Entropy-Driven Molecular Switch And Signal Amplification For Homogeneous Snps Detection

After the Human Genome Project was completed in 2003, many researches have played more attention on identifying individual variations in the human genome because gene polymorphisms (SNPs) can have a major impact on how human respond to diseases. The development of individualized medicine is becoming more important. Thus, the SNPs of patients and other mutations correlated to diseases and disease predisposition need to be rapidly detected.Homogeneous assays offer the potential to detect in real time, and are able to reduce contamination and the need of multiple washing steps. A strategy of rapidly and sensitively detecting SNP in homogeneous solution was presented based on entropy-driven molecular switch and isothermal strand- displacement polymerase amplification reaction without addition of exogenous primers. The strategy showed good sensitivity with detection limit of 1.85×10-10 M, which could directly be used to detect genomic DNA. The change of fluorescence intensity revealed a good linear relationship with the logarithm of mutant DNA concentration ranging from 4.0×10–10 to 2.0×10–8 M. And the presented approach had the high specificity for detecting a trace mutation among abundant wild-type DNA owing to the high fidelity of T4 DNA ligase. The mutant DNA could even be detected in 10 nM genomic DNA when its concentration was about 0.3 nM. Especially, the conformational change of molecular switch owing to the hybridization with target made 3′-end of molecular switch as primer to originate polymerization reaction without addition of exogenous primers. This approach is very useful for quantitative point mutation and we believe it will be extensively applied in the fields of basic and clinical research, and diagnostics.