Hemodynamic monitoring in liver transplantation 'the hemodynamic system'.

PURPOSE OF REVIEW: The purpose of this article is to provide a comprehensive review of hemodynamic monitoring in liver transplantation. RECENT FINDINGS: Radial arterial blood pressure monitoring underestimates the aortic root arterial blood pressure and causes excessive vasopressor and worse outcomes. Brachial and femoral artery monitoring is well tolerated and should be considered in critically ill patients expected to be on high dose pressors. The pulmonary artery catheter is the gold standard of hemodynamic monitoring and is still widely used in liver transplantation; however, it is a highly invasive monitor with potential for serious complications and most of its data can be obtained by other less invasive monitors. Rescue transesophageal echocardiography relies on few simple views and should be available as a standby to manage sudden hemodynamic instability. Risk of esophageal bleeding from transesophageal echocardiography in liver transplantation is the same as in other patient populations. The arterial pulse waveform analysis based cardiac output devices are minimally invasive and have the advantage of real-time beat to beat monitoring of cardiac output. No hemodynamic monitor can improve clinical outcomes unless integrated into a goal-directed hemodynamic therapy. The hemodynamic monitoring technique should be tailored to the patient's medical status, surgical technique, and the anesthesiologist's level of expertise. SUMMARY: The current article provides a review of the current hemodynamic monitoring systems and their integration in goal-directed hemodynamic therapy.

Regeneration of critical-sized grade II furcation using a novel injectable melatonin-loaded scaffold.

BACKGROUND: Periodontal regenerative therapy using bone-substituting materials has gained favorable clinical significance in enhancing osseous regeneration. These materials should be biocompatible, osteogenic, malleable, and biodegradable. This study assessed the periodontal regenerative capacity of a novel biodegradable bioactive hydrogel template of organic-inorganic composite loaded with melatonin. MATERIALS AND METHODS: A melatonin-loaded alginate-chitosan/beta-tricalcium phosphate composite hydrogel was successfully prepared and characterized. Thirty-six critical-sized bilateral class II furcation defects were created in six Mongrel dogs, and were randomly divided and allocated to three cohorts; sham, unloaded composite, and melatonin-loaded. Periodontal regenerative capacity was evaluated via histologic and histomorphometric analysis. RESULTS: Melatonin-treated group showed accelerated bone formation and advanced maturity, with a significant twofold increase in newly formed inter-radicular bone compared with the unloaded composite. The short-term regenerative efficacy was evident 4 weeks postoperatively as a significant increase in cementum length concurrent with reduction of entrapped epithelium. After 8 weeks, the scaffold produced a quality of newly synthesized bone similar to normal compact bone, with potent periodontal ligament attachment. CONCLUSIONS: Melatonin-loaded hydrogel template accelerated formation and enhanced quality of newly formed bone, allowing complete periodontal regeneration. Furthermore, the scaffold prevented overgrowth and entrapment of epithelial cells in furcation defects.

In-Vitro Cytotoxicity Study: Cell Viability and Cell Morphology of Carbon Nanofibrous Scaffold/Hydroxyapatite Nanocomposites.

Electrospun carbon nanofibers (CNFs), which were modified with hydroxyapatite, were fabricated to be used as a substrate for bone cell proliferation. The CNFs were derived from electrospun polyacrylonitrile (PAN) nanofibers after two steps of heat treatment: stabilization and carbonization. Carbon nanofibrous (CNF)/hydroxyapatite (HA) nanocomposites were prepared by two different methods; one of them being modification during electrospinning (CNF-8HA) and the second method being hydrothermal modification after carbonization (CNF-8HA; hydrothermally) to be used as a platform for bone tissue engineering. The biological investigations were performed using in-vitro cell counting, WST cell viability and cell morphology after three and seven days. L929 mouse fibroblasts were found to be more viable on the hydrothermally-modified CNF scaffolds than on the unmodified CNF scaffolds. The biological characterizations of the synthesized CNF/HA nanofibrous composites indicated higher capability of bone regeneration.

Intraoperative anesthetic management of the liver transplant recipient with portopulmonary hypertension.

PURPOSE OF REVIEW: Liver transplantation in patients with portopulmonary hypertension (POPH) is associated with increased perioperative risk. Important recent advances in the management of liver transplantation recipients with POPH are discussed. RECENT FINDINGS: The presence of POPH at the time of liver transplantation should not be a contraindication for liver transplantation, as POPH is common and may be related to volume overload and/or high cardiac output (CO). Available data suggest that patients with mild POPH (25-35 mmHg) can safely undergo liver transplantation surgery. In more severe cases, treatment of POPH with a combination of vasoactive drugs may lead to successful liver transplantation with normalization of POPH. The key to successful intraoperative anesthetic management is maintaining the right ventricular preload and avoiding right ventricular dysfunction. Techniques include diuresis, intraoperative hemodialysis, venovenous bypass, or extracorporeal membrane oxygenation. Apart from the surgical and anesthetic techniques used, factors that contribute to increased pulmonary vascular resistance have to be avoided and the continuation of the vasodilators into the intraoperative and postoperative periods is crucial. SUMMARY: The current article provides a review of the current challenges and advances in the management of liver transplantation recipients with POPH from the anesthetic point of view.

Correlation between Ca Release and Osteoconduction by 3D-Printed Hydroxyapatite-Based Templates.

The application of hydroxyapatite (HA)-based templates is quite often seen in bone tissue engineering since that HA is an osteoconductive bioceramic material, which mimics the inorganic component of mineralized tissues. However, the reported osteoconductivity varies in vitro and in vivo, and the levels of calcium (Ca) release most favorable to osteoconduction have yet to be determined. In this study, HA-based templates were fabricated by melt-extrusion 3D-printing and characterized in order to determine a possible correlation between Ca release and osteoconduction. The HA-based templates were blended with poly(lactide-co-trimethylene carbonate) (PLATMC) at three different HA ratios: 10, 30, and 50%. The printability and physical properties of the HA templates were compared with those of pristine PLATMC. In vitro, osteoconductivity was assessed using seeded human bone marrow-derived mesenchymal stem cells. A mild rate of Ca release was observed for HA10 templates, which exhibited higher mineralized extracellular matrix (ECM) secretion than PLATMC at 14 and 21 days. In contrast, the high rate of Ca release exhibited by HA30 and HA50 templates was associated with reduced osteoconduction and impeded mineralized ECM secretion in vitro. Similar results were observed in vivo. In the calvarial defect model in rabbit, PLATMC and HA10 templates exhibited the highest amount of new bone formation, with obvious contact osteogenesis on their surfaces. In contrast, HA30 and HA50 exhibited distant osteogenesis and reduced amounts of new bone ingrowth. It is concluded that HA-based templates are osteoconductive only at low rates of Ca release.

Genipin versus Ferric Chloride cross-linked unmodified Gum Arabic/Chitosan/nano-Hydroxyapatite nanocomposite hydrogels as potential scaffolds for bone regeneration.

Ferric chloride (FeCl3) and Genipin were utilized as cross-linkers to create two types of nanocomposite hydrogels through physical and covalent cross-linking methods, respectively. The hydrogels were composed of unmodified Gum Arabic (GA), Chitosan (Ch), and natural nano-Hydroxyapatite (nHA) using an acrylic acid solvent. Both the natural nHA and the FeCl3 vs. genipin cross-linked GA/Ch/nHA nano-composite hydrogels were prepared and characterized using various in vitro and in vivo analysis techniques. The use of FeCl3 and genipin cross-linkers resulted in the formation of novel hydrogels with compressive strengths of (15.43-22.20 MPa), which are comparable to those of natural cortical bone. In vivo evaluation was conducted by creating calvarial defects (6 mm) in Sprague-Dawley male rats. The results showed the formation of new, full-thickness bone at the implantation sites in all groups, as evidenced by digital planar tomography and histological staining with Hematoxylin and Eosin stain (H & E). Additionally, the use of genipin as a cross-linker positively affected the hydrogel's hydrophilicity and porosity. These findings justify further investigation into the potential of these nanocomposite hydrogels for bone regeneration applications.

Hydrothermally reinforcing hydroxyaptatite and bioactive glass on carbon nanofiber scafold for bone tissue engineering.

As a bone tissue engineering scaffold, the objective of this study was to design hierarchical bioceramics based on an electrospun composite of carbon nanofibers (CNF) reinforced with hydroxyapatite (HA) and bioactive glasses (BGs) nanoparticles. The performance of the nanofiber as a scaffold for bone tissue engineering was enhanced by reinforcing it with hydroxyapatite and bioactive glass nanoparticles through a hydrothermal process. The influence of HA and BGs on the morphology and biological properties of carbon nanofibers was examined. The prepared materials were evaluated for cytotoxicity in vitro using the water-soluble tetrazolium salt assay (WST-assay) on Osteoblast-like (MG-63) cells, and oste-ocalcin (OCN), alkaline phosphatase (ALP) activity, total calcium, total protein, and tar-trate-resistant acid phosphatase (TRAcP) were measured. The WST-1, OCN, TRAcP, total calcium, total protein, and ALP activity tests demonstrated that scaffolds reinforced with HA and BGs had excellent in vitro biocompatibility (cell viability and proliferation) and were suitable for repairing damaged bone by stimulating bioactivity and biomarkers of bone cell formation.

Novel magnetic iron-nickel/poly(ethersulfone) mixed matrix membranes for oxygen separation potential without applying an external magnetic field.

This work presents novel magnetic mixed matrix poly(ethersulfone) (PES) membranes that combine the advantages of low-cost common PES polymer and low-cost iron-nickel magnetic alloys. Moreover, the presented magnetic mixed matrix PES membranes were fabricated and used without applying an external magnetic field during either the membrane casting or the separating process. The fabricated magnetic membranes were prepared using the phase inversion technique and N-methylpyrrolidone and N,N-Dimethylformamide solvents mixture with volumetric ratio 1:9 and Lithium chloride as an additive. The used iron-nickel magnetic alloys were prepared by a simple chemical reduction method with unique morphologies (Fe10Ni90; starfish-like and Fe20Ni80; necklace-like). The fabricated membranes were characterized using Scanning Electron Microscope (SEM) and Scanning-Transmission Electron Microscope (STEM) imaging, energy dispersive X-ray (EDX), Thermogravimetric (TGA), and X-ray diffraction (XRD). Also, static water contact angle, membrane thickness, surface roughness, membrane porosity, membrane tensile strength as well as Vibrating Sample Magnetometer (VSM) analysis and oxygen transition rate (OTR) were determined. Moreover, the effect of alloy concentration and using Lithium chloride as an additive on the properties of the fabricated blank PES and magnetic mixed matrix PES membranes were studied. The presented novel magnetic mixed matrix PES membranes have high coercivity up to 106 (emu/g) with 3.61 × 10-5 cm3/cm2·s OTR compared to non-oxygen permeable blank PES membranes. The presented novel magnetic mixed matrix PES membranes have good potential in (oxygen) gas separation.

Improved Mechanical Properties and Bioactivity of Silicate Based Bioceramics Reinforced Poly(ether-ether-ketone) Nanocomposites for Prosthetic Dental Implantology.

Polyether-ether-ketone (PEEK) biomaterial has been increasingly employed for orthopedic, trauma, spinal, and dental implants due to its biocompatibility and in vivo stability. However, a lack of bioactivity and binding ability to natural bone tissue has significantly limited PEEK for many challenging dental implant applications. In this work, nanocomposites based on PEEK reinforced with bioactive silicate-based bioceramics (forsterite or bioglass) as nanofillers were prepared using high energy ball milling followed by melt blending and compression molding. The influence of nanofillers type and content (10, 20 and 30 wt.%) on the crystalline structure, morphology, surface roughness, hydrophilicity, microhardness, elastic compression modulus, and flexural strength of the nanocomposites was investigated. The scanning electron microscopy images of the nanocomposites with low nanofillers content showed a homogenous surface with uniform dispersion within the PEEK matrix with no agglomerates. All nanocomposites showed an increased surface roughness compared to pristine PEEK. It was found that the incorporation of 20 wt.% forsterite was the most effective in the nanocomposite formulation compared with bioglass-based nanocomposites; it has significantly improved the elastic modulus, flexural strength, and microhardness. In vitro bioactivity evaluation, which used biomimetic simulated body fluid indicated the ability of PEEK nanocomposites loaded with forsterite or bioglass nanofillers to precipitate calcium and phosphate bone minerals on its surface. These nanocomposites are expected to be used in long-term load-bearing implant applications and could be recommended as a promising alternative to titanium and zirconia when used as a dental implant material.

Unmodified Gum Arabic/Chitosan/Nanohydroxyapatite Nanocomposite Hydrogels as Potential Scaffolds for Bone Regeneration.

In this work, physical cross-linking was used to create nanocomposite hydrogels composed of unmodified gum arabic (GA), chitosan (Ch), and natural nanohydroxyapatite (nHA), using an acrylic acid (AA) solvent. Different GA/chitosan contents (15%, 25%, and 35% of the used AA) as well as different nHA contents (2, 5, and 10 wt.%), were used and studied. The natural nHA and the fabricated GA/Ch/nHA nanocomposite hydrogels were characterized using different analysis techniques. Using acrylic acid solvent produced novel hydrogels with compressive strength of 15.43-22.20 MPa which is similar to that of natural cortical bone. The addition of natural nHA to the hydrogels resulted in a significant improvement in the compressive strength of the fabricated hydrogels. In vitro studies of water absorption and degradation-and in vivo studies-confirmed that the nanocomposite hydrogels described here are biodegradable, biocompatible, and facilitate apatite formation while immersed in the simulated body fluid (SBF). In light of these findings, the GA/Ch/nHA nanocomposite hydrogels are recommended for preparing bioactive nanoscaffolds for testing in bone regeneration applications.

Novel Magnetic Mixed Cellulose Acetate Matrix Membranes with Oxygen-Enrichment Potential.

This work presents novel magnetic mixed cellulose-based matrix membranes that combine the advantages of a low-cost common polymer matrix, such as cellulose acetate (CA), and a low-cost magnetic filler. Moreover, the presented magnetic mixed CA matrix membranes were fabricated and used without applying an external magnetic field during either the membrane casting or the separating process. Poly(methylmethacrylate) and lithium chloride were used in order to improve the mechanical properties and porosity of the fabricated membranes. The iron-nickel magnetic alloys used were prepared through a simple chemical reduction method with unique morphologies (Fe10Ni90-starfish-like and Fe20Ni80-necklace-like). The novel magnetic mixed CA matrix membranes fabricated were characterized using different analysis techniques, including SEM, EDX, XRD, TGA, and FTIR-ATR analyses. Furthermore, the static water contact angle, membrane thickness, surface roughness, tensile strength, and membrane porosity (using ethanol and water) were determined. In addition, vibrating sample magnetometer (VSM) analysis was conducted and the oxygen transition rate (OTR) was studied. The magnetic mixed CA matrix membrane containing starfish-like Fe10Ni90 alloy was characterized by high coercivity (109 Oe) and an efficient 1.271 × 10-5 cm3/(m2·s) OTR compared to the blank CA membrane with 19.8 Oe coercivity and no OTR. The effects of the polymeric matrix composition, viscosity, and compatibility with the alloys/fillers used on the structure and performance of the fabricated mixed CA matrix membranes compared to the previously used poly(ethersufone) polymeric matrix are discussed and highlighted. The novel magnetic mixed CA matrix membranes presented have good potential for use in the oxygen-enrichment process.

Contact osteogenesis by biodegradable 3D-printed poly(lactide-co-trimethylene carbonate).

BACKGROUND: To support bone regeneration, 3D-printed templates function as temporary guides. The preferred materials are synthetic polymers, due to their ease of processing and biological inertness. Poly(lactide-co-trimethylene carbonate) (PLATMC) has good biological compatibility and currently used in soft tissue regeneration. The aim of this study was to evaluate the osteoconductivity of 3D-printed PLATMC templates for bone tissue engineering, in comparison with the widely used 3D-printed polycaprolactone (PCL) templates. METHODS: The printability and physical properties of 3D-printed templates were assessed, including wettability, tensile properties and the degradation profile. Human bone marrow-derived mesenchymal stem cells (hBMSCs) were used to evaluate osteoconductivity and extracellular matrix secretion in vitro. In addition, 3D-printed templates were implanted in subcutaneous and calvarial bone defect models in rabbits. RESULTS: Compared to PCL, PLATMC exhibited greater wettability, strength, degradation, and promoted osteogenic differentiation of hBMSCs, with superior osteoconductivity. However, the higher ALP activity disclosed by PCL group at 7 and 21 days did not dictate better osteoconductivity. This was confirmed in vivo in the calvarial defect model, where PCL disclosed distant osteogenesis, while PLATMC disclosed greater areas of new bone and obvious contact osteogenesis on surface. CONCLUSIONS: This study shows for the first time the contact osteogenesis formed on a degradable synthetic co-polymer. 3D-printed PLATMC templates disclosed unique contact osteogenesis and significant higher amount of new bone regeneration, thus could be used to advantage in bone tissue engineering.

Preparation and Characterization of a Novel Poly(vinylidene fluoride-co-hexafluoropropylene)/Poly(ethersulfone) Blend Membrane Fabricated Using an Innovative Method of Mixing Electrospinning and Phase Inversion.

In this work, a novel polymeric membrane was innovated in terms of composition and preparation techniques. A blend of poly(vinylidene fluoride-co-hexafluoropropylene) (PcH) and poly(ethersulfone) (PES) (18 wt.% total polymer concentration) was prepared using a N-methylpyrrolidone (NMP) and N, N-Dimethylformamide (DMF) solvents mixture, while Lithium chloride (0.05-0.5 wt.%) was used as an additive. The electrospinning and phase inversion techniques were used together to obtain a novel membrane structure. The prepared membranes were characterized using scanning electron microscope imaging, energy dispersive X-Ray, differential scanning calorimeter, thermogravimetric analysis, and Fourier transfer infrared spectroscopy-attenuated total reflectance analyses. Moreover, the static water contact angle, membrane thickness, porosity, surface roughness as well as water vapor permeability were determined. ImageJ software was used to estimate the average fiber diameter. Additionally, the effect of the change of PcH concentration and coagulation bath temperature on the properties of the fabricated membrane was studied. The novel developed membrane has shown a good efficiency in terms of properties and features, as a membrane suitable for membrane distillation (MD); a high porosity (84.4% ± 0.6), hydrophobic surface (136.39° ± 3.1 static water contact angle), and a water vapor permeability of around 4.37 × 10-5 g·m/m2·day·Pa were obtained. The prepared membrane can be compared to the MD membranes commercially available in terms of properties and economic value.

Iron-Nickel Alloy with Starfish-like Shape and Its Unique Magnetic Properties: Effect of Reaction Volume and Metal Concentration on the Synthesized Alloy.

Iron-nickel alloy is an example of bimetallic nanostructures magnetic alloy, which receives intensive and significant attention in recent years due to its desirable superior ferromagnetic and mechanical characteristics. In this work, a unique starfish-like shape of an iron-nickel alloy with unique magnetic properties was presented using a simple, effective, high purity, and low-cost chemical reduction. There is no report on the synthesis of such novel shape without complex precursors and/or surfactants that increase production costs and introduce impurities, so far. The synthesis of five magnetic iron-nickel alloys with varying iron to nickel molar ratios (10-50% Fe) was undertaken by simultaneously reducing Fe(II) and Ni(II) solution using hydrazine hydrate as a reducing agent in strong alkaline media for 15 min at 95-98 °C. The effect of reaction volume and total metal concentration on the properties of the synthesized alloys was studied. Alloy morphology, chemical composition, crystal structure, thermal stability, and magnetic properties of synthesized iron-nickel alloys were characterized by means of SEM, TEM, EDX, XRD, DSC and VSM. ImageJ software was used to calculate the size of the synthesized alloys. A deviation from Vegard's law was recorded for iron molar ration higher than 30%., in which superstructure phase of FeNi3 was formed and the presence of defects in it, as well as the dimensional effects of nanocrystals. The saturation magnetization (Ms), coercivity (Hc), retentivity (Mr), and squareness are strongly affected by the molar ratio of iron and nickel and reaction volume as well as the total metal concentration.

Surface Morphology and Mechanical Properties of Polyether Ether Ketone (PEEK) Nanocomposites Reinforced by Nano-Sized Silica (SiO2) for Prosthodontics and Restorative Dentistry.

In the field of orthopedics and traumatology, polyether ether ketone (PEEK) serves a significant role as a suitable alternative to traditional metal-based implants like titanium. PEEK is being used more commonly to replace traditional dental products. For bonding with various adhesive agents and preserved teeth, the surface alteration of PEEK was investigated. The aim of this research was to understand how different types and contents of nano-sized silica (SiO2) fillers influenced the surface and mechanical properties of PEEK nanocomposites used in prosthodontics. In this work, PEEK based nanocomposites containing hydrophilic or hydrophobic nano-silica were prepared by a compression molding technique. The influence of nano-SiO2 type and content (10, 20 and 30% wt) on surface properties of the resultant nanocomposites was investigated by the use of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), surface roughness analysis, and contact angle measurement. The crystalline structures of PEEK/SiO2 nanocomposites were examined by X-ray diffraction (XRD) spectroscopy. Mechanical properties were measured by microhardness, elastic compression modulus, and flexural strength. All nanocomposites showed increased surface roughness compared to pure PEEK. SEM images revealed that nanocomposites filled with low content hydrophobic nano-SiO2 showed uniform dispersion within the PEEK matrix. The introduction of 10 wt% of hydrophobic nano-SiO2 to the PEEK matrix improved elastic modulus, flexural strength, and microhardness, according to the findings. The addition of nano-SiO2 fillers in a higher weight percentage, over 10%, significantly damages the mechanical characteristics of the resultant nanocomposite. On the basis of the obtained results, PEEK/SiO2 nanocomposites loaded with low content hydrophobic nano-SiO2 are recommended as promising candidates for orthopedic and prosthodontics materials.

Local treatment of experimental mandibular osteomyelitis with an injectable biomimetic gentamicin hydrogel using a new rabbit model.

Mandibular osteomyelitis (OM) is a challenging disease. Our objective was to assess a new OM model in rabbits induced by arsenic trioxide and to assess the efficacy of local treatment of OM using injectable gentamicin-collagen hydrogels (GNT-COLL). OM was induced unilaterally by controlled confinement of arsenic trioxide paste to the root canal of lower incisors of rabbits, while OM progression was characterized for 16 weeks. On the other hand, two injectable COLL hydrogels functionalized with GNT were prepared and characterized for physicochemical properties; a simple GNT-COLL and a nanohydroxyapatite (nHA)- loaded hydrogel (GNT-COLL/nHA). The two hydrogels were evaluated to treat OM model, while a multidose intramuscular GNT solution served as positive control. Outcomes were assessed by standard methods at 4 and 12 weeks post-surgery. The clinical, radiographical, and histopathological findings provided evidence for the validity of the arsenic-induced OM. The results demonstrated that a single intra-lesional injection of the two hydrogels was more suppressive to OM compared to multidose systemic GNT. The composite GNT-COLL/nHA hydrogel proved to induce early preservation of alveolar bone (ridge) length and higher amount of bone area\total area at 4 weeks (40.53% ± 2.34) followed by GNT-COLL (32.21% ± 0.72). On the other hand, the positive control group revealed the least ridge length and bone area\total area (26.22% ± 1.32) at 4 weeks. Both hydrogels successfully arrested OM with no signs of recurrence for up to 12 weeks. Therefore, results support the greater advantages of the composite hydrogel as an osteogenic/antibiotic delivery system in OM treatment.

Viscoelasticity, Mechanical Properties, and In Vitro Bioactivity of Gelatin/Borosilicate Bioactive Glass Nanocomposite Hydrogels as Potential Scaffolds for Bone Regeneration.

Chemical cross-linking was used to create nanocomposite hydrogels made up of gelatin (G) and borosilicate bioactive glass (BBG) with different content (0, 3, and 5 wt.%). The G/BBG nanocomposite hydrogels were studied for their morphology, mechanical properties, and viscoelasticity. SEM images revealed a macroporous interconnected structure with particles scattered across the pore walls. Studies of water absorption and degradation confirmed that the nanocomposite scaffolds were hydrophilic and biodegradable. The addition of 5% BBG to the scaffold formulations increased the compressive modulus by 413% and the compressive intensity by 20%, respectively. At all frequency ranges tested, the storage modulus (G') was greater than the loss modulus (G″), revealing a self-standing elastic nanocomposite hydrogel. The nanocomposite scaffolds facilitated apatite formation while immersed in simulated body fluid (SBF). According to the findings, G/BBG nanocomposite scaffolds could be a promising biomaterial for bone regeneration.

Comparison between a Conventional Anti-Biofouling Compound and a Novel Modified Low-Fouling Polyethersulfone Ultrafiltration Membrane: Bacterial Anti-Attachment, Water Quality and Productivity.

In this work, the efficiency of a conventional chlorination pretreatment is compared with a novel modified low-fouling polyethersulfone (PES) ultrafiltration (UF) membrane, in terms of bacteria attachment and membrane biofouling reduction. This study highlights the use of membrane modification as an effective strategy to reduce bacterial attachment, which is the initial step of biofilm formation, rather than using antimicrobial agents that can enhance bacterial regrowth. The obtained results revealed that the filtration of pretreated, inoculated seawater using the modified PES UF membrane without the pre-chlorination step maintained the highest initial flux (3.27 ± 0.13 m3·m-2·h-1) in the membrane, as well as having one and a half times higher water productivity than the unmodified membrane. The highest removal of bacterial cells was achieved by the modified membrane without chlorination, in which about 12.07 × 104 and 8.9 × 104 colony-forming unit (CFU) m-2 bacterial cells were retained on the unmodified and modified membrane surfaces, respectively, while 29.4 × 106 and 0.42 × 106 CFU mL-1 reached the filtrate for the unmodified and modified membranes, respectively. The use of chlorine disinfectant resulted in significant bacterial regrowth.

Novel Blend for Producing Porous Chitosan-Based Films Suitable for Biomedical Applications.

In this work, a chitosan-gelatin-ferulic acid blend was used in different ratios for preparing novel films that can be used in biomedical applications. Both acetic and formic acid were tested as solvents for the chitosan-gelatin-ferulic acid blend. Glycerol was tested as a plasticizer. The thickness, mechanical strength, static water contact angle and water uptake of the prepared films were determined. Also, the prepared films were characterized using different analysis techniques such as Fourier transform infrared spectroscopy (FT-IR) analysis, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Acetic acid produced continuous compact surfaces that are not recommended for testing in biomedical applications. The plasticized chitosan-gelatin-ferulic acid blend, using formic acid solvent, produced novel hexagonal porous films with a pore size of around 10-14 µm. This blend is recommended for preparing films (scaffolds) for testing in biomedical applications as it has the advantage of a decreased thickness.

Preparation and characterization of carbon nanofibrous/hydroxyapatite sheets for bone tissue engineering.

Critical size bone defects are orthopedic defects that will not heal without intervention or that will not completely heal over the natural life time of the animal. Although bone generally has the ability to regenerate completely however, critical defects require some sort of scaffold to do so. In the current study we proposed a method to obtain a carbon nanofibrous/Hydroxyapatite (HA) bioactive scaffold. The carbon nanofibrous (CNF) nonwoven fabrics were obtained by the use of the electrospinning process of the polymeric solution of poly acrylonitrile "PAN" and subsequent stabilization and carbonization processes. The CNFs sheets were functionalized by both hydroxyapatite (HA) and bovine serum albumin (BSA). The HA was added to the electrospun solution, but in case of (BSA), it was adsorbed after the carbonization process. The changes in the properties taking place in the precursor sheets were investigated using the characterization methods (SEM, FT-IR, TGA and EDX). The prepared materials were tested for biocompatibility via subcutaneous implantation in New Zealand white rabbits. We successfully prepared biocompatible functionalized sheets, which have been modified with HA or HA and BSA. The sheets that were functionalized by both HA and BSA are more biocompatible with fewer inflammatory cells of (neutrophils and lymphocytes) than ones with only HA over the period of 3weeks.