Nano Hybrids Vol. 7

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Authors: Eduardo Salas-Bañales, R. Iris Y. Quiroz-Segoviano, Fernando Rojas-González, Antonio Campero, Miguel A. García-Sánchez
Abstract: While searching for adequate sol-gel methodologies for successfully trapping in monomeric and stable form either porphyrins or phthalocyanines, inside translucent monolithic silica xerogels, it was discovered that the interactions of these trapped tetrapyrrole macrocycles with Si-OH surface groups inhibit or spoil the efficient display of physicochemical, especially optical, properties of the confined species. Consequently, we have developed strategies to keep the inserted macrocycle species as far as possible from these interferences by substituting the surface -OH groups for alkyl or aryl groups or trapping these species inside alternative metal oxide networks, such as ZrO2, TiO2, and Al2O3. In the present manuscript, we present, for the first time to our knowledge, a methodology for preserving the spectroscopic characteristics of metal tetrasulfophthalocyanines and cobalt tetraphenylporphyrins trapped inside the pores of ZrO2 xerogels. The results obtained are contrasting with analogous silica systems and demonstrate that, in ZrO2 networks, the macrocyclic species remain trapped in stable and monomeric form while keeping their original spectroscopic characteristics in a better way than when captured inside silica systems. This outcome imply a lower hydrophilic character linked to the existence of a smaller amount of surface hydroxyl groups in ZrO2 networks, if compared to analogous SiO2 xerogel systems. The development and study of the possibility of trapping or fixing synthetic or natural tetrapyrrole macrocycles inside inorganic networks suggest the possibility of synthesizing hybrid solid systems suitable for important applications in technological areas such as optics, catalysis, sensoring and medicine
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Authors: Mostafa Ghiasi, Elham Naghashzargar, Dariush Semnani
Abstract: In recent years, the use of combined nanofibers with textile structures for various applications such as tissue engineering has been highly regarded. Among the different methods, electrospinning mechanism is more important to produce polymeric nanofibers in extensive diameters that has been used to fabricate silk fibroin nanofibers in this research. On the basis of the statistical analysis and analytic hierarchy process optimization method, the optimum electrospinning parameters to produce good morphology of nanofibers and the best conditions of texturing process to fabricate suitable structure of textured silk yarn have been obtained, respectively. The following step to produce nanocoated textured yarn was defined as a nanocoating process on the surface of textured silk yarn. Finally, the morphological and mechanical properties of these samples including no-textured silk yarn, textured silk yarn and nanocoated textured silk yarn analyzed and compared. Based on the finding of this study, the nanocoated textured silk yarn was found to be a promising construct for engineered scaffolds in tendon and ligament tissue engineering.
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Authors: Ahmad Siti Nurasikin, Hashim Norhayati, Nur Hidayah Yusri, Illyas Md Isa, Azlan Kamari, Azmi Mohamed, Muhammad Ibrahim Mohd Damanhuri
Abstract: A new layered-double hydroxide-3-(4-hydroxyphenyl) propionate (LDH-HPP) has been synthesized by intercalation of 3-(4-hydroxyphenyl) propionic acid (HPP) into Zn-Al-layered double hydroxide (LDH) by ion-exchange method. PXRD, FTIR, TGA/DTG, compositional studies and FESEM were used to characterize the synthesized nanocomposite. The intercalation of HPP into the interlayer gallery space of LDH was characterized by x-ray diffractogram showed expanded basal spacing of the value of 17.1 Å. The FTIR spectra of LDH-HPP nanocomposite synthesis by 0.025M HPP resembled a mixture of both FTIR spectra of HPP and LDH. Thermal analysis of LDH-HPP nanocomposite shows a better thermal stability as compared to the pure HPP, which proved that the intercalation of HPP into LDH interlayer enhanced the thermal stability of the HPP.
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Authors: Amlan Kumar Das, Avinash Marwal, Ruchi Verma
Abstract: Over the past two decades, there have been increased emphases on the topic of green chemistry and chemical processes. Utilization of non toxic chemicals, environmentally benign solvents, and renewable materials are some of the key issues that merit important consideration in a green synthetic strategy. The Datura Inoxia leaves possesses biomolecules such as cardiac glycosides, proteins, phenolic compounds, flavonoids and sugar, which could be used as reducing agent to react with ferrous and ferric ions and as scaffolds to direct the formation of Fe3O4 NPs in solution. To the best of our knowledge, the use of Dhatura innoxia plant extract at room temperature for the bio-reductive synthesis of Fe3O4 nanoparticles has not been reported. The formation of the Fe3O4 magnetic nanoparticles was first monitored using UV-Vis absorption spectroscopy. FT-IR spectroscopy and TGA/DTG analysis further confirms the formation of plant protein coated magnetite nanobio hybrid. The dried form of synthesized nanoparticles was further characterized using XRD, TEM.
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Authors: Mohammad Mizanur Rahman, M. Nasiruzzaman Shaikh
Abstract: A series of cross-linked waterborne polyurethane/hexamethoxymethylmel-amine-carbon nanotube nanocomposites (WBPU/HMMM-CNT) were synthesized using carboxylic group functionalized CNT. The carboxylic groups on CNT were reacted with the methoxy groups of HMMM to get bonded HMMM-CNT. Unreacted methoxy group of HMMM-CNT was crosslinked with the carboxylic acid salt groups of WBPU and made crosslinked WBPU/HMMM-CNT nanocomposite. The mechanical properties (tensile strength and Young’s modulus) of conventional WBPU, crosslinked WBPU/HMMM, WBPU/CNT and WBPU/HMMM-CNT nanocomposites were compared under three conditions: untreated, wet and dried. It was observed that the mechanical properties of the crosslinked WBPU/HMMM-CNT nanocomposites were the least affected by water compared to conventional WBPU, crosslinked WBPU/HMMM, and WBPU/CNT nanocomposites. Differential scanning calorimetry (DSC) analysis also confirmed that the WBPU/HMMM-CNT nanocomposite can absorbed least water which can be easily removed by heating without destroying their crystalline structure. Crosslinked WBPU/HMMM-CNT nanocomposite recovered most of its mechanical properties of (with optimum HMMM-CNT content) after drying.
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