The Fluorescence Properties Of Quinoline Derivatives And The Synthesis Of Magnetic Nanoparticles And Their Tunable Peroxidase-Like Activity

Quinoline-based fluorescence probes play a crucial role in optoelectronic and biomedicine studies. Recently, many studies used quinoline scaffolds as fluorescence chemical cores to investigate small molecule functions. On account of the coordination structure of nitrogen heterocyclic, quinoline derivatives appear quite attractive with fluorescent properties.In the first experimental section, we use acetanilid as raw material, synthesized quinoline-2-one-3-carbaldehyde through Vilsmeier-Haack reaction and dechlorine reaction under70%acetic acid condition. Then, a new Schiff-base ligand (L1) with good fluorescence response to Al3+, derived from2-oxo-quinoline-3-carbaldehyde and nicotinic hydrazide, had been synthesized and investigated in this paper. Spectroscopic investigation revealed that the compound L1exhibited a high selectivity and sensitivity toward Al (Ⅲ) ions over other commonly coexisting metal ions in ethanol, and the detection limit of Al3+ions is at the parts per billion level. The mass spectra and Job’s plot confirmed the1:1stoichiometry between L1and Al3+. Potential utilization of L1as intracellular sensors of Al3+ions in human cancer (HeLa) cells was also examined by confocal fluorescence microscopy.Recent studies have suggested that the physical and chemical properties of nanoparticles (NPs) strongly depend on local chemical composition, size, and shape. Nowadways, thermal decomposition method has proven to be an ideal approach for preparing monodisperse CoFe2O4NPs with high yield, narrow size distribution, and good crystallinity, and the shape and size of the NPs using this method were controlled by adjusting the surfactant to precursor ratio, heating rate, stirring, and seed mediated growth during the reaction. However, these control methods require precise process management of environmental conditions or necessitate tedious multistep reaction that are not necessarily amenable to large scale NP synthesis. In addition, to date, very little has been explored on the effect of the shape and size on the catalytic properties of peroxidase nanomimetics of cobalt ferrite nanostructures and little is known about the effects of different CoFe2O4nanostructures on biocatalysis.In the second experimental section, we report a new precursors-mediated growth of monodisperse magnetic cobalt ferrite (CoFe2O4) NPs with controlled size and shape. CoFe2O4NPs with corner-grown cubic, cubic and plate-like can be successfully prepared by simple tuning the amount of iron and cobalt acetylacetonates in oleic acid. Interestingly, the product shape varies from cubic to starlike by only changing the reaction temperature from320℃to330℃. These NPs exhibit size and shape-dependent peroxidase-like activity towards3,3,5,5,-tetramethylbenzdine (TMB) in the presence of H2O2, and thus exhibited different levels of peroxidase-like activities, in the order of spherical> cubic> starlike> corner-grown cubic> plate-like; this order was closely related to their particle size and crystal morphology. CoFe2O4NPs exhibited high stability in the HAc-NaAc buffer (pH=4.0) and high activity over a broad pH (2.5-6.0). Furthermore, the Michaelis constants Km value for the CoFe2O4NPs (0.006mM) with TMB as the substrate was lower than HRP (0.062mM) and Fe3O4NPs (0.010mM). Such investigation is of great significance for peroxidase nanomimetics with enhanced activity and utilization.In the third experimental section, we synthesized a metal doped nanomaterial on the basis of Fe3O4magnetic nanoparticles. The Fe3O4-CexOy magnetic composite material exhibits apparent superparamagnetism as Fe3O4, meanwhile, its catalytic properties of peroxidase is much higher than Fe3O4. Furthermore, Fe3O4-CexOy shows excellent peroxidase-like activity over a broad pH range includes a near neutral pH.