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Fluorescence decrease ratio was applied to determine of artemisinin (qinghaosu, QHS) based on the catalytic effect of hemoglobin (Hb) using tetraethyldiaminoxanthenyl chloride (Pryonine B, PB) as monitor in this work. Experimental result show that the catalytic characteristics of Hb for QHS, being expressed as Michaelis-Menten parameters,Km,Vmax, andKcat are 2.8×10−5 mol ·L−1, 4.2×106 mol · L−1 · s−1 and 280 s−1, respectively. Like hemin, enzymatic bioactivities of Hb is inhibited by both deactivated agents and high temperature where-as enhanced by ethanol. With the catalytic action of Hb, quantitative method of QHS can be established based on the fluorescence decrease of PB and linear relationship between the fluorescence decrease ratioF0/F and the concentration of QHS is in the range of (0.0−1.1)×105 mol · L−1 with detection limit (3σ) being 7.2 ×10−9 mol ·L−1. The concentration of QHS in the media of plasma or urine was detected using this method.

Fluorescence decrease ratio (F0/F) was applied to determination of artemisinin (qinghaosu, QHS) based on the catalytic effect of tyrosinase using tetraethyldiaminoxanthenyl chloride (pyronine B, PB) as monitor. A catalyst used commonly in the decomposition of QHS, tyrosinase, exhibited higher binding activity than hemin, which was expressed as Michaelis-Menten parameters, km, vmax, and kcat respectively. Interaction of QHS with tyrosinase was inhibited in the presence of deactivating agents at high temperature whereas enhanced by ethanol. Under optimal conditions, a concentration of 1.4×10-7-8.4×10-7 mol·L-1of QHS could be determined on the basis of fluorescence decrease ratio of PB, with a detection limit 3σ of 2.6×10-9 mol·L-1. The proposed method was applied to detection of the concentration of QHS in the media of plasma and urine.

Fluorescence quenching of janus green B (JGB) in sodium dodecyl sulfate (SDS) micelle by nucleic acids (DNA) was studied using UV-vis absorption, steady state fluorescence emission methods and lifetime measurements. In the SDS micelle, weak fluorescence of JGB was enhanced, and the maximum emission shifted from 425 to 410 nm. In the presence of DNA, the fluorescence of JGB was quenched. Linear relationships between the fluorescence quenching (F0/F) and concentrations of DNA were observed in the range of 2.4×10−8 to 1.08×10−7 mol·L−1 for calf thymus nucleic acids (ct DNA) and 1.9×10−8 to 3.8×10−8 mol·L−1 for fish sperm nucleic acids (fs DNA) when 2.5×10−5 mol·L−1 JGB was employed. The limit detection were 1.3×10−8 mol·L−1 for ct DNA and 6.4×10−9 mol·L−1 for fs DNA. At high DNA concentration, there was a systematic deviation from the Stern-Volmer equation due to the static and dynamic quenching occurring simultaneously. The proposed method was applied to the determination of the nucleic acids in chicken blood extraction and the analytical results were in good agreement with the UV-method.

β-Cyclodextrin (β-CD) and its cross-linked polymer (β-CDP) were known as the mimetic models. Metalloporphyrin had been widely used in the enzymatic method of analysis and molecular recognition. In present work, it was investigation that supramolecular recognition for halogenated phenols, three crosols, three nitrophenols and three aminophenols, served respectively as the substrate of the mimetic receptor, iron-5, 10, 15, 20-tetrakis (sulforphenyl)-21H, 23H-porphine (FeTPPS) or FeTPPS-β-CDP. Supramolecular complex, FeTPPS-β-CDP with function of mult i-recognition and induced-fit, was a advanced kind of mimetic peroxidase; Methyl phenol or polyphenol was the substitute of chlorophenic acid, while aminophenols and other phenols were suggested not to be utilized to enzymatic assay of H2O2. Being a mimetic enzyme mimicking the space structure of overall proteinase, beaimed by immobilized mimetic enzyme with a large number of β-CD interior cavities, chlorophenol was identified optimal substrate in the system tested.

Enzyme-catalytic fluorescence determination of artemisinin (qinghaosu, QHS) was developed using pyronine B (PB) as substrate of horseradish peroxidase (HRP). The interaction between HRP and QHS was an enzyme-substrate model. The catalytic characteristic of HRP in the oxidation reaction, in which the fluorescence of PB was decreased in the presence of QHS, was studied. The steady-state catalytic rate depended upon enzyme and substrate concentrations, and the Michaelis-Menten parameters K m Vmax and K cat were 8.4×10−5 mol · L−1, 7.4×10−6 mol · L−1v s−1 and 50.23 s−1. The catalytic activity of enzyme was inhibited in the presence of deactivated agents and at high temperature, respectively. Under optimum conditions, linear relationship between fluorescence intensity change (F 0- F) of pyronine B and concentration of QHS was in the range of 1.41×10−7-1.27×10−6 mol · L−1. The detection limit (3σ) was determined to be 2.7×10−8mol· L−1. The proposed method was applied to the concentration determination of QHS in the media of plasma or urine samples.