We report an improved strategy for conjugated polymer-based optical DNA detection with stem-loop structured DNA probes.The high sensitivity of conjugated polymer-based biosensors arises from light harvesting by the conjugated polymer and the related amplified fluorescent signal transduction either through quenching or through Fǒrster energy transfer) In our previous publication,we demonstrated that the coupling of magnetic particles to conjugated polymers significantly improves the selectivity of this class of DNA sensors.Here we further improved the selectivity by introducing both stem-loop structured capture probe and competition probe.We demonstrated further that this improved magnetically assisted DNA sensor can conveniently identify even a single-nucleotide mismatch in the target sequence.
Jiang LiXingfen LiuHui XuShiping SongYun ZhaoChunhai Fan
Nanoparticle PCR is a novel method to optimize DNA amplification. It performs well in improving specificity, enhancing sensitivity and speed. Several mechanisms were proposed in previous studies: one was based on the interaction between gold nanoparticles (AuNPs) and DNA while the other was attributed to the heat transfer property of AuNPs. In this paper, we propose that the interaction between AuNPs and DNA polymerase can significantly influence PCR. First, the addition of DNA polymerase can eliminate the inhibitory effects of excess AuNPs. Second, the addition of AuNPs will increase yield of the desired PCR product and make the optimum concentration of DNA polymerase move to higher value. Third, while excess polymerase might inhibit amplification efficiency, AuNPs can reverse this process and the yield of PCR amplification. Based on these results we propose a possible mechanism that AuNPs might modulate the activity of polymerase and improve PCR amplification.
MI LiJuanZHU HongPingZHANG XiaoDongHU JunFAN ChunHai
