Polyoxometalates as catalysts for fluorescence amplification in rapid and sensitive detection of artemisinin

The combination therapy based on artemisinin is the most effective method to treat malaria. Sensitive, rapid and accurate detection of artemisinin is very important to monitor clinical pharmaceutical effect as well as the drug quality control. In this work, catalytic performance of polyoxometalates (POMs), vanadomolybdophosphoric heteropoly acid (H₅PMo₁₀V₂O₄₀, PMoV₂) and tungstophosphoric heteropoly acid (Na₅PW₁₁O₃₉Cu, PW₁₁Cu), are investigated. It is 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 are 1.0 × 10^-6-1.0 × 10^-1 mM and 5.0 × 10^-6-9.0 × 10^-1 mM, and the detection limits are as low as 0.5 nM and 1 nM, respectively. The method is successfully applied to determine artemisinin in human plasma and Artemisia annua. L leaves with good accuracy.