LAUSR

A novel biosensor for ultra-trace mRNA sensing was constructed based on isothermal circular strand-replacement polymerization (CSRP) to amplify the electrochmeiluminescence (ECL) signal by combining quantum dots (CdTe) as luminophore. After the hairpin-like capture DNA was opened by hybridization with target mRNA, the additive primer (DNA1) was able to get access to its complementary sequence which is partially belong to the stem part and triggered a polymerization of DNA strand, leading to the release of target mRNA and another polymerization cycle. The remaining sequence of the stem part continued to hybridize with QDs labeled DNA, accomplishing ECL signal amplification. Target mRNA could be specifically assayed with a linear relationship between the signal intensity and the logarithm of concentrations of target DNA in the range of 1.0×10−14∼5.0×10−10 M, with a low detection limit of 1.4×10−15 M. The signal could discriminate perfect matched target mRNA from 1-base mismatch sequence. This proposed ECL biosensor exhibited an efficient performance in serum sample, opening new opportunities for genetic target analysis in diagnostic and clinic biomedical fields.