In this study, novel porous cytocompatible scaffolds with a 3D nanocomposite structure were synthesized by using nanoclay particles embedded into a biopolymer blend composed of polyvinyl alcohol (PVA) and chitosan (CS). According to the results, the Fourier transform infrared spectrum confirmed the presence of nanoclay, PVA and CS in the scaffold structure. X-ray diffraction outcomes showed the enhancement of crystalline zone in the synthesized 3D scaffolds by increasing the nanoclay content. Scanning electron microscopy (SEM) images revealed the highly porous interconnected microstructure of the scaffolds. Also, the energy-dispersive X-ray spectra verified the presence of nanoclay, PVA and CS in the sample with the highest nanoclay content. According to mechanical properties and porosity of the synthesized 3D scaffolds, compressive strength (i.e., 3.5 ± 0.2 MPa), elastic modulus (1.42 ± 0.02 GPa) and porosity (75-82%) of the sample with the highest nanoclay content was in the range of mechanical properties and porosity of a natural trabecular bone tissue. The swelling of samples in a phosphate-buffered saline solution was less than the swelling in water. In addition, increasing the content of nanoclay decreases the percentage of swelling. Outcomes of cell culture experiments confirmed that the synthesized 3D scaffolds were not toxic and the cell attachment SEM images showed a sufficient attachment of the cell to the interconnected porous structure of the sample. Results suggest that the synthesized 3D scaffold in this study possesses proper microstructure properties and no cytotoxicity to be replaced with natural bone tissues.
Porous calcium phosphates have osteoconductive properties. The aim of this study was to obtain synthetic calcium phosphate bone graft substitute. X-ray diffraction was employed to investigate the formation of the beta-tricalcium phosphate (β-TCP) phase. We evaluated the effects of bone marrow on the osteoconductivity and mechanical properties of synthetic bone graft (SG). SG cylinders loaded with bone marrow (SGBM) and SG alone were implanted into rabbits femoral condyle bone defects. Histological examinations revealed the resorption of the SG, trabecular bone with osteoblasts and osteoid substance around the implants, and colonization inside the porous β-TCP by newly formed bone. Histomorphometry conducted after three months revealed the osteoid surface to be higher in SGBM than SG (p < 0.05). The compressive strengths of SG and SGBM were significantly higher than the anatomic control at all time periods. The elastic modulus of SBG and SGBM became weaker after implantation. The present results indicate that β-TCP is a good matrix for bone marrow, which contributes osteoinductive properties in an orthotopic. The composite biomaterial may be useful in reconstructive bone surgery. © KSBB
Objective. Brain computer interfaces (BCIs) are slowly making their appearance on the consumer market, accompanied by a higher popularity among the general public. This new group of users requires easy-to-use headsets with robustness to non-precise placement. In this paper, an optimized fixed montage EEG headset for VEP BCIs is proposed. Approach. The proposed layout covers only the most relevant area with large sensors to account for slight misplacement. To obtain large sensors, without having them physically available, we tie multiple sensors together and simulate the effect by averaging the signal of multiple sensors. Main results. In simulations based on recorded 256-channel EEG data, it is shown that a circular center-surround configuration with sensor tying, leading to only eight channels covering a large part of the occipital lobe, can provide high performance and good robustness to misplacement. Automatically optimized layouts were unable to achieve better performance, demonstrating the utility of this manual design. Finally, the performance and benefits of sensor tying in the manual design are then validated in a physical experiment. Significance. The resulting proposed layout fulfills most requirements of an easy to use consumer EEG headset.
To improve anti thrombogenicity of polycaprolactone, nanofibrous mat of this synthetic polymer is prepared by electrospinning method. Subsequently, plain electrospun nanofibrous polycaprolactone was treated by RF oxygen plasma to initiate the graft copolymerization with acrylamide monomers. The surface morphology and average fiber diameter of plain electrospun nanofibrous polycaprolactone were determined by scanning electron microscopy technique. The chemical composition and surface characteristics of the samples were examined by static contact angle measurements, and attenuated total reflectance Fourier transfer infrared (ATR-FTIR) spectroscopy. Atomic force microscopy was employed to investigate the effect of plasma treatment and graft copolymerization on the surface roughness and topography of the samples. Mechanical properties were measured from the stress–strain curve. The amount of platelet adhesion was observed by scanning electron microscopy images. Results indicate that the polycaprolactone synthetic polymer was successfully electrospun with a nanofibrous micro structure. The ATR-FTIR spectrum confirmed the influence of RF oxygen plasma treatment and graft copolymerization. Contact angle outcomes exhibited a massive improvement in the hydrophilic property of the polycaprolactone-plasma-acrylamide sample, and the surface roughness of this sample also decreased dramatically as atomic force microscopy results showed. The mechanical property of the polycaprolactone-plasma-acrylamide sample shows a negligible reduction in comparison with plain electrospun polycaprolactone. The polycaprolactone-plasma-acrylamide sample possesses proper values of mechanical properties compared to natural blood vessels. The SEM images of polycaprolactone, polycaprolactone-plasma, and polycaprolactone-plasma-acrylamide revealed no adhesion of natural platelets for polycaprolactone-plasma-acrylamide. Thus, the polycaprolactone-plasma-acrylamide vascular prosthesis is fabricated and post processed with sufficient surface properties and anti thrombogenicity.
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