Application Of Near Infrared (NIR)-absorbing Nanomaterials In Photothermal Therapy And Catalysis

In this thesis, several nanomaterials, such as graphene, polypyrrole and Prussian blue nanoparticles, which was with high-near infrared absorption, were prepared, characterized and applied in photothermal therapy and catalysis. Six chapters are included in this thesis:In chapter 1, the developments, preparations and applications of grapheme, polypyrrole and Prussian blue were reviewed in detail. Meanwhile, the research purpose and content of this thesis were described in brief:In chapter 2, to prepare rGO from as-prepared water-soluble graphene oxide (GO), five reducing agents including Green Tea, dopamine, ascorbic acid-, hydrazine hydrate and bovine serum were used as reducing agent. The obtained rGO nanomaterials were characterized by Raman, XRD and FT-IR. Furthermore, the heating rate in aqueous solution and the dispersibility in water solution and bovine serum solution of rGO were investigated. The results showed that the rGO reduced by dopamine was the most suitable material for photothermal therapy.In chapter 3, the rGO nanomaterials reduced by dopamine were characterized by TEM, AFM, UV-vis and FT-IR. The results showed that rGO nanomaterials have been achieved successfully and a polydopamine film was formed on their surface. After that, the targeting molecules such as folic acid (FA) were introduced on the rGO surface by electrostatic interaction and the drug of DOX was loaded on the rGO surface by π-π interaction. The cell mortality rate of rGO-FA+DOX sample was investigated by MTT method after irradiated by a NIR laser (808 nm,2 W/cm2), while the free rGO and DOX samples were used as control groups. The results of the experiments showed that in comparison to the bare rGO and DOX, the rGO-FA+DOX sample exhibited an 81% death rate of Hela cells, which resulting from the synergy effect of phototherapy and chemotherapy.In chapter 4-6, firstly, the morphology and structure of several nano materials including polypyrrole (ppy), Prussian blue (PB) and ppy@PB were characterized by SEM, TEM and FT-IR. The effects of parameters on the catalytic oxidation of TMB in the presence of above materials, such as pH, temperature and H2O2 concentration were investigated. The catalytic mechanism and the dynamic characteristics of three kinds of systems were researched in detail. These materials can be applied in the detection of GSH and glucose, also in the degradation of methylene blue. And the main contents are listed as follows:First, the peroxidase-like activity of the polypyrrole, Prussian blue and ppy@PB was investigated through the catalytic oxidation of the peroxidase substrate 3,3’,5,5’-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue color reaction; Second, the mechanism of these three catalyst system is demonstrated as Fenton reaction, which strong oxidizing hydroxyl radicals are produced by prompting H2O2 and the hydroxyl radicals can guide the followed catalytic process; Third, the reaction rate and affinity to substrate of three systems are faster and better than of horseradish peroxidase (HRP), which means that they can replace HRP in the detection of H2O2; Forth, the reaction rate of the ppy@PB nanocomposites compared with polypyrrole, have enhanced almost one order of magnitude, which showing the advantage of composite materials; Fifth, the detection limit of GSH was down to 0.841 uM by using ppy as catalyst. In the glucose detection, the detection limit was 1.1 μM by using Prussian blue as catalyst. In addition, the degradation efficiency of methylene blue was as high as 98.13%. When ppy@PB nanocomposites were catalyst, the detections limit of glucose and GSH were 0.615 μM and 0.579 μM, respectively.