In this research, hWJ-MSCs were grown on silk scaffolds and induced towards chondrogenesis by supplementation with L-ascorbic acid (LAA) or platelet rich plasma (PRP). Silk scaffolds were fabricated ...with salt leaching method by mixing silk fibroin (SF) with silk spidroin (SS). The silk fibroin was obtained from Bombyx mori cocoon that had been degummed, and the silk spidroin was obtained from wild-type spider Argiope appensa. The effect of scaffold composition and inducer on cell proliferation was observed through MTT assay. The most optimal treatment then continued to be used to induce hWJ-MSC towards chondrogenic differentiation for 7 and 21 days. Scaffolds characterization showed that the scaffolds produced had 3D structure with interconnected pores, and all were biocompatible with hWJ-MSCs. Scaffold with the addition of 10% SS + 90% SF showed higher compressive strength and better pore interconnectivity in comparison to 100% silk fibroin scaffold. After 48 h, cells seeded on scaffold with spidroin and fibroin mix had flattened morphology in comparison to silk fibroin scaffold which appeared to be more rounded on the scaffold surface. Scaffold with 10% (w/w) of silk spidroin (SS) + 90% (w/w) of silk fibroin (SF) was the most optimal composition for cell proliferation. Immunocytochemistry of integrin β1 and RGD sequence, showed that scaffold with SS 10% provide better cell attachment with the presence of RGD sequence from the spidroin silk which could explain the higher cell proliferation than SF100% scaffold. Based on Alcian Blue staining and Collagen Type II immunocytochemistry (ICC), cells grown on 10% SS + 90% SF scaffold with 10% PRP supplementation were the most optimal to support chondrogenesis of hWJ-MSCs. These results showed that the addition of spidroin silk from A. appensa. had impact on scaffold compressive strength and chondrogenic differentiation of hWJ-MSC and had the potential for further development of bio-based material scaffold in cartilage tissue engineering.
Abstract
Platina play a crucial role in catalytic converter device as one of catalyst that convert toxic gases in the exhaust gas emission to less toxic gas pollutant. The performance of this device ...can be significantly elevated by implementing platina nanoparticles (Pt NPs) because catalytic performance can be increased by decreasing its particles size. However, nanoparticles are not stable and tend to agglomerate, thus prohibit formation of nano particles. In this context, utilization of cellulose nano crystals (CNCs) in fabrication of Pt NPs are attractive due to their ability to encourage nucleation and prevent agglomeration of nanoparticles. In this study, Pt NPs was prepared by reduction of H2PtCl6 solution at various temperature (25, 33 and 40 °C) with the presence of CNCs. Based on visual observation, darker precipitate was observed by increasing temperature. Further characterization using UV-Vis spectroscopy showed that about 90% of Pt
4
+ in solution were successfully convert to dark particles at 40 °C. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) revealed that the dark particles in sample is Pt NPs with particles size 16.5 ± 3.2 nm.
A simplified approach for micromechanical modeling of fiber-reinforced polymer composite is proposed. A hexagonal-type single unit cell was subjected to four loading conditions to predict the ...effective properties of the unit cell. The unit cell properties with different fiber fractions were distributed randomly across n × n homogenized unit cells, which was expected to represent the random fiber distribution in the actual composite lamina. It was proved that the proposed homogenized multi-cells model could predict the composite transverse tensile stiffness and strength with a good agreement against experimental results and required much less computational cost compared to the classical fiber/matrix micromechanics model.
A numerical model of unidirectional carbon fiber-reinforced polymer composite material at the micro-level has been introduced to complement the experiment and analytical model in estimating the ...elastic properties of composite material. Idealization was performed in the model by using a periodically distributed fiber following square and hexagonal packing arrangement. The determination of the unit cell configuration was made by considering the periodic boundary condition associated with the selected configuration. The idealization using periodic fiber arrangement was proved to adequately estimate the elastic properties of composite material. The hexagonal model was proved to solve the drawbacks of the square model in estimating the shear properties with error reduction up to 50 % in comparison to the square model.
Tissue engineering scaffold is used to facilitate and support cell/tissue growth. Fabrication of silk fibroin scaffold using newly developed direct dissolution salt leaching method is successfully ...done. This method significantly reduces the processing time compared to the traditional method. Cells attachment, cells growth, cells migration, and diffusion of nutrients and waste are affected by the architecture scaffold. In this study, 3D analysis on porous architecture evaluation of direct dissolution salt leaching scaffolds is conducted. Scaffolds are fabricated from different NaCl particle sizes of 158, 250, 378, and 503 μm at 12% w/v silk fibroin concentration. Scaffold architecture is evaluated using microcomputed tomography (micro‐CT) method. Evaluation of scaffold architecture shows that the use of larger NaCl particle size increases the scaffold pore size. The relationship between scaffold pore size and scaffold porosity, scaffold wall thickness, pore interconnectivity, scaffold specific surface area is established, which is important for tissue formation.
One of the emerging challenges in tackling environmental issues is to treat electronic waste, with fast-growing battery waste as a notable threat to the environment. Proper recycling processes, ...particularly the conversion of waste to useful & value-added materials, are of great importance but not readily available. In this work, we report a facile and fast production of graphene from graphite extracted from spent Zn-C batteries. The graphene flakes are produced by electrochemically exfoliating graphite under varying DC voltages in poly(sodium 4-styrenesulfonate) (PSS) solution of different concentrations. The exfoliation takes place
via
the insertion of PSS into the interlayers of graphite to form C-S bonds as confirmed by FTIR and XPS studies. Under an applied voltage of 5 V and in 0.5 M PSS, high quality graphene flakes are obtained in a good yield, giving an
I
D
/
I
G
ratio of about 0.86 in Raman spectroscopy. The transparent conductive film prepared from the dispersion of high quality graphene flakes shows great promise due to its low sheet resistance (
R
s
) of 1.1 kΩ sq
−1
and high transmittance of 89%. This work illustrates an effective and low-cost method to realize large scale production of graphene from electronic waste.
Low defect ratio graphene with promising conductivity and transparency can be obtained from the spent graphite in Zn-C battery waste.
Natural fiber application due to its competitiveness attracted many research in green composites. However, the tensile properties of natural fiber composites might be influenced by several factors ...such as treatment of the fibers, manufacturing processes, and water absorption levels. In this research, we use petung bamboo fibers as natural fibers candidate for a good reinforcement in green composites. The study focused on the tensile property of bamboo fiber reinforced epoxy composites due to alkali treatment, manufacturing process, and water absorption. The composites were made with three variations: the fibers were varied without and with alkaline treatment (5% NaOH); manual lay-up method and hot press were applied as manufacturing variation; moisture content in the composites was varied in dry condition and after water absorption treatment. Tensile testing and Scanning Electron Microscope (SEM), were performed to improve tensile strength of composite and fiber-matrix interface quality. The alkali treatment has less effect to the tensile strength than of the volume fraction gain and the void content. Composite manufacturing by hot press has a significant effect to the improvement of tensile strength up to 37% compare to the hand lay-up method. Water absorption up to 8.8% had decreased the tensile strength of composites up to 29%. The alkali treatment on the bamboo fibers had effectively reduced water absorption into the composite as well as the tensile strength reduction.
Scaffold topography and culture medium conditions for human wharton's jelly mesenchymal stem cells (hWJ-MSC) are critical components of the approach to nucleus pulposus (NP) tissue engineering.
To ...evaluate the silk fibroin (SF) scaffold topography analysis (optimal thickness and pore diameter) and to determine culture medium conditions for the growth and differentiation of hWJ-MSC.
hWJ-MSCs were seeded into different thicknesses and pore size diameters and grown in different concentrations of glucose, platelet rich plasma (PRP) and oxygen. The cell-seeded scaffold was evaluated for cell attachment, growth and differentiation potency.
The results indicated that SF scaffold with a minimum thickness 3.5 mm and pore diameter of 500 μm with cells cultured under low glucose, 10% PRP and normoxia conditions induced the growth and differentiation of hWJ-MSCs, indicated by the accumulation of glycosaminoglycans content and the presence of type II collagen, as markers of NP-like cells.
Until recently, the best approach to replacing a degenerating nucleus pulposus (NP) remained unclear. Tissue engineering is the most current method utilized to develop 3D cultures on scaffolds that direct cells sources into NP-like cell given optimal scaffold topography and culture conditions. Human Wharton's jelly mesenchymal stem cells (hWJ-MSC) are considered suitable multipotent stem cells for NP tissue engineering. A 3D construct of silk fibroin scaffold with a suitable thickness and pore diameter can facilitate attachment, growth and differentiation of hWJ-MSC into NP-like cells. Culture conditions with low glucose concentration on medium supplemented with PRP in normal oxygen conditions enhance the NP extracellular matrix marker, an indication that these 3D constructs and culture conditions can be developed into NP-like cells.
In recent years, the research on sound-absorbing material has been directed to sustainable materials such as kenaf fiber and coconut coir fiber. Herein, this study offers the acoustic absorption ...performance of a novel natural fiber that is biduri fiber (Calotropis gigantea). Biduri fiber is a cellulose fiber that has a low density and a hollow structure along the fiber; hence, it has potential for sound absorption. Biduri fibers were thermally bonded with polyester fibers into nonwoven fabric. The sound absorption coefficient was measured using an impedance tube system, according to International Organization for Standardization (ISO) 10534-2:1998. The nonwoven fabric effectively absorbed high-frequency sound (2000-5000 Hz). The absorption coefficient reached 0.95 at 1600 Hz for nonwoven fabric with 95 wt.% of biduri fibers, a density of 25.9 kg m
−3
, and a thickness of 15-21 mm, which was better than glass wool and several natural fibers. Nonwoven fabrics with a thickness of 15-21 mm and ≥80 wt.% of biduri fibers met Indonesian National Standard 8443:2017 for high- and low-frequency sound silencers. Using the approximate relationship of the absorption coefficient between normal and random incidence sound, it was found that those nonwoven fabrics were categorized as class B sound-absorbing material according to ISO 11654:1997.
Polymeric materials have been employed in a wide range of applications in both dry and wet environments. When these materials suffer damage, it becomes crucial to initiate repairs in order to ...mitigate further losses. The use of self-healing materials emerges as a promising strategy not only to address this issue but also possess the advantage of prolonging the product’s lifespan. Nevertheless, the development of self-healing materials tailored for wet environments presents a set of obstacles and complexities. The review examines the current state of research in the field and highlights the challenges associated with developing self-healing materials that can effectively repair damage in such environments. We discuss the self-healing mechanisms and various polymers that are extensively employed in the advancement of self-healing materials. We study the progress made in the research and development of self-healing materials specifically designed for wet environments. Furthermore, it provides a summary of various applications of self-healing materials in wet environments.
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