Papers by Keyword: Macroporous

Abstract: Bioactive glass and glass-ceramics have a huge interest in biomedical application due to their high biocompatibility and bioactive property. In this study, macro porous glass-ceramic based on 51.26% SiO₂ - 36.56% CaO - 11.83% P₂O₅ and 42.11% SiO₂ - 18.42% CaO - 29.82% Na₂O - 9.65% P₂O₅ (in mol%) were prepared via sol-gel synthesis and powder sintering method. Sodium nitrate was used as the precursor for sodium oxide (Na₂O) composition in the sol-gel glass. Effect of sodium nitrate addition on the sintered glass (glass-ceramic) properties were studied. The stabilized gel-glasses obtained were compacted into pellets and sintered at 1000 °C for 3 hours. It was found that, Na-contained glass-ceramic (Na-GC) crystallized at 71.5% due to increase in sodium-related crystalline phases. Na-GC showed 72.98% of apparent porosity and densified at 27.02% with macro porous structure with pore sizes in the range of 22.4 μm to 302 μm. The macro porous structure of Na-GC was obtained due to the foaming effect occurred during sintering. Flux effect occurred during sintering also resulted in relatively high compressive strength of Na-GC at 21.53 MPa. The macro porous Na-GC also proved to be bioactive as apatite-like structures were deposited on its surface after immersed into SBF solution for 14 days. The prepared macro porous Na-GC has high potential to be used as a scaffold material in biomedical application due to combination of suitable macro-pore size range, bioactive and has sufficient mechanical strength.

Abstract: The macroporous resin is one kind of new non-ionic organic high polymer absorbent with nearly 20 years development. It takes the styrene and the acrylic ester as the monomer, divinyl benzene as the crosslinking agent, the toluene and the xylene as aperture reagents. They intersectantly linked the polymerization to form the porous skeleton structure mutually. This experiment is the utilization of aerosol polymerization method in preparation of rhenium concerned polymeric adsorbent. On research of monomer and crosslinking agent allocated proportion, dispersing agent amount used, temperature and mixing speed control, the different monomer and the crosslinking agent separately affected the synthesis different macroporous polymeric adsorbent. Also we investigated the adsorption performance quality of the different macroporous polymeric adsorbent in order to make the best particle size.

Abstract: In this paper, a new kind of nano-silica embedded cryogel was prepared by solution crosslinking isobutylene-isoprene rubber with silica in benzene at various temperatures. The characteristics of cryogels were manifested by SEM. Sorption tests showed that the cryogels were efficient at removing kinds of oil, aromatic compound and alkane. The results suggested that the maximum sorption capacity was 15.44 g.g^-1 for crude oil, 15.62 g.g^-1 for diesel and 13.16 g.g^-1 for lubricating oil, respectively. Moreover, the cryogels were reusable once they were centrifuged, leading to continuous sorption capacity for these oils. Therefore, the cryogel might be a promising removal material which can be used in large-scale oil or toxic organic liquids spills.

Abstract: Many techniques are used to assess biomaterials implants, always intending to measure osseointegration success and tissue response facing the implanted material. Calcium phosphates are widely used as biomaterial and a major component of bone. Many processing methods have been used to achieve porous materials to allow bone ingrowth with an osteoconductive scaffold for bone. To obtain the macroporous BCP implant it was processed by direct consolidation using the protein-action technique, a globular protein based consolidation with ovalbumin. The samples were sintered at 1250°C for 30 minutes, after sintering samples were cut in 4mm diameter cylinders, with 73% volume of porosity and mean pore size ranging about 100 µm. In the present work the macroporous BCP of HAp:β-TCP is assessed after bone implantation in rabbits tibia by lectinhistochemistry (LHC) technique. Lectins are proteins from non-imune origin which binds with strong specificity carbohydrates, LHC is a technique which mark histologically carbohydrates present in glycoproteins of cells. The macroporous BCP cylindrical samples were implanted in male rabbits tibia to the evaluation of biocompatibility and osseointegration in a period of 2 weeks to 4 weeks. After euthanasia of rabbits, tibia samples from the surgery site were taken and fixed with formalin, decalcified, dehydrated and embedded with paraffin to perform histological slides for both morphological and molecular evaluation. The morphological evaluation were performed on histological slides stained with Haematoxilin and Eosin (HE), while for molecular evaluation LHC was performed on histological slides using the lectins PNA, UEA-1, WGA, sWGA and RCA-1 (Vector Labs). All samples osseointegrated well with the bone and the neoformed bone surrounding the implant took the shape of its surface. The implants also allowed bone ingrowth inside the pores towards the center of implant, characterized by islets of round bone present in the HE stained slides.

Abstract: The development of CaP ceramics involved a better control of the process of resorption and bone substitution. Micro Macroporous Biphasic CaP, (MBCP+) is a concept based on an optimum balance of the more stable phase of HA and more soluble TCP. The material is soluble and gradually dissolves in the body, seeding new bone formation as it releases Ca and P ions into the biological medium. The MBCP+ is selected for tissue engineering in a large European research program on osteoinduction and mesenchymal stem cell technology (REBORNE 7^th EU frame work program, Regenerative Bone defects using New biomedical Engineering approaches, www.reborne.org). We have optimized the matrices in terms of their physical, chemical, and crystal properties, to improve cell colonization and to increase kinetic bone ingrowth. The fast cell colonization and resorption of the material are associated to the interconnected macropores structure which enhances the resorption bone substitution process. The micropore content involves biological fluid diffusion and suitable adsorption surfaces for circulating growth factors. The bioceramics developed for this project was fully characterized using X-Ray diffraction, FTIR, X-rays micro tomography, Hg porosimetry, BET specific surface area, compressive mechanical test, and SEM. Preclinical tests on the optimized scaffold were realized in critical size defects in several sites of implantation and animals (rats, rabbits, goats, dogs).The smart scaffold has a total porosity of 73%, constituted of macropores (>100µm), mesopores of 10 to 100µm and high micropores (<10µm) content of more or less 40%. The crystal size is <0.5 to 1 µm and the specific surface area was around 6m²/g. The in vivo experiment indicated higher colonization by osteogenic cells demonstrating suitable matrices for tissue engineering. The HA/TCP ratio of 20/80 was also more efficient for combination with total bone marrow or stem cell cultivation and expansion before to be implanted.

Abstract: Titanium and its alloys are widely used as biomaterials and interact well with bone tissue. In order, to evaluate more than just morphological osseointegration by histological slides the work aimed to approach a molecular evaluation of bone-implant using lectinhistochemistry (LHC), which binds with high specificity carbohydrates (sugar residues) presents in membrane glycoproteins with the use of lectins. The implanted samples were obtained by powder metallurgy, Ti-13Nb-13Zr alloy with and without gelatin. Pores were achieved by adding gellatin 5 wt% to the hydrogenated metallic powder, after near net shape processing, the samples were thermal treated in vacuum (300 °C/90min) and sintered in high-vacuum (1150 °C/14h). The samples were characterized for porosity (~30%), and subsequently were implanted in rat’s femur bone. After 4 weeks of healing process, bone with implant were sampled to perform LHC in paraffin embedded tissue in histological slides using the lectins PNA, UEA-1, WGA, sWGA and RCA-1. All samples osseointegrated well with the bone, no fibrous capsule was present in the bone which was in contact with the implant. With the molecular approach of osseointegration, adjustments in the processing and structure of macroporous titanium based implants can be performed to achieve friendly structure.

Abstract: Adopting domestic polytetrafluoroethylene (PTFE) turning plate as materials, a new isosceles triangle macroporous mesh was designed. The correspond mould and the special fixtures for continuous punching of ultra-thin plastic sheet were successfully developed. The PTFE mesh was manufactured through computer numerically controlled (CNC) punch. In terms of electronic universal testing machines and microcomputer differential thermal balance, mechanical properties and thermostability of the PTFE mesh were studied. The results indicated that the tensile strength of PTFE mesh is 11.98 MPa which is greater than the literature value of 7.77 MPa, and its heat-resisting performance is excellent without decomposition prior to 312 oC.

Abstract: The ordered colloidal crystals were prepared by sedimentation of a solution of silica colloidal spheres of 298nm. Colloidal crystals were obtained after evaporation at 50°Cfor eight days while solution evaporates. These colloidal crystals were used to be templates and MMA was filled in the gap of silica spheres. SiO2/PMMA structures with a overlayer of PMMA were obtained by polymerization reaction carried out at 80°C for 24 h. After etched with the hydrofluoric acid (HF) for 24h, a piece of bluish violet film can be obtained. The film is flexible and free-standing and is enough tough to be curled to various shape. This kind of film can extend the usage of macroporous structures and have various potential applications in flexible photoelectronic device.

Abstract: The Macroporous Nanocrystalline TiO₂ Thin Film Was Prepared by Dipping-Coating Method. Polystyrene (PS) Microspheres Template Was Used as Pore-Forming Assistant and TiO₂ Sol Was Used as Precursor. the Photoelectric Characteristics of the Samples Were Studied Using Surface Photovoltage (SPV) and Photoacoustic (PA) Techniques. the Presence of a Small Amount of Residual Template Damages the Integrity of the Porous TiO₂ Film with Inverse Opal Structure, and TiO₂ May Be Restricted in Certain Application Fields as Photonic Crystals. a Small Amount of Residual Template Changes the Surface Photovoltaic Properties of the Porous TiO₂ Film, Resulting Mainly in the Broadened Scope and the Increased Intensity of SPV Response.

Abstract: Studies of titanium and its alloys commonly used as biomaterials aim to improve bone-implant interface related problems, which may determine the quality, bone repairing time and therefore the implant clinical success. The goal of this study was to evaluate, in rats, osseointegration of macroporous implants produced by powder metallurgy (PM) method with controlled addition of gelatin. As control group, samples of commercially pure titanium (cpTi) and Ti-13Nb-13Zr alloy obtained by the PM process were used. To obtaining the porous samples, at most 15% in weight of gelatin was added to metallic powders, the samples were thermally treated in vacuum furnace, and sintered at 1150°C. The osseointegration evaluation was performed in Wistar rats, males, for a 28 days period. The morphological analyses, optical microscopy and scanning electron microscopy (SEM), evaluated qualitatively the osseointegration. The PM process modified by addition of gelatin provides with success the obtaining of porous metallic implants. Pore size obtained by this technique allowed the necessary nourishing to cell survival, proving that pores and channels form a high interconnectable network represented by the osseointegration and osteoconduction feature of the porous alloy.