Preparation And Detection Of Peptides And Proteins Is Applied Functionalized Graphene Oxide

Graphene (G), a single layer of sp2-hybridized carbon atoms, densely packed in a two-dimensional (2D) honeycomb lattice. It is the basic/fundamental building block of other well-known carbon forms including zero-dimensionl (OD) fullerenes, one-dimensional (ID) carbon nanotubes, and three-dimensional (3D) graphite. Ever since its discovery in2004, graphene has attracted tremendous interest and become a sparkling rising star in the field of material material science, physics, chemistry and biotechnology due to its remarkable physicochemical properties. Graphene oxide (GO) is a precursor for graphene synthesis by chemical reduction with highly oxygenated surfaces, bearing epoxide, hydroxyl, epoxy, carbonyl, and carboxyl functional groups. These make GO sheets strongly hydrophilic and chemical reactivity, allowing them to reasily disperse in many solvents, particularly in water, and easily further modified by many other molecules. Graphene-based nanomaterials have been explored in various fields including supercapacitor, batteries, nanoelectronics, catalysis, sensors, and biomedicine. In this work, we tried several methods to prepare GO-based composites for protein and peptide enrichment and detection based on the extraordinary and superior properties of GO. The main contents of the paper are given as follows:In the chapter1, after a short introduction to graphene and GO, we reviewed the synthesis methods of graphene and GO, the functionalization techniques of graphene and GO, and the application of modified graphene and GO for the absorption, enrichment and detection of peptides and proteins.In the chapter2, a magnetic graphene oxide composite (Fe3O4/GO) was successfully synthesized. The morphology and structure of composite were investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The adsorption property of Fe3O4/GO composite for peptides and proteins was investigated by combine with ultra-performance liquid chromatography (UPLC). The results indicated that Fe3O4/GO with targets were easily separated from the aqueous solution by an external magnetic flied. Fe3O4/GO composite had good adsorption capacity for peptides and proteins, and the adsorption mechanism of the composite was affected by both molecular weight and structure of target molecules.In the chapter3, a facile and novel strategy was developed to fabricate magnetite/graphene oxide/chitosan (Fe3O1/GO/CS) composite, and the phase composition, chemical structure, morphology, magnetism and thermostability of the obtained composite were characterized by composite was characterized by FT-IR, XRD, scanning electron microscopy (SEM), TEM, vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA). Protein Cytochrome c (Cyt c) was chosen as model target to evaluate the adsorptive property of Fe3O4/GO/CS. The adsorption kinetics and adsorption isotherm of Cyt c on Fe3O4/GO/CS were investigated. The adsorption achieved equilibrium in a short time about40min. The adsorption date could fit the Langmuir model, and the maximum adsorption capacity was13.3mg/g. After enrichment procedure and magnetic separation, protein bounded with the material was analyzed by matrix assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) without desorption. The peak intensity and S/N ratio were significantly increased. The results indicated that Fe3O4/GO/CS composite exhibited a good adsorptive capacity for protein.In the chapter4, GO was surface-modified by Poly(ethylene glycol) bis-(3-aminopropyl) terminated (1.5kDa-1-NH2-PEG-NH2), the obtained composite was designed as GO-PEG. The UV-Vis spectrum showed that maximum absorption peaks of GO-PEG was red shift compared to GO. TEM images showed that GO-PEG was cleavaged into ultrasmall nanosheets, and the dispersibility in physiological solutions was improved. In this study, GO-PEG was used as a fluorescence quencher for developed a fluorescence resonance energy transfer (FRET) aptasensor for Lysozyme (Lys) detection based on the high fluorescence quenching efficiency, excellent stability and biocompatibility of the composite. The results suggested that the fluorescence of the dye labeled aptamer was quenched quickly and efficiently by GO-PEG. The fluorescence could recovery by the addition of Lys. A good linearity was observed in the range of50-300nM, and the limit of detection (S/N=3) of the method for Lys was about11nM...