Based On Optical Properties And Catalytic Properties Of Silicon Dots For Detection Of Biological Molecules

Nanoparticles have excellent opitcal, electric performance and good biocompatibility, which are widely used in chemical/biological sensor, cell imaging, medical and other fields. As an inert, non-toxic, rich in content and low cost of nano materials, silicon nanometer materials will be play an important role in the field of chemical/biological sensor and clinical analysis because of its excellent optical, electrical, mechanical properties and modifiable surface. Based on the nature of silicon nanomaterials, this paper research its new performance by using the properties of the silicon nanometer design a series of simple operation, high sensitivity, low cost of nano biosensors for hypochlorous acid, quercetin and glucose detection. The main contents are as follows:(1) The Silicon wafer is used as the silicon source, auxiliary by heteropoly acid electrochemical etching method in ethanol solution, no other modification and fluorescent properties of is obtained by simple ultrasound pyrolysis. Using the methods of TEM, ED, FTIR and UV-vis, we discusses the basic structure and optical properties of the obtained Si-dots and the influence of its luminous intensity under different pH, temperature and light bleaching. Experiment found that the preparation of Si-dots have good water dispersion, particle size uniform, adjustable emission wavelength, good stability and resistance to photobleaching. Experiment found that under acid condition hypochlorite can fluorescence quenching Si-dots, we have discussed the mechanism of corresponding quenching Si-dots in this paper, and build a kind of simple, high sensitive high selectivity of tap water hypochlorous acid sensor. Detection range of0.1-300mM, detection limit of0.03mM, and we have successfully applicated this approach to the tap water in the detection of hypochlorous acid.(2) The study found that quercetin is a kind of polyhydroxy flavone with good dispersancy, fluorescent Si-unmarked dots of fluorescence quenching effects. Explore quercetin in Si-dots and build the mechanism of fluorescence quenching of high sensitive quercetin biosensor. Detection range is from0.1to300μM (R2=0.992) and the fluorescence intensity and quercetin is linearly related to concentration with the detection limit of0.015μM. Therefor, we have successfully applicated this approach to the analysis of quercetin in capsules.(3) In this paper, we discovered that label-free Silicon dots (Si-dots) possess intrinsic peroxidase-like activity. The as-prepared Si-dots exhibit several advantages such as good stability, monodispersion and high catalytic efficiency to the oxidation of3,3’,5,5’-tetramethylbenzidine (TMB), a substrate of horseradish peroxidase, by hydrogen peroxide (H2O2). The peroxidase-like activity and robustness of Si-dots were studied in different environments, such as temperature, H2O2 concentration and pH. Steady-state kinetic and peroxidase-like catalytic mechanism of peroxidase activity of Si-dots was also investigated. The results showed that Si-dots have high catalytic activity and good robustness. Based on the catalysis of glucose oxidase (GOx) to glucose oxidation and Si-dots toward the oxidation of3,3’,5,5’-tetramethylbenzidine (TMB), a simple, inexpensive, highly sensitive and selective glucose colorimetric detection method for glucose detection was developed. Under the optimal conditions, a linear response with glucose concentration ranging from0.017μM to200μM was obtained. The detection limit reached as low as5nM. Moreover, the cost-effective method was successfully applied to the determination of glucose in serum sample.