of sodium alginate (SA) on the microstructural, mechanical, and biological properties of DCP cements. Beta-tricalcium phosphate (β-TCP) was prepared using a microwave-assisted wet precipitation system. Lattice parameters of the obtained particles determined from X-ray diffraction (XRD), were in good match with a standard phase of β-TCP. Scanning electron microscopy (SEM) examination revealed that the particles were in globular shape. Furthermore, all functional groups of β-TCP were also detected using Fourier-transform infrared spectroscopy (FTIR) spectra. DCP cement (pure phase) was synthesized using monocalcium phosphate monohydrate (MCPM)/β-TCP powder mixture blended with 1.0 mL of water. SA/DCP cement composites were synthesized by dissolving different amounts of SA into water (1.0 mL) to obtain different final concentrations (0.5%, 1%, 2% and 3%). The prepared cements were characterized with XRD, SEM, FTIR and Thermogravimetric analysis (TGA). XRD results showed that pure DCP and SA/DCP cements were in a good match with Monetite phase. SEM results confirmed that addition of SA inhibited the growth of DCP particles. Setting time and injectability behaviour were significantly improved upon increasing the SA amount into DCP cements. In vitro biodegradation was evaluated using Simulated body fluid (SBF) over 21 days at 37 °C. The highest cumulative weight loss (%) in SBF was observed for 2.0% SA/DCP (about 26.52%) after 21 days of incubation. Amount of Ca2+ ions released in SBF increased with the addition of SA. DCP and SA/DCP cements showed the highest mechanical strength after 3 days of incubation in SBF and declined with prolonged immersion periods. In vitro cell culture experiments were conducted using Dental pulp stem cells (DPSCs). Viability and morphology of cells incubated in extract media of DCP and SA/DCP discs after 24 h incubation was studied with MTT assay and fluorescence microscopy imaging, respectively. All cements were cytocompatible and viability of cells incubated in extracts of cements was higher than observed in the control group. Based on the outcomes, SA/DCP bone cements have a promising future to be utilized as bone filler.

Eggshell derived CaO-Portland cement antibacterial composites

Eggshells have been reported to generate huge tons of waste globally owing to their increasing consumption. Apart from its dietary benefits, the use of eggshell waste as a catalyst, filler in soil-cement bricks, dental cement, bone filler, etc. has been widely reported. This study uses a heat-treated eggshell by extracting calcium oxide, CaO, to prepare cement antibacterial composites. Thermogravimetric Analysis (TGA), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS or EDX), and Fourier transform infrared (FTIR) characterization techniques were used to understand the changes in the eggshell upon heat-treatment. Pure CaO obtained by heating eggshell at 900 °C was also examined for antibacterial activity against E.Coli and was found to be highly effective. CaO derived from eggshell was replaced with 5%, 10%, and 15% of cement weight of mortar and studied for antibacterial activity. It was observed that with increasing CaO content, the capacity of the specimen to kill bacteria increased on the surface. This usage of heat-treated eggshell in mortar can be a potential antibacterial composite. The novelty of this work highlights the use of heat-treated eggshell in preparation of antibacterial composites.

A Method to Prepare Hollow Spherical Hydroxyapatite Granules for Drug Delivery

Abstract A suitable microenvironment provided by artificial granule scaffold plays a critical regulatory role in bone repairing progression. Till now, it is still a challenge to prepare large hydroxyapatite granules (millimetre level) which provide beneficial physical and chemical stimulation for bone reconstruction. Herein, we developed a facile synthetic strategy for synthesizing hydroxyapatite granules by a repaid gelling method. Also, the satisfying drug-releasing behavior of these granules further proves their potential prospect for bone tissue engineering as bone filler.

Filament extrusion of bioresorbable PDLGA for additive manufacturing utilising diatom biosilica to inhibit process-induced thermal degradation

Bone scaffolds are often fabricated by initially producing custom-made filaments by twin-screw extruder and subsequently fabricating into 3D scaffolds using fused deposition modelling. This study aims to directly compare the effect of two alternative silica-rich filler materials on the thermo-mechanical properties of such scaffolds after extrusion and printing. Poly (DL-lactide-co-glycolide) (PDLGA) was blended with either 45S5 Bioglass (5 wt %) or Biosilica (1 and 5 wt%) isolated from Cyclotella meneghiniana a freshwater diatom were tested. Diatom-PDLGA was found to have similar mechanical strength and ductility to pure-PDLGA, whereas Bioglass-PDLGA was found induce a more brittle behaviour. Bioglass-PDLGA was also found to have the lowest toughness in terms of energy absorption to failure. The TGA results suggested that significant thermal degradation in both the Bioglass filaments and scaffolds had occurred as a result of processing. However, diatom biosilica was found to inhibit thermal degradation of the PDLGA. Furthermore, evidence suggested the agglomeration of Bioglass particles occurred during processing the Bioglass-PDLGA filaments. Overall, diatom biosilica was found to be a promising candidate as a bone filler additive in 3D printed PDLGA scaffolds, whereas Bioglass caused some potentially detrimental effects on performance.

Influence of silicon carbide on structural, optical and magnetic properties of Wollastonite/Fe2O3 nanocomposites

The influence of adding 10, 20 and 30% molar ratio of silicon carbide (SiC) separately to a composite of wollastonite (W) with a fixed content of 10%Fe2O3 prepared by wet precipitation method was studied. The crystal structure of the annealed composite powders was inspected by X-ray diffraction (XRD); revealing multi-phase structure. The highest estimated crystallite size investigated by Scherrer equation of W, SiC, WFe:SiC10, WFe:SiC20 and WFe:SiC30 were 53.89, 54.6, 56.3, 48.5 and 54.6 nm respectively; demonstrating the formation of nanocomposites. Particles shape, size and crystallinity of the samples were studied using high resolution transmission electron microscope (HR-TEM). The band gap Eg values of the nanocomposites increased with SiC content having an intermediate value that lies between that of γ-Fe2O3 (maghemite) and SiC. Ferromagnetic and paramagnetic contributions were observed in the magnetic hysteresis loops for the composites. This study highlighted that the coercive field (Hci) of the composites improved with increasing the SiC content. The innovative wollastonite/Fe2O3/SiC with amended magnetic properties elicited attention due to their promising application in bone filler and industrial purposes.