In this paper,we proposed a facile and accurate way for controlling multiplex fluorescent logic gates through changing the exciting and the observing wavelengths.As proof-of-principle,a Pb2+-specific DNAzyme probe and a thymine(T)-rich DNA probe were introduced to a double-stranded(ds-)DNA.The addition style of the two ions served as the four inputs by changing the distance of the three fluorophores,6-carboxyfluorescein(FAM),ALEXA 532(ALEXA)and carboxytetramethylrhodamine(TAMRA),all of which were modified on the dsDNA probe.Compared with the previous methods,the present approach needed neither different inputs nor the change of sequence of the probe to achieve multiplex logic gates.Furthermore,the modularity of the strategy may allow it to be extended to other types of logic gates.
TAO JiaZHENG JingLI JiShanZHAO PengLI JuanPingMA ChengYI MeiYANG RongHua
A new biosensor platform was explored for detection of surfactant based on fluorescence changes from single strand DNA （ssDNA） and single-walled carbon nanotubes （SWNTs）. Thermodynamics assay was performed to value the stability of probe. The affinities of SWNT to five common surfactants （SDS, DBS, Triton X-100, Tween-20 and Tween-80） were investigated by real-time fluorescence method. The effects of Mg^2＋ and pH on the fluorescence intensity of self-assembled quenched sensor were performed. The fluorescent emission spectra were used to measure the responses of self-assembled quenched fluorescent of ssDNA/SWNTs to different concentration surfactant（Triton X-100）. The FAM-DNA wrapped SWNTs probe was stable in a wide temperature range （5 ℃ to 80℃）. The binding strength of surfactants and single-stranded DNA （ssDNA） on SWNTs surfaces was shown as follows： Triton X-100〉DBS〉Tween-20〉Tween-80〉ssDNA〉SDS, and the optimized reaction conditions included pH 7.4 and 10 mmol/L Mg2＋. The fluorescence of FAM-ssDNA wrapped SWNTs was proportionally recovered as a result of adding different concentrations of Triton X- 100, which realizes the quantitative detection of Triton X- 100.
