title: Aptameric molecular switch for cascade signal amplification.
abstract: BACKGROUND
  High sensitivity of analysis is constantly in demand in biomedical research and clinical diagnosis. In recent years aptamer-based analytical methods have been developed for protein detection. We developed a cascade signal amplification strategy based on molecular switches and aptamers to improve protein detection.
  
  
  METHODS
  Our cascade signal amplification strategy based on molecular switches and aptamers consisted of 2 steps, including the recognition and the triggering of a polymerase reaction. The procedure was designed to simplify the analysis by detecting trace amounts of target isothermally, in real time, and in a homogeneous solution. We applied this method to measure thrombin in human serum samples.
  
  
  RESULTS
  This cascade signal amplification strategy exhibited a linear response in thrombin concentration from 0.3 to 10 nmol/L, with a detection limit of 1.7 × 10(-10) mol/L within 60 min. Results of the analysis of thrombin in human serum diluted 1:1 appeared to be linear, as was observed in buffer, in the tested concentration range of 0.3-10 nmol/L.
  
  
  CONCLUSIONS
  The aptameric sensor provides promising potential for detecting and screening trace concentrations of biomarkers in complex matrices for clinical applications.
authors.affiliation: State Key Laboratory Base of Eco-Chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, P. R. China.
authors.forename: Cuiping
authors.initials: C
authors.lastname: Ma
authors.forename: Chunhui
authors.initials: C
authors.lastname: Zhao
authors.forename: Yujie
authors.initials: Y
authors.lastname: Ge
authors.forename: Chao
authors.initials: C
authors.lastname: Shi
mesh_terms: D052157:Aptamers, Nucleotide; D015374:Biosensing Techniques; D005453:Fluorescence; D006801:Humans; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D044967:Serum; D013696:Temperature; D013917:Thrombin / Q000032:analysis* / Q000235:genetics
chemical_list: D052157:Aptamers, Nucleotide; D013917:Thrombin