Search

The temperature-sensitive liposomes were constructed by poly (2-ethylacrylic acid) (PEAA) alkylamide derivatives that were synthesized for partially modification of carboxylic groups. The thermal characteristics of liposomes were investigated by using fluorescent indicator, particle size device and fluorescence spectrophotometer system. The results showed that the liposome made of fatty amine-modified poly(2-ethylacrylate) had a marked thermal sensitive release of drugs, which is correlated with the structure of molecular of polymer and the initial ratio of composition of phospholipid. The PEAA-associated-liposomes were also shown pH-sensitive drug release under acidic condition. The poly (2-ethylacrylate) for the preparation of medium-induced thermal liposomes in vitro experiments showed a good thermal characteristics and the methods of preparing temperature-sensitive liposomes were convenient and stability.

The reaction conditions for the determination of bovine serum albumin (BSA) using o-hydroxyphenylfluorone (o-HPF) as fluorescence probe reagent were studied. In the B-R medium at pH 7.90, o-HPF could react with BSA, producing a stable complex compound which resulted in fluorescent quenching of this binary system. The quantitative assay was carried out based on the relation between the degree of fluorescent quenching and the additional amount of BSA. The method has advantages of good selectivity, stability and simplicity. The linear range of o-HPF fluorescence spectrophotometric method was 1.32-18.54 microg x mL(-1). Moreover, the mechanism of the reaction BSA and o-HPF was discussed, and the quenching constant, and the ther modynamics constant of the fluorescence effects were calculated. The results showed that the nonconvalent binding forces were the binding force between o-HPF and BSA, and the quenching of BSA to o-HPF was probably a single static quenching process.

The fluorescence characteristics of the interaction between DNA and two halogen fluoresceins, tetrabromofluorescein (TBF) and tetrachlorotetrabromofluorescein (TTF), were studied. The result showed that for TBF, lamda ex/ lamda em were 518 nm/540 nm, and for TTF, they were 540 nm/560 nm. The intensity of fluorescence of TBF and TTF changed in the presence of DNA. The fluorescence quenching studies indicated that TBF binds to DNA in the groove and the polarization experiments showed that TBF is intercalated into the DNA base pairs. So the comprehensive interaction mode of TBF with DNA may be that TTF is intercalated into DNA base pairs and binds to DNA in the groove. Both the fluorescence quenching studies and the polarization experiments indicated that TTF is intercalated into the DNA base pairs. It was also found that ionic strength could affect the interaction of TBF/TTF and DNA. The binding constants K are 1 x 10(6) L x mol(-1) and 2 x 10(6) L x mol(-1), and the binding site numbers n are 0.62 and 0.16 for TBF and TTF, respectively.