Recently, the research paper of associate professor Zhao Yongxi's research group in Biological Information Research Center of the School of Life Science and Technology entitled "Polymerase/Nicking Enzyme Synergetic Isothermal Quadratic DNA Machine and Its Application for One-Step Amplified Biosensing of Lead Ion (II) and DNA Methyltransferase" was published online on NPG Asia Materials (IF=9.902), which is under Nature Publishing Group. The work was done in cooperation with researcher Fan Chunhai from Shanghai Applied Physics Research Institute of the Chinese Academy of Sciences. The key laboratory of the Ministry of Education the Biological Medicine Information Engineering Laboratory of the School of Life Science and Technology is the first finishing unit and first communication unit of the paper. Doctoral student Chen Feng and graduate student Zhang Qing from the School of Life Science and Technology took part in the research task.

DNA molecular machine is a kind of supermolecule nanostructure based on "watson-crick" base pair. It can identify target molecules peculiarly and realize the function of simulating macro-machines by changing the structure of DNA and it is widely applied in the fields like environment survey, moleculardiagnosis and gene therapy. However, the traditional DNA molecular machine is difficult to designwithcomplex system and low signal response. The polymerase-nicking enzyme synergetic isothermal quadratic DNA molecular machine (ESQM) reported by the paper integrates chain displacement amplification module with nicking enzyme amplification module cleverly by a specially designed hairpin structure and realizes efficient and quick signal amplification without adding system complexity. DNA zyme and ESQM relied on by conjugated metal ion have been successfully applied to ultrasensitive and high specificity detectionof lead ion in the water in Chanhe river and Bahe river and potable water.The detection result is in line with the analysis result of ICP-MS. The molecular machine is in common use and can be applied to the activation and medicine inhibition role analysis of the potential mark of tumors DNA methyltransferase after it is modified simply. The research work not only provided an effective survey means for the current grim heavy metal pollution, it can also be applied to tobacco industry to overcome the problems of the traditional heavy metal detection of tobacco like it is expensive and the sensitivity is low. It can be applied to the early diagnosis of tumors and medicine screening hopefully.

In addition, another paper of the research group on tumor mark microRNA was published online on the authoritative magazine in the field of analytical chemistry Analytical Chemistry (IF=5.825) recently. How to peculiarly distinguish thehomologous sequence of microRNAfamily has always been the important and difficult task of microRNA research.The paper designed three-way nucleic acid hybrid nanostructure triggered by target microRNA peculiarity, which can significantly strengthen target identification selection. Meanwhile, it can cleverly avoid the difficulty that the traditional method can't identify 3'end decoration microRNA like plant microRNA without using microRNA as the primer. The ultrasensitive and high specificity detection of tumor cell microRNA can be realized finally in connection with the efficient signal amplification. The result is in line with the standard method real-time quantification PCR , which provides a powerful tool for the early diagnosis and prognosis survey.

The research group also structured a new colorimetricsensor based on DNAzyme structure, which can analyze the activation and inhabitation roles of DNA methyltransferase by naked eyes without large detection machines. The relevant result has been published on the world-famous magazine Biosensors and Bioelectronics (IF=6.451).

The above research work was funded by the cooperation project of the Shaanxi Province Company of China National Tobacco Corporation and the National Natural Science Fund.

The research group of associate professor Zhao Yongxi has published 7 papers on the international authoritative academic periodicals (IF>5) in recent three years and conducts a series of research work on the relevant marks like microRNA, telomere enzyme andmethyltransferase, environment pollutants like lead ion and mercury ion and important biological micromolecules like ATP and NAD+.