In situ syntheses of hydroxyapatite‐grafted graphene oxide composites

Abstract

In this study, we examined three different syntheses of hydroxyapatite (HAp) and graphene oxide–hydroxyapatite (GO–HAp) composites with a GO content of 9, 33, and 43% wt. The materials were prepared from various precursors of calcium and phosphate ions, using an in situ synthesis method, with mild conditions to avoid reducing the GO. In situ bonding technology proposed that calcium ions bond with GO at first and then HAp nanoflakes in situ grow on GO sheets, forming GO–HAp nanocomposite. The aim of the present work was to analyze the differences due to the use of different starting reagents and verify, with the addition of increasing amounts of GO, the changes in morphology, crystallinity, and solubility of the obtained HAp composites. Detailed structural and morphological characterization studies of the composites were carried out using scanning electron microscopy, energy dispersive X‐ray spectrometry, X‐ray powder diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy. We found that GO sheets act as a nucleation site for HAp mineralization, but we observed a loss of the crystallographic order due to the intercalation of the graphenic sheets between the HAp particles.

Experimental Design and Response Surface Methodology Applied to Graphene Oxide Reduction for Adsorption of Triazine Herbicides

“…The absorption peaks at about 1423, 1225, and 1060 cm –1 are assigned to −OH from carboxyl, C–O–C from epoxy or ether and C–O from alkoxy, respectively. These results are in agreement with the literature …”

“…Graphene oxide was synthesized using a modified Hummers method. , Graphite (5 g) and sodium nitrate (3.8 g) were placed in a beaker in a salt/ice bath. Subsequently, 375 mL of concentrated sulfuric acid was added.…”

In situ synthesis of hydroxyapatite nanorods on graphene oxide nanosheets and their reinforcement in biopolymer scaffold

“…Previous reports have demonstrated that the abundant mineralization related groups (epoxide, and carboxylic groups) on GO surface can act as effective nucleation sites for precipitating Ca 2+ , and then regulate the nucleation and growth process of HAP nanocrystals [21] , [22] . The HAP nanocrystals can form tight interfacial bonding with GO nanosheets and distribute homogeneously on the surface of GO nanosheets thus avoiding their aggregation [23] , [24] , [25] .…”

New Sustainable, Scalable and One-Step Synthesis of Iron Oxide Nanoparticles by Ion Exchange Process

“…To date, a lot of synthesis routes have been developed, starting both from chemical, physical, and biological methods. Specifically, the most used iron oxide NPs synthesis methods, due to their relative simplicity and the ability to have a good control of the particles’ shape and size, include chemical precipitation, hydrothermal, sol–gel, electro-deposition, emulsion precipitation, surfactant mediated precipitation, microemulsion precipitation, and microwave assisted hydrothermal technique [ 9 , 10 , 11 , 12 , 13 , 14 ]. Therefore, the main synthesis techniques are generally based on chemical routes, which, as disadvantages, often require the necessity of high temperature/pressure and always need extra purification steps to remove organic substances and/or secondary products.…”