A Tunable Calcium Phosphate Coating to Drive in vivo Osseointegration of Composite Engineered Tissues.

Varying degrees of hydroxyapatite (HA) surface functionalization have been implicated as the primary driver of differential osteogenesis observed in infiltrating cells. The ability to reliably create spatially controlled areas of mineralization in composite engineered tissues is of growing interest in the field, and the use of HA-functionalized biomaterials may provide a robust solution to this challenge. In this study, we successfully fabricated polycaprolactone salt-leached scaffolds with two levels of a biomimetic calcium phosphate coating to examine their effects on MSC osteogenesis. Longer duration coating in simulated body fluid (SBF) led to increased HA crystal nucleation within scaffold interiors as well as more robust HA crystal formation on scaffold surfaces. Ultimately, the increased surface stiffness of scaffolds coated in SBF for 7 days in comparison to scaffolds coated in SBF for 1 day led to more robust osteogenesis of MSCs in vitro without the assistance of osteogenic signaling molecules. This study also demonstrated that the use of SBF-based HA coatings can promote higher levels of osteogenesis in vivo. Finally, when incorporated as the endplate region of a larger tissue-engineered intervertebral disc replacement, HA coating did not induce mineralization in or promote cell migration out of neighboring biomaterials. Overall, these results verified tunable biomimetic HA coatings as a promising biomaterial modification to promote discrete regions of mineralization within composite engineered tissues.

Role of halotolerant and chitinolytic bacteria in phytoremediation of saline soil using spinach plant.

Novel technologies are required for rapid reclamation of saline soils. The halotrophic and chitinolytic bacterial strains were used for phytoremediation of saline soils using spinach plants (Spinacia oleracea L.). The previously isolated chitinolytic bacteria showed high antifungal potential against Fusarium oxysporum, and Alternaria spp. The halotolerant bacterial strains were previously isolated showing a salt tolerance of up to 20% in culture media. Specially designed microcosms were used here to investigate the reclamation of saline soil by bacteria. The soil salinity was reduced by both types of bacteria (from 6.5 to 2 dS/m). A decline in Na contents from 22-24 to 9-12 meq/L and in sodium adsorption ratio from 10-11 to 7-8 was also observed in saline soils. The Ca/Mg contents increased from 24 to 30-33 meq/L. The bioassays were performed to evaluate the effect of the bacteria on the phytoremediation. The shoot, root weights (both fresh (1.927 g, 0.244 g) and dry (0.387 g, 0.104 g)) increased by bacterial inoculation as compared to control in saline soils. The Na/K ratio decreased in plant tissues. Here we report the increased efficacy of phytoremediation by combined inoculation of chitinolytic and halotolerant bacterial strains in soil which has never been reported before.

Relationship between soil and groundwater salinity in the Western Canada Sedimentary Basin.

Saturated soil paste extracts indicate soluble ions in soil pore water that are available to vegetation. As such, they are thought to accurately describe the relationship between soil and groundwater salinity. To test this assumption, soil and groundwater samples were collected from 575 monitoring wells in saline regions of the Western Canadian Sedimentary Basin (WCSB). Samples were analyzed for electrical conductivity (EC) and Cl-, Na+, Ca2+, Mg2+, K+, SO42-, and HCO- 3 content. We compared groundwater ionic concentrations to paste extracts derived from matching soils, finding that differences from in situ soil porosity cause saturated pastes to underestimate groundwater salinity. Therefore, we provide pedotransfer functions for accurately calculating groundwater quality from soil data. In addition, we discuss the effects of porosity and soil composition on the saturated paste method, as measured through hydraulic conductivity, saturation percent, and sample lithology. Groundwater salinity may also influence further leaching of salts from soil. As produced water (NaCl brine) spills are common across the sulfate-rich soils of the WCSB, we considered the effects of NaCl on leaching of other ions, finding that influx of Na+ into groundwater is associated with increased sulfate leaching from soil. Therefore, considering the secondary effects of produced water on groundwater quality is essential to spill management.

Acidification with nitric acid improves chemical characteristics and reduces phytotoxicity of alkaline chars.

Charred organic matter is recently receiving attention for its potential use as soilless growth medium. However, depending on its origin and on the manufacturing technology, it can result toxic for plants. This fact implies that a detoxifying treatment ought to be devised in order to reclaim char in this way. We have studied three materials which combine these factors: two pyrolyzed biochars, one from forest waste (BCH-FW) and another from olive mill waste (BCH-OMW), and one hydrothermally carbonized hydrochar from forest waste (HYD-FW). These materials are suspicious of phytotoxicity due to their high pH, high salinity, or presence of organic toxics. For these new materials, it is mandatory to select fast and reliable bioassays to predict their potential phytotoxicity. In order to achieve this goal water extracts of the three chars were subjected to bioassays of seed germination and bioassays of seedling growth in hydroponic conditions. The biochar from olive mill waste and the hydrochar, but not the biochar from forest waste, showed considerable phytotoxicity as seed germination and plant growth were negatively affected (e.g. BCH-OMW reduced seed germination by 80% and caused early seedling death). In order to adjust pH and electrical conductivity for plant growth, treatments of acidification and salt leaching with optimal diluted HNO3 solutions (0.3 N, 0.2 N, and 0.75 N for BCH-OMW, BCH-FW, and HYD-FW, respectively) as calculated from titration curves, were conducted. The acid treatment reduced electrical conductivity in BCH-OMW (from 9.2 to 4.5 dS m-1), pH (maximum in BCH-FW from 9.6 to 6.2) and water soluble carbonaceous compounds (maximum in HYD-FW from 5969 to 2145 mg kg-1) in the three chars, and increased N content (maximum in BCH-OMW from 50 to 6342 mg kg-1) in the three chars. Bioassays on acid-treated chars demonstrated the absence of phytotoxicity and even stimulation of seedling growth over the control (increase of 86% and 56% for BCH-FW and HYD-FW, respectively). We conclude that acidification of chars with diluted HNO3 is a viable technique to conform chars to standards for plant growth purposes.

Evaluating effect of salt leaching method on release and swelling rate of metformin nanoparticles loaded-chitosan/polyvinyl alcohol porous composite.

In this study, salt leaching (SL) technique was used to prepare a chitosan/polyvinyl alcohol (CS/PVA) polymeric composite in order to load metformin nanoparticles (METNPs). Sodium chloride was added to the CS/PVA (0.5:0.1) composite to create a porous hydrogel using the SL technique. METNPs were then prepared by water/oil (w/o) method and loaded into the hydrogel structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed that >80 % of the METNPs were in the range of 10 nm. As a result, encapsulation increased due to the increase in surface-to-volume ratio. Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) results confirmed that creating porosity in the polymer composition by the SL method led to increased CS/PVA polymer chain mobility. The drug encapsulation increased due to more porosity, and the release in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) was according to the controlled diffusion kinetics. Furthermore, the drug release from CS/PVA composite was anomalous carrier type that could be attributed to the addition of salt. However, due to the increase the amount of PVA and the creation of a monotonous composite structure, encapsulation of drug decreased, which is in accordance with the polymer relaxation mechanism.

Fabrication of elliptically constructed liquid crystalline elastomeric scaffolds for 3D artificial tissues.

Inspired by the orientation and the fibrous structure of human muscle tissues, we fabricated preconstructed porous liquid crystalline (LC) scaffolds through a two-step polymerization and salt leaching method. A novel strategy combining the aligning properties of LCs and the ease of processing of elastomers for the preparation of elliptical scaffolds for muscle cell culture was proposed in this research. Different from the other types of scaffolds, our biocompatible LC scaffold that can be implanted into the human body using a supporting unit to improve the mechanical properties compared with those of natural muscle. To evaluate the synthesized scaffolds, in vitro experiments using normal human dermal fibroblast (NHDF) cells and smooth muscle cells from rats were carried out, and the sample cells were cultured on each sample scaffold. Based on the results of long-term culture of NHDF cells on the LC scaffolds, it can be confirmed that all three kinds of LC scaffolds have good biocompatibility and provide enough space for cell growth. The addition of gelatin can significantly enhance the biocompatibility of the synthesized scaffolds. Evaluation of scaffold morphologies on cell growth indicates that the molecular arrangement on the scaffolds can induce the growth direction of smooth muscle cells to a certain extent, thereby increasing the formation of highly ordered arrangement tissues. The population doubling time of NHDF cells on the different scaffolds suggest that gelatin can improve the attachment and growth of cells. Investigation of cell viability on LC scaffolds shows that the original LC scaffolds already possess excellent biocompatibility. Additionally, the average cell viability of smooth muscle cells was above 90%, showing that the LC scaffolds in this research are suitable for application in muscle tissue engineering. Based on the results, the gelatin-coated scaffolds are more conducive to the growth of cells in this research and provide promising candidates for tissue engineering in biomedical fields and research fields.

Design and manufacture of 3D-cylindrical scaffolds based on PLA/TPU/n-HA with the help of dual salt leaching technique suggested for use in cancellous bone tissue engineering.

A series of 3-D scaffolds based on polylactic acid (PLA) and thermoplastic polyurethane (TPU) as major phase and hydroxyapatite nanoparticles (n-HA) were prepared by using the dual leaching technique. Fourier-transform infrared spectroscopy analysis showed that almost the interactions between the constituent materials can be identified based on their functional groups. The results of thermogravimetric analysis were used to obtain the best time to prepare the samples without residual of any progen additives. The scanning electron macroscopy images clearly proved that the dual leaching technique is an effective method to prepare the appropriate morphology and also a very good dispersion and distribution for n-HA can be obtained. Dynamic contact angles showed that the presence of TPU in the PLA matrix has a positive effect on the hydrophilicity of the scaffolds. The bulk modulus (κ) values of S-PLA70TPU30H5 in dry and wet conditions were 321 and 212 Pa, respectively and the compressibility coefficient (ß) of pure samples was higher than that of other scaffolds, while among the nanocomposite samples, the compressibility coefficient of S-PLA70TPU30H5 and S-PLA50TPU50H5 samples in dry and wet conditions was higher than that of other samples. Biological tests such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay, cell adhesion, 4',6-diamidino-2-phenylindole (DAPI) analysis and alizarin red were also performed, and the results obtained for 3D scaffolds were good. In the DAPI analysis test, sample 3D-S-PLA70TPU30H5 showed good behavior, and also in the alizarin red test, the amount of minerals created in 3D-S-PLA50TPU50H5 was significant.

Dual leaching technique was used to prepare cylindrical scaffolds with high porosity.3D cylindrical scaffolds based on PLA/TPU/n-HA were proposed for use in cancellous bone.Bulk modulus and compressibility coefficient of 3D cylindrical scaffolds were obtained in wet and dry conditions.DAPI analysis showed the role of n-HA nanoparticles on cell growth in 3D cylindrical scaffolds.Alizarin red studies showed that sample PLA50TPU50H5 has more calcium content.

Polyhydroxybutyrate (PHB) in nanoparticulate form improves physical and biological performance of scaffolds.

Polyhydroxyalkanoates (PHAs) are natural polyesters produced by microorganisms as a source of intracellular energy reserves. Due to their desirable material characteristics, these polymers have been thoroughly investigated for tissue engineering and drug delivery applications. A tissue engineering scaffold serves as a substitute of the native extracellular matrix (ECM) and plays a crucial role in tissue regeneration by providing temporary support for cells during natural ECM formation. In this study, porous, biodegradable scaffolds were prepared using native polyhydroxybutyrate (PHB) and PHB in nanoparticulate form using salt leaching method, to investigate the differences in the physicochemical properties such as crystallinity, hydrophobicity, surface morphology, roughness, and surface area and biological properties of the prepared scaffolds. As per the BET analysis, PHB nanoparticles-based (PHBN) scaffolds presented a significant difference in the surface area as compare to PHB scaffolds. PHBN scaffolds showed decreased crystallinity and improved mechanical strength as compared to PHB scaffolds. Thermogravimetry analysis shows delayed degradation of PHBN scaffolds. An examination of Vero cell lines' cell viability and adhesion over time revealed enhanced performance of PHBN scaffolds. Our research suggests that scaffold made of PHB nanoparticles could serve as a superior material for tissue engineering applications than its native form.

Fabricated polyhydroxyalkanoates blend scaffolds enhance cell viability and cell proliferation.

For tissue engineering applications, cell adhesion and proliferation are crucial factors, and blending polymers is one of the most effective ways to create a biocompatible scaffold with desired properties. In order to create new potential porous, biodegradable scaffolds using salt leaching technique, poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were blended in different ratios. SEM, BET, FTIR, and water contact angle measurements were used to analyze the scaffolds' porous surface, surface area, and roughness, chemical interaction, and hydrophilicity. Additionally, a hemolysis assay revealed that the mixtures were hemocompatible and had no impact on red blood cells. Different cells- Vero, Hela and MDBK cell lines cultured on the porous mats of these biopolymeric scaffolds exhibited significant increase in cell viability and attachment over time. The overall finding was that blended scaffolds exhibited reduced crystallinity, diverse porosity, higher surface area and hydrophilicity, and better cell viability, proliferation and adhesion. Our findings imply that a blended scaffold could be more suitable for use in tissue engineering applications.

Fabrication and histological evaluation of porous carbonate apatite blocks using disodium hydrogen phosphate crystals as a porogen and phosphatization accelerator.

The porous architecture of artificial bones plays a pivotal role in bone ingrowth. Although salt leaching methods produce predictable porous architectures, their application in the low-temperature fabrication of ceramics remains a challenge. Carbonate apatite (CO3 Ap) blocks with three ranges of pore sizes: 100-200, 200-400, and 400-600 µm, were fabricated from CaCO3 blocks with embedded Na2 HPO4 crystals as a porogen and accelerator for CaCO3 -to-CO3 Ap conversion. CaCO3 blocks were obtained from Ca(OH)2 compacts with Na2 HPO4 by CO2 flow at 100% humidity. When carbonated under 100% water humidity, the dissolution of Na2 HPO4 and the formation of hydroxyapatite were observed. Using 90% methanol and 10% water were beneficial in avoiding the Na2 HPO4 consumption and generating the metastable CaCO3 vaterite, which was rapidly converted into CO3 Ap in a Na2 HPO4 solution in 7 days. For the histological evaluation, the CO3 Ap blocks were implanted in rabbit femur defects. Four weeks after implantation, new bone was formed at the edges of the blocks. After 12 weeks, new bone was observed in the central areas of the material. Notably, CO3 Ap blocks with pore sizes of 100-200 µm were the most effective, exhibiting approximately 23% new bone area. This study sheds new light on the fabrication of tailored porous blocks and provides a useful guide for designing artificial bones.

Fabrication and Testing of Multi-Hierarchical Porous Scaffolds Designed for Bone Regeneration via Additive Manufacturing Processes.

Bone implants or replacements are very scarce due to the low donor availability and the high rate of body rejection. For this reason, tissue engineering strategies have been developed as alternative solutions to this problem. This research sought to create a cellular scaffold with an intricate and complex network of interconnected pores and microchannels using salt leaching and additive manufacturing (3D printing) methods that mimic the hierarchical internal structure of the bone. A biocompatible hydrogel film (based on poly-ethylene glycol) was used to cover the surface of different polymeric scaffolds. This thin film was then exposed to various stimuli to spontaneously form wrinkled micropatterns, with the aim of increasing the contact area and the material's biocompatibility. The main innovation of this study was to include these wrinkled micropatterns on the surface of the scaffold by taking advantage of thin polymer film surface instabilities. On the other hand, salt and nano-hydroxyapatite (nHA) particles were included in the polymeric matrix to create a modified filament for 3D printing. The printed part was leached to eliminate porogen particles, leaving homogenously distributed pores on the structure. The pores have a mean size of 26.4 ± 9.9 µm, resulting in a global scaffold porosity of ~42% (including pores and microchannels). The presence of nHA particles, which display a homogeneous distribution according to the FE-SEM and EDX results, have a slight influence on the mechanical resistance of the material, but incredibly, despite being a bioactive compound for bone cells, did not show a significant increase in cell viability on the scaffold surface. However, the synergistic effect between the presence of the hydrogel and the pores on the material does produce an increase in cell viability compared to the control sample and the bare PCL material.

Design and Testing of a Separation and Desalination Device for Farmland Saline-Alkaline Water in Arid Areas.

To solve the problem of soil salination and to desalinate saline−alkaline water in arid areas, this study involved the design and testing of a separation and desalination device for farmland saline−alkaline water that is suitable for arid areas. The results of this study indicate that after the pretreatment of farmland saline−alkaline water, the water yielded by the pretreatment device had a mean turbidity of <1 and a mean silt density index (SDI) of <3, which met the working conditions of nanofiltration (NF) and reverse osmosis (RO) membranes. When used to filter saline−alkaline water, the composite NF−RO membrane system achieved a desalination rate of 97.06%, a total hardness removal rate of 97.83%, and a Cl− removal rate of 99.65%, which satisfied the standard for irrigation water quality. Some indicators of the yielded water reached the hygienic standard for drinking water, thus successfully reutilizing water resources. The circulating solar collector tube of the device was designed with a collection area of 6 m2, which could basically satisfy the heat demand of the flash tank for distillation. The design of the flash tank and the shell-and-tube circulating condenser met the requirements for vapor condensation. The crystals in the solar salt box precipitated under solar action. X-ray diffraction was used to identify the primary compound of the crystals as NaCl, suggesting that the precipitates have potential value as industrial salts. This study offers new technical references and helpful engineering guidance for arid saline−alkaline enrichment areas facing the problem of saline farmland irrigation water.

Effect of Sodium Carboxymethyl Cellulose on Water and Salt Transport Characteristics of Saline-Alkali Soil in Xinjiang, China.

The scientific use of sodium carboxymethyl cellulose (CMC) to improve the production capacity of saline-alkali soil is critical to achieve green agriculture and sustainable land use. It serves as a foundation for the scientific use of CMC to clarify the water and salt transport characteristics of CMC-treated soil. In this study, a one-dimensional soil column infiltration experiment was carried out to investigate the effects of different CMC dosages (0, 0.2, 0.4, 0.6, and 0.8 g/kg) on the infiltration characteristics, infiltration model parameters, water and salt distribution, and salt leaching of saline-alkali soil in Xinjiang, China. The results showed that the final cumulative infiltration of CMC-treated soil increased by 8.63-20.72%, and the infiltration time to reach the preset wetting front depth increased by 1.02-3.96 times. The sorptivity (S) in the Philip infiltration model and comprehensive shape coefficient (α) in the algebraic infiltration model showed a trend of increasing first and then decreasing with CMC dosage, revealing a quadratic polynomial relationship. The algebraic model could accurately simulate the water content profile of CMC-treated soil. CMC enhanced the soil water holding capacity and salt leaching efficiency. The average soil water content, desalination rate, and leaching efficiency were increased by 5.18-15.54%, 21.17-57.15%, and 11.61-30.18%, respectively. The effect of water retention and salt inhibition on loamy sand was the best when the CMC dosage was 0.6 g/ kg. In conclusion, the results provide a theoretical basis for the rational application of CMC to improve saline-alkali soil in arid areas.

Chondrogenic Differentiation of Human Mesenchymal Stem Cells and Macrophage Polarization on 3D-Printed Poly(ε-caprolactone)/Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Blended Scaffolds with Different Secondary Porous Structures.

This study was aimed to evaluate the chondrogenic differentiation of human mesenchymal stem cells (hMSCs) and polarization of THP-1-derived macrophages cultured on poly(ε-caprolactone) (PC)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PH) blended scaffolds with dual primary (PP) and secondary (SP) pores, which were fabricated via a 3D printing technique, i.e., fused deposition modeling, followed by a salt-leaching process at 50 °C for varied times, i.e., 15, 30, and 60 min. Sodium chloride (SC), a porogen, was initially incorporated in the blend at varied weight percentages, i.e., 0, 25, and 50%, whereas 1 M NaOH solution and deionized water were used as salt-leaching agents. To elucidate the surface properties of the developed scaffolds, directly governed by the amount of the salt originally mixed and the salt-leaching efficiency, several characterization techniques, e.g., scanning electron microscopy, X-ray microcomputed tomography, mercury intrusion porosimetry, atomic force microscopy, and contact angle measurement, were used. Meanwhile, the salt-leaching efficiency was determined by means of weight loss measurement and thermogravimetric analysis. It was found that the alkaline solution could satisfactorily leach out the salt particles in 60 min with a mild etching of the polymer framework. The most immensely and homogeneously pitted filament surface was observed in the NaOH-treated scaffold initially integrated with 50% salt, i.e., 60B_PC/PH/50SC; the SP structure was mostly open and interconnected. The size of most of micropores was about 0.14 µm. With its suitable microsurface roughness and hydrophilicity, 60B_PC/PH/50SC could properly support the initial attachment and lamellipodia formation of hMSCs, which was favorable for chondrogenesis. Consequently, a significantly increased ratio of glycosaminoglycans/deoxyribonucleic acid and a superior expression of the COL2A1 gene were detected when cells were grown on this material. Although 60B_PC/PH/50SC induced the macrophages to secrete a slightly high level of IL-1ß during the first few days of culture, the polarized M1 cells could return to a nearly normal stage at Day7, suggesting no unfavorable chronic inflammation caused by the material.

Combination of Nitric Oxide Release and Surface Texture for Mitigating the Foreign Body Response.

The tissue response to polyurethane (PU)-coated implants employing active and/or passive FBR mitigation techniques was evaluated over a 28 day study in a diabetic swine model. Active FBR mitigation was achieved through the sustained release of nitric oxide (NO) from a mesoporous silica nanoparticle-doped PU coating. Passive FBR mitigation was achieved through the application of a foam- or fiber-based topcoat. These topcoats were designed to possess topographical features known to promote tissue integration with foam-coated implants having pore sizes of approximately 50 µm and fiber-coated implants consisting of fiber diameters of less than 1 µm. Nitric oxide-release profiles were minimally impacted by the presence of either topcoat. Inflammatory cell density and collagen density at the implant-tissue interface were assessed at 7, 14, 21, and 28 days following implantation. Nitric oxide-releasing implants had significantly lower inflammatory cell density and collagen density than non-NO-releasing controls. The presence of a topcoat did not significantly impact inflammatory cell density, though top-coated textured implants resulted in significantly lower collagen density, irrespective of NO release. Overall, coatings that combine NO release with surface texture demonstrated the greatest potential for tissue-based biomedical device applications.

Preparation and Characterization of Porous Scaffolds Based on Poly(3-hydroxybutyrate) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate).

Poly(hydroxyalkanoates) (PHAs) with different material properties, namely, the homopolymer poly(3-hydroxybutyrate), P(3HB), and the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate, P(3HB-co-3HV), with a 3HV of 25 wt.%, were used for the preparation of porous biopolymeric scaffolds. Solvent casting with particulate leaching (SCPL) and emulsion templating were evaluated to process these biopolymers in porous scaffolds. SCPL scaffolds were highly hydrophilic (>170% swelling in water) but fragile, probably due to the increase of the polymer's polydispersity index and its high porosity (>50%). In contrast, the emulsion templating technique resulted in scaffolds with a good compromise between porosity (27-49% porosity) and hydrophilicity (>30% water swelling) and without impairing their mechanical properties (3.18-3.35 MPa tensile strength and 0.07-0.11 MPa Young's Modulus). These specifications are in the same range compared to other polymer-based scaffolds developed for tissue engineering. P(3HB-co-3HV) displayed the best overall properties, namely, lower crystallinity (11.3%) and higher flexibility (14.8% elongation at break. Our findings highlight the potency of our natural biopolyesters for the future development of novel porous scaffolds in tissue engineering, thanks also to their safety and biodegradability.

Comparison of Scaffolds Fabricated via 3D Printing and Salt Leaching: In Vivo Imaging, Biodegradation, and Inflammation.

In this work, we prepared fluorescently labeled poly(ε-caprolactone-ran-lactic acid) (PCLA-F) as a biomaterial to fabricate three-dimensional (3D) scaffolds via salt leaching and 3D printing. The salt-leached PCLA-F scaffold was fabricated using NaCl and methylene chloride, and it had an irregular, interconnected 3D structure. The printed PCLA-F scaffold was fabricated using a fused deposition modeling printer, and it had a layered, orthogonally oriented 3D structure. The printed scaffold fabrication method was clearly more efficient than the salt leaching method in terms of productivity and repeatability. In the in vivo fluorescence imaging of mice and gel permeation chromatography of scaffolds removed from rats, the salt-leached PCLA scaffolds showed slightly faster degradation than the printed PCLA scaffolds. In the inflammation reaction, the printed PCLA scaffolds induced a slightly stronger inflammation reaction due to the slower biodegradation. Collectively, we can conclude that in vivo biodegradability and inflammation of scaffolds were affected by the scaffold fabrication method.

Salt Tolerance and Na Allocation in Sorghum bicolor under Variable Soil and Water Salinity.

Salinity is a major constraint for plant growth in world areas exposed to salinization. Sorghum bicolor (L.) Moench is a species that has received attention for biomass production in saline areas thanks to drought and salinity tolerance. To improve the knowledge in the mechanisms of salt tolerance and sodium allocation to plant organs, a pot experiment was set up. The experimental design combined three levels of soil salinity (0, 3, and 6 dS m-1) with three levels of water salinity (0, 2-4, and 4-8 dS m-1) and two water regimes: no salt leaching (No SL) and salt leaching (SL). This latter regime was carried out with the same three water salinity levels and resulted in average +81% water supply. High soil salinity associated with high water salinity (HSS-HWS) affected plant growth and final dry weight (DW) to a greater extent in No SL (-87% DW) than SL (-42% DW). Additionally, HSS-HWS determined a stronger decrease in leaf water potential and relative water content under No SL than SL. HSS-HWS with No SL resulted in a higher Na bioaccumulation from soil to plant and in translocation from roots to stem and, finally, leaves, which are the most sensitive organ. Higher water availability (SL), although determining higher salt input when associated with HWS, limited Na bioaccumulation, prevented Na translocation to leaves, and enhanced selective absorption of Ca vs. Na. At plant level, higher Na accumulation was associated with lower Ca and Mg accumulation, especially in No SL. This indicates altered ion homeostasis and cation unbalance.

In vitro and in vivo performance of a propolis-coated polyurethane wound dressing with high porosity and antibacterial efficacy.

Wound dressings with antimicrobial and wound healing accelerating properties are emerging as valuable options to prevent wound infection and improve the wound healing process. In this study, high porous polyurethane (PU) foams were successfully prepared using salt leaching/solvent casting method and were coated with propolis as a well-known anti-bacterial agent. The wound dressings were subjected to detail analyzes using electron microscopy, reflectance Fourier transform infrared spectroscopy, mechanical properties, contact angle measurement, ratio swelling, porosity measurement, and in vitro and in vivo evaluations. The prepared wound dressings had high porosity (more than 80%) with homogeneous pore structure and sufficient interconnectivity. The increase of propolis concentration (10%-30%) caused tensile strength decrease (5.26 ± 0.40-2.99 ± 0.11 MPa), elongation at break increase (372 ± 12-434 ± 22%), contact angle decrease (114.52 ± 2.31° to 35.53 ± 1.65°), water absorption decreased (243 ± 15-207 ± 14%) and enhancement of the antibacterial activity against Escherichia coli and Staphylococcus aureus. The propolis coated wound dressing exhibited significant enhancement of in vitro cellular compatibility and in vivo wound healing which had direct relative with coated propolis concentration. Therefore, propolis-coated polyurethane wound dressing can be an appropriate candidate for more pre-clinical investigations.

Mechanical properties of highly porous PEEK bionanocomposites incorporated with carbon and hydroxyapatite nanoparticles for scaffold applications.

Bone regeneration is of great importance worldwide, because of various bone diseases, such as infections, tumors, and resultant fracture, birth defects, and bone loss due to trauma, explosion, or accident. Bone regeneration can be achieved by several materials and templates manufactured through various fabrication techniques. Uses of different materials and scaffold fabrication techniques have been explored over the past 20 years. In this research, polyetheretherketone (PEEK) was used to fabricate highly porous bionanocomposite foams for bone scaffolding. Melt casting and salt porogen (200-500 µm size) leaching methods were adapted to create an adequate pore size and the necessary percent of porosity, because pore size plays a vital role in cell implantation and growth. Porosity (75% and 85%) of the prepared scaffolds was adjusted by changing salt concentrations in the PEEK powder. Hydroxyapatite (HA) and carbon particles were used to improve cell attachments and interactions with the porous PEEK and to increase the mechanical properties of the scaffold materials. Carbon fiber (CF) and carbon nanotubes (CNTs) were uniformly dispersed into the PEEK powder before melt casting to enhance the mechanical properties and to observe the influence of the carbon particles on the properties of PEEK bionanocomposite foam. Compression test results of the fabricated bionanocomposites showed that HA and carbon particles are the potential filler materials for the enhancement of bionanocomposite mechanical properties. About 186% enhancement of compression modulus and 43% enhancement of yield strength were observed while incorporating only 0.5 wt% of CNTs into PEEK/HA bionanocomposites having 75% porosity, compared to PEEK/HA 20 wt% bionanocomposites. Micro-computed tomography (micro-CT) test results reveal that pore size and interconnectivity of the nanocomposite foams are in order and within the designed sizes. Mechanical tests proved that PEEK bionanocomposite foam has the potential for use in bone scaffolding and other biomedical applications.