Synthesis, Property And Application Study Of N-(Aminobutyl)-N-(Ethylisoluminol)/Horse Radish Peroxidase Bifunctionalized Graphene Oxide Hybrids

In this dissertation, the state of arts in the field of chemiluminescence (CL), catalyst-based CL and CL functionalized nanomaterials, especially for the functionalization of graphene and its application were reviewed. Graphene oxides (GO) have been regarded as an ideal platform for the synthesis of novel functionalized nanomaterials due to their unique two-dimensional structure, large surface area, excellent optics and electric property as well as ease of self-assembly. To date, GO hybrid materials noncovalently functionalized by lucigenin, luminol and N-(aminobutyl)-N-(ethylisoluminol)(ABEI) have been successfully synthesized. And take advantage of those functional materials as signal probes or sensing interfaces shows promising application potential in the field of bioassays and biosensing. However, the synthesized chemiluminescent GO hybrids were purified by dialysis for more than2days, which was tedious and time-consuming. Moreover, the restricted CL efficiency of the chemiluminescent GO hybrids mentioned above remains a great challenge for the detection of trace substances in the biological systems. Therefore, it is very important to explore GO hybrids bifunctionalized by CL reagents and catalysts in order to achieve excellent CL activity as well as other physical and chemical features and to develop highly sensitive and selective sensors. In this dissertation, the synthesis, characterization, CL property and CL mechanism of ABEI and HRP bifunctionalized GO hybrids were investigated. A highly chemiluminescent GO hybrid was obtained. By virtue of N-(aminobutyl)-N-(ethylisoluminol) and horseradish peroxidase bifunctionalized graphene oxide GO hybrid (ABEI-GO@HRP) as a platform, an ultra-sensitive, selective and reagentless CL sensor was developed for H2O2detection.Firstly, a facile strategy for the preparation of ABEIand HRP bifunctionalized graphene oxide GO hybrids (ABEI-GO@HRP) was reported for the first time. In this strategy, ABEI molecules were first attached on the surface of GO via π-π interactions and then HRP as a catalyst was assembled on the surface of GO-based composite by noncovalent interaction. The as-prepared ABEI-GO@HRP hybrids were just purificated by simple centrifugation. The synthesis and purification of ABEI-GO@HRP hybrids are simple, green, and convenient. The composition of the as-prepared ABEI-GO@HRP hybrids was investigated by X-ray photoelectron spectroscopy, circular dichroism spectra and FT-infrared spectroscopy. The results demonstrated that both of ABEI and HRP were successfully functionalized on the surface of GO. The assembly mechanism of ABEI-GO@HRP was explored by using atomic force spectroscopy, UV-visible spectroscopy and fluorescence spectroscopy. The results indicated that the GO is successfully functionalized by ABEI and HRP molecules via non-covalent interactions with HRP/ABEI/GO/ABEI/HRP sandwich structure.Next, in order to study the property of the new hybrids, the CL behavior and mechanism of ABEI-GO@HRP were investigated by static injection. When reacted with H2O2, the hybrids exhibited excellent CL activity over a wide range of pH from6.1to13.0, whereas ABEI functionalized GO had no CL emission at neutral pH and showed more than2orders of magnitude lower CL intensity than ABEI-GO@HRP at pH13.0. Such strong CL emission from ABEI-GO@HRP was probably due to that HRP and GO facilitated the formation of O2·-,-CO4·2-, HO· and π-C=C· in the CL reaction, and GO as a platform promoted the electron transfer of the radical-involved reaction.Finally, by virtue of ABEI-GO@HRP as a platform, an ultra-sensitive, selective and reagentless CL sensor was developed for H2O2detection. Attributing to excellent catalytic activity and enzymatic specificity of HRP, the CL sensor exhibited a wide linear range and low detection limit at pH8.0or pH13.0, which were better than the previously reported methods. This work provides an effective tool for the determination of H2O2in neutral and alkaline conditions.This work provides an exciting new member in the family of CL regent and its catalyst bifunctionalized GO hybrids and reveals that GO is an excellent interface for the immobilization of ABEI and HRP. The bifunctionalization of GO by ABEI and HRP leads to excellent CL feature, catalytic property, enzyme selectivity, solubility and easy purification, which can be used as an ideal platform for the development of novel analytical methods. It is of great application potential in ultrasensitive biosensing and biomedical applications.