Label-free DNA sensor based on fluorescent cationic polythiophene for the sensitive detection of hepatitis B virus oligonucleotides.

Water-soluble fluorescent conjugated polymers can be used as an optical platform in highly sensitive DNA sensors. Here we report a simple label-free DNA sensor using poly(3-alkoxy-4-methylthiophene) to recognize and detect different oligonucleotide targets related to the YMDD gene mutation of hepatitis B virus. The concentration of surfactant Triton X-100, NaCl, the oligonucleotide capture probe and the oligonucleotide hybridization conditions have a great impact on fluorescence intensity. Under the optimum conditions, two types of oligonucleotide targets involving YMDD gene mutation of hepatitis B virus were successfully recognized. Moreover, there was a linear relationship between fluorescence intensity and the concentration of oligonucleotide target. The detection limit of the wild-type hepatitis B virus target is 88 pmol L(-1).