Preparation Of Multifunctional Nanomaterials And Their Application In The Field Of Optical Assays

Due to their unique chemical, physical and biological properties, nanomaterials have attracted great research interest. It is highly desirable to integrate two or more different components into a micrometer or submicrometer sized multifunctional particles for their important applications in modern industrial, biomedical and analytical chemistry. This paper mainly focuses on designing the multifunctional nanocomposites and investigating their applications in the fields of optical analysis. First, we synthesized a series of phenol formaldehyde resin (PFR) based PFR fluorescence resonance energy transfer (FRET) probes by changing the prepared conditions of PFR. Then the as-synthesized nano-probes had been applied in determination of heavy metal ions, assaying biological molecules and photothermal therapy to kill tumor cells. In addition, PtCo bimetallic alloys were loaded on the surface of graphene, which could catalyze the chemiluminescence (CL) of luminol-H2O2strongly. Thus, a novel CL method has been developed for sensitive detection of glucose. The detail can be summarized as follows:1. On the basis of the reported method about PFR, we synthesized the PFR nanoparticles (NPs) with controllable size and UV absorption spectrum through adjusting the ratio of PFR precursors. The amino were modified on the surface NPs through loading the polymer electrolytes of polyethylenimine (PEI) on the PFR shell. Through the coupling reaction between amino and carboxyl groups, the CdTe quantum dots prepared with thioglycolic acid were loaded on the surface of polymer electrolytes functionalized PFR. Thus, a novel FRET system consists of CdTe quantum dots and PFR as donor and acceptor was established. Cu2+has sensitive response to the fluorescence intensity of the as-synthesized CdTe QDs-PFR nanocomposites. So we developed a FRET nano-probe for sensitive detection of Cu2+with visual assays method.2. The prepared Fe3O4magnetic NPs with uniform size were mixed with PFR precursor at160℃for6hours to obtain a kind of green fluorescence Fe3O4@PFR nanocomposites. As the polymer electrolytes were loaded on the FPR shell, the as-synthesized Fe3O4@PFR with positive charge can absorbed the Au NPs prepared with citric acid method. So, we synthesized the Fe3O4@PFR@Au nanocomposites with strong magnetism and fluorescence. The good biocompatible Fe3O4@PFR@Au nanocomposites has been applied in detection of thiols thanks to the strong interaction between the thiols compounds and Au NPs. Herein, a sensitive FRET probe was used for the thiols molecules detection in living cells.3. The solid Ag@PFR NPs can be changed into porous structure through pre-heating the precursor solution of Ag@PFR. After mixing the porous Ag@FPR NPs and HAuCl4for1h at85℃, rich hydroxyl groups in PFR can reduce Au ions into Au NPs in the PFR without additional reducing agents and surfactants. Au layer even can be formed along the inner surface of PFR with the increasing of Au ions in solution. Compared with the typical seed-mediated process, this method overcomes the shortcoming of detaching of Au seeds from the core surface, which improves the reproducibility of synthesis and the optical stability of the product. Furthermore, due to the modified folic acid (FA) on the PFR shell, the as-synthesized nanocomposites can trap the tumor cells specifically. Thus, featuring tunable optical properties, good biocompatibility and strong targeting, the multilayer nanocomposites have been utilized to kill tumor cells with photothermal therapy method.4. In order to combine the catalytic activity of graphene with bimetallic NPs, the Pt-Co bimetallic alloys were loaded on the surface of graphene at room temperature. Compared to other method for synthesis of graphene based nanocomposites, no complicated process and expensive reagents or equipments were needed to obtain as-synthesized nanocomposites. The as-synthesized PtCo/graphene can strongly catalyze the CL intensity of luminol-H2O2. Moreover, the concentration of H2O2is linear with the increased CL intensity at a low concentration range. It was more sensitive for H2O2detection than other CL system. Based on that, a CL method has also been established for the determination of glucose sensitively.