In preparing DNA fluorescence capillary biosensor(DNA-FCB),capillary was used as carrier to immobilize DNA and complementary target DNA was sucked into the capillary for the hybridization to form spiral dual chain DNA in which berberine was embedded as the fluorescence labelling substance.By measuring the fluorescence intensity with a fluorospectrophotometer,the target DNA was detected qualitatively and quantitatively.Optimum conditions for the determination were found as follows: ① volume of sample solution taken: 12 μL;② range of linearity and linear regression equation: 2-10 μmol·L-1 of target DNA,y=9.52 x+9.22(r=0.991 2);③ detection limit: 1.16 μmol·L-1 of target DNA.The method of determination of target DNA with this biosensor was proved to be simple and convenient in operation,low in consumption of reagents and in cost for determination,as well as profitable to environmental protection.

The correlation of the fluorescence intensity of berberine hydrochloride(BB) with double-stranded DNA(dsDNA) was examined and the operation conditions for BB in agarose gels electrophoresis were optimized.The staining effect of BB was imaged and compared with that of ethidium bromide(EB).The results showed that the fluorescence intensity of BB was enhanced significantly by dsDNA and the increased intensity was proportional to the concentration of dsDNA.A nontoxic and simple staining method with fluorochrome BB for the detection of DNA in agarose gels was thus developed.The method can detect as little as 100 bp per band of DNA(10 ng) stained by 10 mg/L BB in gels.For small fragment of dsDNA,the sensitivity of BB was a bit lower than that of EB under the same experimental conditions,since BB was positively charged in alkaline solution leading to the decrease of DNA relative mobility.