Enhanced enrichment performance of nickel oxide nanoparticles via fabrication of a nanocomposite with a graphene template

Abstract

Metal oxide based nanocomposites are applied in phosphoproteomics for enrichment through the surface hydroxyl groups of metal oxides, though the role of the metal is rarely described. Using graphene as a template after modification with nickel oxide, a nanocomposite with an increased surface area is fabricated and applied to phosphopeptides. Characterisation shows a narrow size distribution of 15-20 nm, BET surface area of 179.70 m 2 g À1 and a pore volume of 0.44 cm 3 g À1 . The graphene possesses well distributed NiO nanoparticles showing selectivity up to 1000 folds of complexity with a sensitivity as low as 1 femtomole. The G-NiO nanocomposite shows a higher selectivity towards phosphopeptides compared to TiO 2 , ZrO 2 and NiO nanoparticles. The enrichment with the G-NiO nanocomposite is tested for biological samples like egg yolk, non-fat milk and human serum. Phosphopeptides having phosphorylations of up to 6 phosphate groups, derived from phosvitin and lipovitellin, are enriched in the egg yolk digest. Phosphopeptides characteristic of casein variants are enriched in the non-fat milk digest with a recovery of aS1 21.9%, aS2 30% and b-casein 20%. Phosphorylated proteins are identified in human serum through the enrichment of phosphopeptides. † Electronic supplementary information (ESI) available: Additional information regarding the preparation of the HeLa cell extract. See: Fig. S1 for phosphopeptides enrichment of b-casein, Fig. S2 for comparison to metal oxide NPs, Fig. S3 for bottom-up identication of serum phosphoproteins and Table S1 for enrichment from serum. See

Microwave-assisted synthesis of void-induced graphene-wrapped nickel oxide hybrids for supercapacitor applications

“…Also the MEGO has a negatively charged surface due to the presence of carboxylic, hydroxyl and epoxy groups which bind nickel oxide through electrostatic interactions. [61][62][63][64] The decomposition of nickel nitrate salt provides, positively charged Ni 2+ ions, which gets attracted towards these functional group sites due to the electrostatic force between Ni 2+ ions and polar negatively charged functional groups on the surface. [64][65][66] The Ni 2+ ions react with functional groups containing MEGO sheets, leading to the local creation of bridge, as Ni-O-C bonding.…”

“…[61][62][63][64] The decomposition of nickel nitrate salt provides, positively charged Ni 2+ ions, which gets attracted towards these functional group sites due to the electrostatic force between Ni 2+ ions and polar negatively charged functional groups on the surface. [64][65][66] The Ni 2+ ions react with functional groups containing MEGO sheets, leading to the local creation of bridge, as Ni-O-C bonding. 67 This leads to the formation of Ni(OH) 2 with hydroxyl group or NiO with epoxy group on the surfaces of MEGO and acts as a nucleation centre for the further growth of NiO nanoparticles.…”

Graphene oxide–metal oxide nanocomposites for on‐target enrichment and analysis of phosphorylated biomolecules

“…Metal oxides of transition metals (TiO 2 [4], ZrO 2 [5], and Ta 2 O 5 [6]) and lanthanides (La 2 O 3 [7], HfO 2 [8], and CeO 2 [9]) as micro‐ and nano‐materials or composites enrich phospho‐moieties via solid‐phase batch extraction [10]. Composites of graphene oxide (GO) with metal oxides such as TiO 2 [11], nickel oxide [12], and molybdenum oxide [13] enrich phosphopeptides through batch extraction. The monolithic surface is modified with Fe 2 O 3 nanoparticles [14] and metal ions like Zr 2+ [15] showing efficient phosphopeptides enrichment.…”

Preparation of graphene–hafnium oxide composite for selective enrichment and analysis of phosphopeptides

“…5,6 It was recently reported that graphene oxides decorated with metal oxide nanoparticles can be used to capture biomolecules from complex biological samples. [7][8][9][10] The reversible phosphorylation of proteins is one of the most signicant post-translational modication processes, and plays a crucial role in many regulatory mechanisms, including cellular growth, metabolism, differentiation, cell-cycle control, signal transduction, proliferation, and apoptosis. [11][12][13] Abnormal phosphorylation can be seen as the molecular signatures of organisms in a specic physiological state, and could provide valuable information for the early diagnosis of numerous diseases.…”