Phosphate Particles Research Articles

Macroporous Nanostructured Calcium Phosphate/Chitosan-Gelatin Composite Bone Tissue Engineering Scaffold

Background: Tissue engineering is an emerging technology developed for the therapeutic reconstruction of damaged tissue. Objective: In this study, a ceramic/polymer nanocomposite bone tissue engineering scaffold was prepared by coating a tetracalcium phosphate/dicalcium phosphate mixture slurry on a porous 3D chitosan-gelatin construction. Methods: The phase composition, structural groups, and morphological aspects of the samples were characterized. Furthermore, the 3D composite scaffold was immersed in simulated body fluid (SBF) solution at 37ºC for various periods to track its compositional and structural changes. Results: Based on the results, the coated layer is composed of needle-like carbonated apatite nanosized crystals with some tetracalcium phosphate/dicalcium phosphate initial materials. The nanocomposite was porous with an average macropore size of about 410 μm. The in vitro tests revealed that the composition of the coated layer tends to be apatite crystals, which are similar to natural bone in terms of chemistry and morphology. Conclusion: The results suggest that a simple coating of chitosan-gelatin scaffolds using reactive calcium phosphate particles may introduce a novel nanocomposite scaffold with improved mechanical strength, bioactivity, and osteoconductivity.

Advanced Synthetic Scaffolds Based on 1D Inorganic Micro-/Nanomaterials for Bone Regeneration.

Inorganic nanoparticulate biomaterials, such as calcium phosphate and bioglass particles, with chemical compositions similar to that of the inorganic component of natural bone, and hence having excellent biocompatibility and bioactivity, are widely used for the fabrication of synthetic bone graft substitutes. Growing evidence suggests that structurally anisotropic, or 1D inorganic micro-/nanobiomaterials are superior to inorganic nanoparticulate biomaterials in the context of mechanical reinforcement and construction of self-supporting 3D network structures. Therefore, in the past decades, efforts have been devoted to developing advanced synthetic scaffolds for bone regeneration using 1D micro-/nanobiomaterials as building blocks. These scaffolds feature extraordinary physical and biological properties, such as enhanced mechanical properties, super elasticity, multiscale hierarchical architecture, extracellular matrix-like fibrous microstructure, and desirable biocompatibility and bioactivity, etc. In this review, an overview of recent progress in the development of advanced scaffolds for bone regeneration is provided based on 1D inorganic micro-/nanobiomaterials with a focus on their structural design, mechanical properties, and bioactivity. The promising perspectives for future research directions are also highlighted.

GelMA/TCP nanocomposite scaffold for vital pulp therapy

Pulp capping is a necessary procedure for preserving the vitality and health of the dental pulp, playing a crucial role in preventing the need for root canal treatment or tooth extraction. Here, we developed an electrospun gelatin methacryloyl (GelMA) fibrous scaffold incorporating beta-tricalcium phosphate (TCP) particles for pulp capping. A comprehensive morphological, physical-chemical, and mechanical characterization of the engineered fibrous scaffolds was performed. In vitro bioactivity, cell compatibility, and odontogenic differentiation potential of the scaffolds in dental pulp stem cells (DPSCs) were also evaluated. A pre-clinical in vivo model was used to determine the therapeutic role of the GelMA/TCP scaffolds in promoting hard tissue formation. Morphological, chemical, and thermal analyses confirmed effective TCP incorporation in the GelMA nanofibers. The GelMA+20%TCP nanofibrous scaffold exhibited bead-free morphology and suitable mechanical and degradation properties. In vitro, GelMA+20%TCP scaffolds supported apatite-like formation, improved cell spreading, and increased deposition of mineralization nodules. Gene expression analysis revealed upregulation of ALPL, RUNX2, COL1A1, and DMP1 in the presence of TCP-laden scaffolds. In vivo, analyses showed mild inflammatory reaction upon scaffolds’ contact while supporting mineralized tissue formation. Although the levels of Nestin and DMP1 proteins did not exceed those associated with the clinical reference treatment (i.e., mineral trioxide aggregate), the GelMA+20%TCP scaffold exhibited comparable levels, thus suggesting the emergence of differentiated odontoblast-like cells capable of dentin matrix secretion. Our innovative GelMA/TCP scaffold represents a simplified and efficient alternative to conventional pulp-capping biomaterials. Statement of significanceVital pulp therapy (VPT) aims to preserve dental pulp vitality and avoid root canal treatment. Biomaterials that bolster mineralized tissue regeneration with ease of use are still lacking. We successfully engineered gelatin methacryloyl (GelMA) electrospun scaffolds incorporated with beta-tricalcium phosphate (TCP) for VPT. Notably, electrospun GelMA-based scaffolds containing 20% (w/v) of TCP exhibited favorable mechanical properties and degradation, cytocompatibility, and mineralization potential indicated by apatite-like structures in vitro and mineralized tissue deposition in vivo, although not surpassing those associated with the standard of care. Collectively, our innovative GelMA/TCP scaffold represents a simplified alternative to conventional pulp capping materials such as MTA and Biodentine™ since it is a ready-to-use biomaterial, requires no setting time, and is therapeutically effective.

Reuse of waste acid from titanium dioxide industry: Efficient synthesis and functional exploration of titanium phosphate

The titanium phosphate particles were prepared from acidic wastewater containing titanium by a simple and efficient method, and characterized by XRD, SEM, FTIR and XPS. The results revealed that the titanium phosphate was a porous amorphous material with a high specific surface area. Its main chemical composition was determined to be Ti(OH)2(HPO4)•1·.5H2O based on the Ti-O skeleton and phosphate group. Due to its structural similarity to anatase titanium dioxide, it displayed excellent UV shielding ability along with ample modification potential. Additionally, it demonstrated strong selective adsorption capacity for thorium under acidic conditions, achieving a saturation adsorption capacity of 159.24 mg/g. The adsorption process followed the Langmuir isotherm and Pseudo-second-order kinetic model. The presence of phosphate groups and Ti-O bonds played pivotal roles in the-based adsorption mechanism dominated by ion exchange processes. Furthermore, desorption experiments confirmed its exceptional stability and reusability for practical applications.

Yttrium speciation variability in bauxite residues of various origins, ages and storage conditions

Bauxite residues (BRs) are highly alkaline wastes generated during alumina production from bauxite ore. Billions of tons have been accumulating worldwide for more than 100 years, they are stored in various forms, and pose environmental and societal issues. At the same time, BRs are promising secondary sources for the production of critical metals including rare earth elements (REEs). However, knowledge on REE speciation is lacking, and is consequently an obstacle to the development of large-scale extraction process. This study analyses the influence of origin of the bauxite ore (lateritic or karstic), the storage conditions and storage time on the properties of ten BR samples, with a particular focus on the speciation of yttrium, which is used as a proxy to identify the behaviour of heavy REE. A multi-scale approach linked yttrium speciation and the origin of the bauxite ore whereas no major variation was observed as a function of storage conditions or ageing of the BRs. Yttrium is mainly found in the form of xenotime phosphate particles in BRs of lateritic origin, while in karstic BRs, the majority of yttrium is probably adsorbed or incorporated into other minerals including iron oxyhydroxide and hydroxyapatite minerals.

A Review on Calcinosis cutis

Calcinosis (hydroxyapatite but also calcium and phosphate particle depositions) inside the matrix proteins of both the skin and subcutaneous stroma is just a regularly attended personification like pediatric and adult immune-mediated chronic inflammatory pathogens, particularly system-wide patients with multiple, physiological conditions, mingled soft tissue illness, as well as autoimmune disorder providing the ability. Listed here, researchers overview classifying like mainly characterized, illustrate processes which may make a contribution towards the pathophysiologic like mainly characterized, but also sum up this same scientific proof trying to evaluate non - non-pharmacologic as well as pharmacodynamic intervention and prevention again for remedy like mainly characterized. calcinosis cutis has been best described even by the accumulation of irresolvable calcium ions within the epidermis as well as subcutaneous. These same symptoms seem to be kept separate into 5 subgroups: dystrophic calcification, metastatic calcification, idiopathic calcification, iatrogenic calcification, as well as calciphylaxis. dysplastic calcium deposits would seem because of municipalities' cellular damage as well as the regular calcium and phosphorus layers throughout the plasma. Distant metastasis calcified seems to be best described by such irregular potassium as well as phosphorous various metabolic, resulting in this same formation of calcium through skin lesions as well as subcutaneous. Undiagnosed calcified takes place without even any subcutaneous tissue destruction as well as a particular disease. Epidermis calcified throughout autoimmune mainly characterized syndrome is a rare is indeed a secondary effect like therapeutic. Calciphylaxis introduced for container ship calcium deposits primarily affects the vascular system of both the dermal layer as well as subcutaneous adipose. Disruptions through calcium and phosphorus biotransformation as well as congenital hypothyroidism can indeed be recognized.

Evaluation of Recombinant Human Platelet Derived Growth Factor (rhPDGF-BB) Along with Tricalcium Phosphate (β-TCP) in Impacted Mandibular 3rd Molar Sockets

Aim: The aim of this study was to evaluate efficacy of Recombinant Human Platelet derived Growth Factor (rhPDGF-BB) mixed with Tricalcium Phosphate (β-TCP) particles in mandibular 3rd molar extraction socket for bone regeneration. Setting And Design: A comparative clinical trial consisting of 10 patients who wanted to undergo the surgical extraction of mandibular 3rd molar bilaterally, were undertaken in the institutional settings, where in each patient one side of lower third molar extraction site was kept as control and in the other side graft material was used, after the approval from the institutional ethical committee. Materials And Methods: In this study 10 patients were included with mean age of 28.3 years (Ranging from (20-35 years). These were 4 male and 6 female patients. In each patient one side of lower third molar extraction site was kept as control site and in the other side graft material was used kept as study site. Hence 10 control sites were compared with 10 study sites. Selection of site for placement of graft was done randomly. In 6 patients study site was on right side and in 4 patients study site was on left side. Clinical parameters like pain, facial swelling, total number of analgesic tablets required evaluated at 48hrs and at 7th day. While, radiographically bone density was evaluated after 1st and 3rd month postoperatively. Other parameters like infection, sinus discharge, wound dehiscence, dry socket or graft leakage were also observed. Results: rh PDGF with β – TCP when used in mandibular third molar extraction socket results in rapid bone regeneration seen via increased bone density. It also results in less post-operative discomfort to the patient like pain and swelling. Complications like infection, sinus discharge, wound dehiscence, dry socket or graft leakage were not encountered and the tissue showed good acceptance with no graft rejection. Conclusions: The rh PDGF/β – TCP combination is a novel bone grafting material with excellent results and should be included in the armamentarium when bone defect is encountered.

Sound-based assembly of three-dimensional cellularized and acellularized constructs.

Herein we show an accessible technique based on Faraday waves that assist the rapid assembly of osteoinductive β-Tricalcium phosphate (β-TCP) particles as well as human osteoblast pre-assembled in spheroids. The hydrodynamic forces originating at 'seabed' of the assembly chamber can be used to tightly aggregate inorganic and biological entities at packing densities that resemble those of native tissues. Additionally, following a layer-by-layer assembly procedure, centimeter scaled osteoinductive three-dimensional and cellularized constructs have been fabricated. We showed that the intimate connection between biological building blocks is essential in engineering living system able of localized mineral deposition. Our results demonstrate, for the first time, the possibility to obtain three-dimensional cellularized and acellularized anisotropic constructs using Faraday waves.

Multiscale multimodal characterization and simulation of structural alterations in failed bioprosthetic heart valves.

Calcific degeneration is the most frequent type of heart valve failure, with rising incidence due to the ageing population. The gold standard treatment to date is valve replacement. Unfortunately, calcification oftentimes re-occurs in bioprosthetic substitutes, with the governing processes remaining poorly understood. Here, we present a multiscale, multimodal analysis of disturbances and extensive mineralisation of the collagen network in failed bioprosthetic bovine pericardium valve explants with full histoanatomical context. In addition to highly abundant mineralized collagen fibres and fibrils, calcified micron-sized particles previously discovered in native valves were also prevalent on the aortic as well as the ventricular surface of bioprosthetic valves. The two mineral types (fibres and particles) were detectable even in early-stage mineralisation, prior to any macroscopic calcification. Based on multiscale multimodal characterisation and high-fidelity simulations, we demonstrate that mineral occurrence coincides with regions exposed to high haemodynamic and biomechanical indicators. These insights obtained by multiscale analysis of failed bioprosthetic valves serve as groundwork for the evidence-based development of more durable alternatives. STATEMENT OF SIGNIFICANCE: Bioprosthetic valve calcification is a well-known clinically significant phenomenon, leading to valve failure. The nanoanalytical characterisation of bioprosthetic valves gives insights into the highly abundant, extensive calcification and disorganization of the collagen network and the presence of calcium phosphate particles previously reported in native cardiovascular tissues. While the collagen matrix mineralisation can be primarily attributed to a combination of chemical and mechanical alterations, the calcified particles are likely of host cellular origin. This work presents a straightforward route to mineral identification and characterization at high resolution and sensitivity, and with full histoanatomical context and correlation to hemodynamic and biomechanical indicators, hence providing design cues for improved bioprosthetic valve alternatives.

Evaluation of the acute toxicity by Artemia salina of hydroxyapatite nanoparticles obtained via sol-gel in an aqueous medium without using additives

Hydroxyapatite (Hap) is one of the most important calcium phosphate bioceramics applied to bone tissue regeneration. Synthesizing Hap nanoparticles from easily accessible and low-cost alternative sources of calcium precursors remains a challenge, as well as defining an ideal and reproducible synthesis route without using additives to control the pH of the reaction and entirely performed at room temperature. This study proposes a route for the synthesis of hydroxyapatite by the sol-gel method without the addition of additives for pH control, carried out at room temperature. The Hap samples were characterized by FTIR, XRD, SEM, and BET. The synthesized Hap presented a spherical morphology without the formation of unwanted phases or residues. Samples calcined at 600 and 750 °C resulted in stoichiometric hydroxyapatite with 100% purity and average particle sizes of 24 and 53 nm, respectively. On the other hand, the samples calcined at 900 and 1050 °C presented a specific content of β-calcium phosphate and average particle sizes of 118 and 732 nm, respectively. Acute toxicity was evaluated by Artemia salina nauplii instar I and II for 24 and 48 h of exposure. The tests were conducted on 10, 100, and 1000 ppm of Hap dissolutions. The highest death rate and more significant morphological alterations were observed in A. salina nauplii instar II, exposed to Hap at a concentration of 1000 ppm for 48 h.

Obtaining biocompatible polymeric scaffolds loaded with calcium phosphates through the digital light processing technique

In the present work, scaffolds with gyroid TPMS geometry were obtained from a commercial resin of acrylic nature loaded with 0.5% and 1% w/V of calcium phosphate nanoparticles through DLP. The scaffolds obtained presented Young's Modulus between 300 and 400 MPa, which makes them suitable for bone applications. The surface treatment by oxygen plasma carried out on the scaffolds resulted in a notable improvement in the wettability of the surfaces, which favours cell adhesion on the surface of the materials. The in vitro bioactivity assay conducted on the resin/calcium phosphate particles composite material showed that an apatitic layer forms on the surface of the samples from the third day of exposure to simulated body fluid (SBF), indicating that the composite material has in vitro bioactive behaviour. Biological tests demonstrated that the material is not cytotoxic and favours cell adhesion and that the gyroid geometry promotes cell proliferation.Graphical abstract

Novel Biocement/Honey Composites for Bone Regenerative Medicine.

New biocements based on a powdered mixture of calcium phosphate/monetite (TTCPM) modified with the addition of honey were prepared by mixing the powder and honey liquid components at a non-cytotoxic concentration of honey (up to 10% (w/v)). The setting process of the cements was not affected by the addition of honey, and the setting time of ~4 min corresponded to the fast setting calcium phosphate cements (CPCs). The cement powder mixture was completely transformed into calcium-deficient nanohydroxyapatite after 24 h of hardening in a simulated body fluid, and the columnar growth of long, needle-like nanohydroxyapatite particles around the original calcium phosphate particles was observed in the honey cements. The compressive strength of the honey cements was reduced with the content of honey in the cement. Comparable antibacterial activities were found for the cements with honey solutions on Escherichia coli, but very low antibacterial activities were found for Staphylococcus aureus for all the cements. The enhanced antioxidant inhibitory activity of the composite extracts was verified. In vitro cytotoxicity testing verified the non-cytotoxic nature of the honey cement extracts, and the addition of honey promoted alkaline phosphatase activity, calcium deposit production, and the upregulation of osteogenic genes (osteopontin, osteocalcin, and osteonectin) by mesenchymal stem cells, demonstrating the positive synergistic effect of honey and CPCs on the bioactivity of cements that could be promising therapeutic candidates for the repair of bone defects.

A high corrosion-resistant waterborne epoxy resin coating improved by addition of multi-interface structured zinc phosphate particles

In the present study, a three-dimensional multi-interface structured zinc phosphate particle with large specific surface area was prepared by regulating the zinc phosphate crystal growth process, which was applied to develop a waterborne epoxy resin coating with better corrosion resistance. The results reveal that the multi-interface structured zinc phosphate particles could well coalesce with epoxy resin. Compared with the waterborne coating doped with and without two-dimensional zinc phosphate sheets, the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating has highest corrosion potential, lowest corrosion current density and the highest low-frequency impedance, which indicates the obvious benefits of multi-interface structured zinc phosphate particles on corrosion resistance. Moreover, the electrochemical properties tests on the waterborne epoxy resin coatings immersed in salt solution for 3000 h demonstrate that the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating almost has no changes but the other waterborne epoxy resin coatings decrease obviously. The surface characterization on the corroded waterborne epoxy resin coatings reveal that the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating possesses the relative integrated surface, while the inner corrosion has occurred in other coatings. The waterborne epoxy resin coatings with different additives sprayed on Al alloy surface could obtain the adhesion strength between 6.21 and 6.81 MPa, and the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating possesses the maximum value. Even after the salt solution immersion for 3000 h, the multi-interface structured zinc phosphate particles doped waterborne epoxy resin coating still remains the adhesion strength above 6.21 MPa. Such excellent corrosion resistance should be ascribed to the cooperation of strengthened physical inhibition effect, decreased polar channel and complexation reaction by multi-interface structured zinc phosphate particles.

Self-reinforced aluminum phosphate framework/bismaleimide composites with double cross-linking hybrid structures

In this work, aluminum phosphate framework (APF)/ bismaleimide (BMI) hybrid composites with the double cross-linking hybrid (DCH) structures are successfully fabricated in right conditions. Herein, the three-dimensional (3D) structures of APF play the critical role in the reinforced effects of mechanical properties. Aim to strengthen the APF/BMI composites, the lamellar aluminum phosphate (LAP) particles are chosen by self-reinforced effects. From the perspective formation of the LAP-APF complex, the structures of the LAP-APF/BMI composites are investigated and the mechanical and dielectric properties are evaluated. Finally, the reinforced mechanism is also analyzed. The maximum flexural strength can approximately reach up to 170.46 MPa, and the dielectric constant further decreased after the addition of LAP particles. There are helpful for designing the higher performance inorganic/organic hybrid composites and expanding their applications.

Castor oil-based gel containing calcium phosphate/sorbitan monopalmitate nanocomposite as proof of concept for tooth sensitivity treatment

Desensitizing gel has been used increasingly to produce stable minerals and occlude exposed dentine tubules in order to eliminate dentine hypersensitivity. In this study, calcium phosphate particles were synthesized in different ratios in the presence of a mixture of sorbitan monopalmitate and castor oil at 60 °C to generate water-in-oil emulsion, which was followed by gel formation. The rheological properties of the prepared gel samples were studied, and they showed weak gel behavior. The smallest particle size of calcium phosphate embedded in the gel sample was approximately 0.2 µm. This type of gel can release calcium and phosphate ions to initiate ion binding on the dental surface, thereby resulting in complete occlusion of the dentinal tubule approximately 10 h after the gel application. Moreover, cytotoxicity test revealed that the gel exhibited good compatibility with human cells at extract concentrations of < 1 mg/mL. In conclusion, the most effective gel CO-SMP4 could be utilized for the production of tooth desensitizing gels meant for home use that can effectively alleviate dentine hypersensitivity.

Enhanced injectability of aqueous β-tricalcium phosphate suspensions through PAA incorporation, gelling and preshearing

The major shortcoming of aqueous calcium phosphate suspensions used in biomedical applications is their unstable flow during delivery by mechanical means. In this study, microstructural changes and the resulting flow instabilities of aqueous β-TCP suspensions are demonstrated under both pressure-induced and drag-induced flow regimes and then remedied with the incorporation and subsequent gelling and preshearing of Carbopol 940, a biocompatible hydrogel. Mixing and dispersion of calcium phosphate particles into the hydrogel matrix was not efficient under simple agitation conditions. Swelling of the polymer chains was induced at approximately pH = 9.0 by water and particle intrusion within the opened-up coil structure due to deprotonation of the carboxylic acid groups by NaOH. As a result the composite material underwent a rapid viscoplastic transition into a doughy state which was not amenable to further processing without preshearing. Manual kneading converted the material into viscous state and enhanced the flow behavior significantly. Preshearing and probing the microstructure by mechanical spectrometer revealed multiple microstructural mechanisms responsible for the observed stable flow behavior, including improved dispersion of the particles, attrition of the polymeric network into microgel domains, enhanced adhesion and lubrication between the solid and liquid phase, crosslinking of the polymeric network. The net effect of these probable mechanisms was stiffening of the composite matrix, mobilization of solid particles and a marked enhancement in the stability of pressure-induced flow. The resistance of the material to liquid phase migration and its ability to undergo wall-slip and relax under stress were confirmed by simultaneous capillary rheometry and thermogravimetric analyses. The processing method enables improvements in the delivery of this composite material for injection and direct ink writing of scaffolds.

Photocurable 3D-printed PMBG/TCP biphasic scaffold mimicking vasculature for bone regeneration.

Mesoporous bioglass (MBG) with excellent osteointegration, osteoinduction, and biodegradability is a promising material for bone regeneration. However, its clinical application is hindered by complex processing and a lack of personalization, low mechanical strength, and uncontrollable degradation rate. In this study, we developed a double-bond-functionalized photocurable mesoporous bioglass (PMBG) sol that enabled ultrafast photopolymerization within 5 s. By further integrating nanosized tricalcium phosphate (TCP) particles through three-dimensional (3D) printing technology, we fabricated personalized and highly porous PMBG/TCP biphasic scaffolds. The mechanical properties and degradation behavior of the scaffolds were regulated by varying the amount of TCP doping. In vitro and in vivo experiments verified that PMBG/TCP scaffolds slowly released SiO44- and Ca2+, forming a vascularized bone regeneration microenvironment within the fully interconnected pore channels of the scaffold. This microenvironment promoted angiogenesis and accelerated bone tissue regeneration. Overall, this work demonstrates the solution to the problem of complex processing and lack of personalization in bioglass scaffolds, and the developed PMBG/TCP biphasic scaffold is an ideal material for bone regeneration applications with broad clinical prospects.

A Perfluorocarbon-Coated ZrP Cation Exchanger with Excellent Ammonium Selectivity and Chemical Stability: An Oral Sorbent for End-Stage Kidney Disease (ESKD).

An oral sorbent to remove NH4+ within the small intestine of end-stage kidney disease (ESKD) patients could reduce blood urea levels and diminish their dialysis treatment burden. But current sorbent materials like amorphous zirconium phosphate particles Zr(HPO4)2·H2O (ZrP) lack the selectivity to remove NH4+ in water solution with other competing ions. Our previous work found that a gas-permeable, hydrophobic polydimethylsiloxane (PDMS) coating on ZrP improved the material's selectivity for NH4+. However, a competing ion Ca2+ was still removed by PDMS-coated ZrP sorbent, and the permeability of the PDMS coating to Ca2+ was increased after low-pH stomach-like condition exposure. An alternative hydrophobic and gas permeable coating has been investigated─perfluorooctyltriethoxysilane (FOTS). The coating was attached in place of PDMS to a tetraethyl orthosilicate-coated ZrP surface. Surface atomic composition analysis and scanning electron microscopy observation verified the successful application of the FOTS coating. Water contact angle analysis validated the FOTS coating was hydrophobic (145.0 ± 3.2°). In vitro competing ion studies indicated the FOTS coating attached to ZrP increased NH4+ removal by 53% versus uncoated ZrP. FOTS offers complete selectivity for NH4+ over Ca2+ with similar NH4+ capacity as the previous PDMS coating. Moreover, FOTS-coated ZrP maintained NH4+ removal capacity and selectivity after the acid exposure study, indicating excellent acid resistance while NH4+ selectivity of ZrP-PDMS decreased by 72%. The results suggested that FOTS-coated ZrP is promising as an oral sorbent for ESKD patients.

Poly(3-hydroxybutyrate) (PHB) and Polycaprolactone (PCL) Based Blends for Tissue Engineering and Bone Medical Applications Processed by FDM 3D Printing.

In the presented work, poly(3-hydroxybutyrate)-PHB-based composite blends for bone medical applications and tissue engineering are prepared and characterized. PHB used for the work was in two cases commercial and, in one case, was extracted by the chloroform-free route. PHB was then blended with poly(lactic acid) (PLA) or polycaprolactone (PCL) and plasticized by oligomeric adipate ester (Syncroflex, SN). Tricalcium phosphate (TCP) particles were used as a bioactive filler. Prepared polymer blends were processed into the form of 3D printing filaments. The samples for all the tests performed were prepared by FDM 3D printing or compression molding. Differential scanning calorimetry was conducted to evaluate the thermal properties, followed by optimization of printing temperature by temperature tower test and determination of warping coefficient. Tensile test, three-point flexural test, and compression test were performed to study the mechanical properties of materials. Optical contact angle measurement was conducted to determine the surface properties of these blends and their influence on cell adhesion. Cytotoxicity measurement of prepared blends was conducted to find out whether the prepared materials were non-cytotoxic. The best temperatures for 3D printing were 195/190, 195/175, and 195/165 °C for PHB-soap/PLA-SN, PHB/PCL-SN, and PHB/PCL-SN-TCP, respectively. Their mechanical properties (strengths ~40 MPa, moduli ~2.5 GPa) were comparable with human trabecular bone. The calculated surface energies of all blends were ~40 mN/m. Unfortunately, only two out of three materials were proven to be non-cytotoxic (both PHB/PCL blends).

Calcium phosphate incorporated in silk fibroin/methylcellulose based injectable hydrogel: Preparation, characterization, and in vitro biological evaluation for bone defect treatment.

Bone defect is still a challenging problem in orthopedic practice. Injectable bone substitutes that can fill different geometry of bone defect and improve biological environment for bone regeneration are attracting attention. Herein, silk fibroin (SF) is noticeable polymer regarding its biocompatible and biodegradable properties. Thus, the calcium phosphate particles incorporated in silk fibroin/methylcellulose (CAPs-SF/MC) and only methylcellulose (CAPs-MC) hydrogels are developed and compared their physicochemical properties. Both CAPs-hydrogels solutions can be administered with a low injectability force of ~6 N, and they require ~40-min to change to hydrogel at physiological temperature (37°C). The CAPs are evenly distributed throughout the hydrogel matrix and are capable transformed to bioactive hydroxyapatite at pH 7.4. The CAPs in CAPs-SF/MC have a smaller size than those in CAPs-MC. Moreover, CAPs-SF/MC exhibit gradual degradation, as prediction of the degradation mechanism by the Peppas-Sahlin model and show a greater ability to sustain CAPs release. CAPs-SF/MC has good biocompatibility with less cytotoxicity in a dose-dependent manner on mouse preosteoblast cell line (MC3T3-E1) when compared to CAPs-MC. CAPs-SF/MC hydrogels also have better possibility for promoting cell proliferation and differentiation. In conclusion SF incorporated into composite injectable hydrogel potentially improve biological characteristics and may provide clinical advantages.