The Fe(3)O(4)@SiO(2)@graphene microspheres were prepared and demonstrated to be highly efficient enrichment materials for proteins and peptides in MALDI-TOF MS analysis.

Graphene (G) is a new allotropic member of carbon with a unique two-dimensional and one-atom-thick sheet structure. It has attracted tremendous research interest in both academic and industrial areas due to its exceptional physical and chemical properties. [1][2][3] However, a serious problem in synthesis and application of G is aggregation. Due to the strong hydrophobic nature of G, G sheets have a strong tendency to aggregate to G clusters or even restack to graphite particles through van der Waals interactions. The resulting G agglomerates are very hard and insoluble in water or organic solvents, making further processing difficult. Since most of the exceptional properties of G can only be achieved with individual sheets, prevention of aggregation of G sheets is of particular importance for its applications.Aggregation of G can be reduced by using stabilizers. [4][5][6] However, attachment of foreign molecules onto G sheets may cause an adverse impact on the applications. As an alternative, graphene oxide (GO) has an excellent water dispersibility and has been used as a substitute for G in many applications. [3] GO is usually obtained by exfoliation of graphite oxide, [7][8] which can be synthesized from graphite. [9] However, the heavy oxidation during the synthesis can severely damage the large delocalized p-electron system of G and cause many imperfections and defects in the GO sheets. Thus, the unique electronic and optical absorption properties of G are seriously compromised in GO. Li et al. [10] reported the preparation of a processable aqueous dispersion of chemically converted G from GO; however, the obtained G dispersion was only stable under basic conditions and the reductant was difficult to remove from the dispersion. Therefore, facile and scalable methods for the synthesis of low-defect, well-dispersed, and clean G sheets are still urgently desired. Inspired by GO, we hypothesized that controlling the oxidation degree of G may provide a feasible approach for this purpose. However, although significant efforts have been made on developing synthetic strategies of G, little attention has been paid to controlling the oxidation degree of G. [11][12] Herein, we report a very simple method for the synthesis of mildly oxidized graphene by oxidizing chemically converted G with diluted nitric acid (2 m; Scheme 1A). We aimed to find a facile approach to prevent the aggregation of G sheets while maintaining the G structure as intact as possible. To distinguish from GO, the produced material is called acid-oxidized graphene (AOG). The AOG showed good dispersibility in water (up to 1 mg mL À1 ). Meanwhile, unlike GO (Scheme 1B), the main framework of G was not disrupted, and thus most of the exceptional properties of G can be maintained. Therefore, the AOG combines the advantages of G and GO while avoiding their disadvantages. Furthermore, the AOG contains no stabilizer molecules and can be highly pure, which is very favorable for its applications.We found that the AOG aqueous dispersion was rather stable. Eve...

a Graphene oxide nanoribbons (GONRs) were covalently functionalized with an antibody using polyethylene glycol (PEG) as a linker to produce a novel probe for surface enhanced laser desorption/ionization mass spectrometry (SELDI MS). This probe provides a highly sensitive and selective platform for enrichment and MS detection of small molecules in complex media.Detection of biologically important small molecules in complex media by mass spectrometry (MS) is of extreme importance. MS offers high sensitivity, reliability, and outstanding qualitative ability. However, its application is seriously hindered by the ionization suppression effect and matrix interferences. As a result, complicated sample preparation procedures are often required prior to MS analysis. Surface-enhanced laser desorption/ionization (SELDI), a derivant mode of matrix-assisted laser desorption/ionization (MALDI), provides a valuable technique for MS analysis.