| There are various metal ions that have special physiological functions in organism, and play an important role in the process of life. The properties such as the type, valence and concentration of metal ions directly determine their function and the role of organisms and the environment, so it’s of great significance of the high specificity and sensitivity detection of the metal ion. Iron and copper are both indispensable trace element to human body, participating in a variety of physiological processes in the body and having the very vital significance to human health.A number of detections based on nanoparticles and functional nucleic acid has become a hot topic, meanwhile it is significant in building new detection system to metal ions. Based on this we chose silica-encapsulated silver nanoparticles (Ag@SiO2 NPs) and copper-dependent DNAzyme as our main materials, realized the detection with simple, efficient and high sensitivity of iron and copper ion, respecticely, using Raman spectrometer and Ultraviolet and visible spectrophotometer. Finally, we established the method for the analysis of iron and copper ion based ceruloplasmin, which can detect the ceruloplasmin effectively, then can be applied in disease diagnosis. It could also act as an important reference in building new detection system to other metal ions. The results are showed as follows:1. Detection of iron ion by SERS based on silver@SiO2 nanoparticlesThe silica-encapsulated silver nanoparticles (Ag@SiO2 NPs) with well monodispersity and uniformity was synthesized in aqueous phase at room temperature and acted as SERS substrate to establish a simple, rapid, high sensitive and new method for the detection of iron ion in virus serum with the characteristic Raman peaks at 1408 cm-1 and 1445 cm-1 of the complex compound Fe-Phenanthroline, the limit of detection (LOD) for Fe2+ can reach 1×10-2 μg/mL, i.e.1 μg/100 mL, Ca2+, Cu2+, K+, Mg2+, Na+and Zn2+ were acted as interfering ion in the test, the results showed that the selectivity and specificity of the proposed method were both very high. The total content of iron in virus serum can be detected by reducing the Fe3+ to Fe2+ and according to the difference value before and after the reduction the content of the Fe3+ also can be calculated.2. Detection of copper ion by colorimetric assay based on DNAzymeIn this section, we reported a visual method which used Ultraviolet and visible spectrophotometer based on the DNAzyme with G-quadruplex structure to test the copper ion in serum. There is low interference with some common metal ions for the detection of copper. The results of this method and atomic absorption spectrophotometry are consistent. The limit of detection (LOD) for Cu2+ can reach 1.0×10-2 mmol/L, i.e.64 μg/100 mL. Ca2+, Cd2+, Fe2+, Hg2+, K+, Mg2+, Mn2+, Na+, Pb2+ and Zn2+ were acted as interfering ion in the test, the results showed that the selectivity and specificity of the proposed method were both very high. Furthermore, this method can also be applied to detecting DNA.3. Analysis of iron and copper ion based ceruloplasminThe ceruloplasmin served as ferrous oxidase, so we implemented a preliminary study on its catalytic efficiency, and it turned out that ceruloplasmin had the best catalytic activity under the condition of 60℃, pH 5.0. Then we combined silica-encapsulated silver nanoparticles and DNAzyme sensor mentioned previously to establish the method for the analysis of iron and copper ion based ceruloplasmin using Raman spectroscopy and UV-Vis spectrophotometer as detector. Ca2+, Cd2+, K+, Mg2+, Mn2+, Na+, Pb2+ and Zn2+ were acted as interfering ion in the test, the results showed that the selectivity and specificity of the proposed method were both very high. Meanwhile, through the detection of copper ions with high sensitive, we can adopt it to detect ceruloplasmin, which is iconic protein of lots of disease. It will play an important role in disease diagnosis, and also provides a new approach for pathological study. |
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