Quantum Dot Tungsten Oxide Mimics Peroxidase

In recent years, the appearance of nano material artificial analogy peroxidase can effectively overcome the above shortcomings of natural enzyme, showing strong catalytic activity and specificity. The quantum size effect, small size effect, interface effect, surface effect and macro quantum tunneling effect of nano tungsten oxide make it have more advantages in optical, magnetic, catalytic and chemical activities. Based on the quantum effect, quantum dots have a wide range of applications in solar cells, light-emitting devices, optical biomarkers and other fields.

The simulated peroxidase process of quantum dot tungsten oxide material is as follows:

(I) Preparation of tungsten oxide quantum dots
Weigh 0.03g of tungsten sulfide, add 200ml of 65 ℃ secondary distilled water, and put it into ultrasonic cleaner (Power: 400W) for 15-24 hours. The filter cake was obtained by filtration in a sand core funnel with a pore diameter of 0.22 um, and then the collected filter cake was suspended in 30ml of secondary distilled water. The above solution was placed in a polytetrafluoroethylene autoclave, heated at 200 ℃ for 12-18 hours, then cooled to room temperature to obtain hydrothermal products. The obtained hydrothermal products are filtered through a sand core funnel with a pore diameter of 0.22 um, and the filtrate is collected to obtain the solution of tungsten oxide quantum dots. The solid powder of tungsten oxide quantum dots can be obtained by suspension evaporation, ethanol dispersion, centrifugation (the rotating speed of the centrifuge is 16000r / min, the time is 30min), vacuum drying (the temperature is 50 ℃ ~ 60 ℃, the drying time is 8h ~ 12h).

(II)  Simulation of peroxidase activity in tungsten oxide quantum dots
1. The peroxidase activity of 3,3 ', 5,5' - tetramethylbenzidine hydrochloric acid was verified and compared. Hydrogen peroxide, 3,3 ', 5,5' - tetramethylbenzidine hydrochloric acid and tungsten oxide quantum dots were added into the buffer successively. After mixing, the color change was observed or the absorbance value at 652nm wavelength was measured in different time of temperature bath. Compare the activity of peroxidase according to the color of the solution or by measuring the absorbance value.

2.The green substrate was produced by 2,2 '- diazo bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt of peroxidase substrate catalyzed by tungsten oxide quantum dots, and its peroxidase activity was verified and compared. Hydrogen peroxide, 2,2 '- diazo bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt and tungsten oxide quantum dots were added into the buffer successively. After mixing, the color was observed in a warm bath for a certain time.

3.The activity of peroxidase was verified and compared by using tungsten oxide quantum dots to catalyze the formation of yellow substrate by o-phenylenediamine. Hydrogen peroxide, o-phenylenediamine and tungsten oxide quantum dots were added into the buffer successively. After mixing, the color of the QDs was observed in a warm bath for a certain time.

The obtained tungsten oxide quantum dot material has the advantages of simple preparation process, environmental protection, low cost, ideal effect can be achieved by using a very small amount, and the cost can be greatly reduced compared with the natural enzyme.

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