Tetra substituted amino aluminum phthalocyanine (TAAlPc) has been synthesized and used for the first time as a new red region fluorescent substrate for the determination of hydrogen peroxide catalyzed by peroxidase or mimetic peroxidase. Under optimum conditions, the calibration graph has a linear range of 0.0-3.0×10 -7 mol/L H 2O 2 with a detection limit of 3.7×10 -9 mol/L. The feasibility of TAAlPc as a new promising red region substrate in practical application has been proven in the determination of H 2O 2 in rainwater.The proposed method can largely minimize the interference that results from background fluorescence or scattering light and has a high analytical sensitivity.
Fluorescence anisotropy was employed for the investigation of the association between AlS 4Pc and BSA. The average binding number of AlS 4Pc to BSA was calculated and the constants of association reaction occurring in the medium of pH 7 0 were shown. The results revealed that the interaction between AlS 4Pc and BSA was strong, which implied that AlS 4Pc may be stored and transferred by serum albumin. The merits of the method used were also pointed out.
Poly( N isopropylacrylamide methylacrylic acid)[P(NIP co MAA)], a linear water soluble pH precipitating synthetic polymer, was used as a novel separating carrier for the reactants in immunoassay. The P(NIP co MAA) precipitates out of water below a critical pH 5.6 at 37 ℃, and redissolved when the solution pH is above 6.1. This characteristic of the P(NIP co MAA) made it possible to carry out the immunochemical steps of the assay in true solution and then to quickly separate the resulting procucts from the reaction mixtures. The above approach was applied to an assay for the sandwich immunoassay of hepatitis B surface antigen(HBsAg). Sensitivity of this method was close to that of traditional ELISA using same reactants. However, the assay was much faster(assay time decreased from 100—120 min to 45 min). This method has been applied to the determination of the HBsAg levels in human blood serum with satisfactory results. This general technique may also be used for a wide variety of separation processes in addition to immunoassay, in which a specific component is to be isolated for analysis, recovery, or disposal. [WT5HZ]
The fluorescence behavior of two near-infrared (NIR) chromophores with linear alkyl chains of different lengths, 2-[4'chloro-7'(3'ethyl-2'benzothiazolinylidene)-3',5'-(1''',3'''-propanediyl)-1',3',5'-heptantriene-1'-yl]-3-ethylbenzo- thiazolium iodide (Probe I) and 2-[4'chloro-7'(3'hexadecyl-2'benzothiazolinylidene)-3',5'-(1''',3'''-propanediyl)- 1',3',5'-heptantriene-1'-yl]-3-ethylbenzothiazolium iodide (Probe II), in aqueous solution containing different con-centrations of surfactants was studied. The fluorescence of the probe with a short chain (probe I) was completely quenched in water and aqueous solution containing a low concentration (below the critical micelle concentration, CMC) of surfactant Triton X-100. However, the fluorescence reappeared and reached maximum rapidly once the concentration of the surfactant approached the CMC. The probe with a long chain (probe II) displayed a similar fluorescence behavior but more dramatically fluorescent recovery in Triton X-100 system, which gave a direct in-dication for the micelle forming process and provided a simple method for the determination of the critical micelle concentration of the surfactant. The CMC values determined by this method were in good agreement with those ob-tained by other techniques. The fluorescence behavior of the two probes in other surfactant systems was also inves-tigated.
