Fluorescence Sensor Based On Polyoxometalate For Rapid And Sensitive Detection Of Artemisinin

Malaria,which is a parasitic disease caused by five different species of Plasmodium,is one of the most important public health problems.According to a 2018 report by the World Health Organization,there are 2.28 billion malaria cases in the world,93%of which occur in Africa.Children（under 5 years of age）are the most vulnerable to malaria,accounting for 67%of the world’s deaths.The great discovery of Chinese pharmacist Tu Youyou provided the world with the most effective antimalarial drug-artemisinin so far.At the same time,it was also found that artemisinin not only has antimalarial effects,but also has a wide range of applications in anti-tumor,immune system regulation and anti-virus fields.Therefore,as the demand for artemisinin-related drugs continues to increase,efficient and accurate detection of artemisinin is of great significance to clinical efficacy monitoring and drug development.In this thesis,polyoxometalates（POMs）are used as catalysts,and thiamine hydrochloride(V_b1)is used as a fluorescent probe to establish a fast and sensitive analysis method to detect the content of artemisinin in human plasma and leaves of Artemisia annua.The main research work of this thesis is as follows:1.A new system to detect artemisinin with polyoxometalates（POMs）as catalysts and thiamine hydrochloride as fluorescent probe was developed.Various spectroscopic techniques,including Fourier transform infrared spectroscopy（FTIR）,ultraviolet visible spectroscopy（UV-vis）and X-ray powder diffraction（XRD）,are utilized to characterize the synthesized POMs.The catalytic performance of POMs,vanadomolybdophosphoric heteropoly acid(H₅PMo₁₀V₂O₄₀,PMoV₂)and tungstophosphoric heteropoly acid(Na₅PW₁₁O₃₉Cu,PW₁₁Cu),were investigated.It was indicated that the POMs exhibit peroxidase-like activity,which efficiently catalyze the artemisinin/thiamine reaction to produce fluorescent product thiochrome.With the usage of the POMs as the catalyst in combination with fluorescent probes,we propose a method for highly sensitive and rapid determination of artemisinin.When PMoV₂ and PW₁₁Cu are used as catalysts,the linear ranges are1.0×10^-6-1.0×10^-1 m M and 5.0×10^-6-9.0×10^-1 m M,and the detection limits are as low as 0.5 n M and 1 n M,respectively.The method is successfully applied to determine artemisinin in human plasma and Artemisia annua.leaves with good accuracy.2.A capillary fluorescence chemical sensor based on POMs was proposed by self-assembly method and applied to the rapid and sensitive detection of artemisinin.Firstly,the negatively charged silicon hydroxylated capillary was combined with the positively charged Polydiallyldimethylammonium chloride（PDDA）by electrostatic adsorption,and then the negatively charged POMs were loaded to make the microchannel sensor.The sample solution was injected into the sensor spontaneously by siphon action,and the fluorescence signal was collected and detected by the laser-induced fluorescence detection device built in the laboratory.The linear range of artemisinin was 0.15-9μM（PMoV₂）and 0.5-13μM(PW₁₁Cu),respectively.The detection limits were 0.03μm（PMoV₂）and 0.15μm(PW₁₁Cu),respectively.The prepared capillary fluorescent chemical sensor has the advantages of low cost,low consumption,rapid analysis,less sample consumption and convenient operation.In addition,the capillary sensor is small in size and easy to handle,which is beneficial to the instrument miniaturization.It has been successfully applied for the determination of artemisinin in human plasma and commonly used antimalarial drugs.