As an important member of tool enzymes, exonuclease is a kind of hydrolytic enzymes without strict base sequence dependent. In recent years, by taking advantage of different hydrolysis ways of exonuclease and nanotechnology, cycle effect of enzyme digestion, aptamer, non Watson-Crick base pairing system by metal ions, fluorescent nucleic acid probes, electrochemical methods etc. , a series of exonuclease-assisted signal amplification strategies have been developed, which played a very key role in improving the sensitivity of detection methods. Therefore, exonuclease has been widely used in high sensitive detection of nucleic acids, proteins, ions, small molecules and so on. To understand it better and apply it well in the future, the application progress of exonuclease-assisted signal amplification strategies in biochemical analysis has been summarized in this review.

Objective To determine the value of using B-type natriuretic peptide (BNP) and D-dimer in preliminary recognition of cardioembolic stroke patients.Methods A mutilple-center study was conducted in Foshan Hospital of traditional Chinese Medicine (TCM) and its affiliated hospitals from July 2015 to July 2016.In the emergency departments (EDs),emergency physicians prospectively assessed consecutive adult patients with acute cardioembolic stroke and measured plasma BNP by POCT platform on admission,then followed up.Stroke neurologists evaluated patients' functional outcome at hospital discharge and also made discharge diagnosis and stroke etiologic subtypes according to the TOAST criteria.Results In this study,290 acute ischemic stroke patients met the study criteria [mean age (68.41 ± 12.06) years;53.8％ female].Of the enrolled patients,28.3％ were diagnosed with LAA at discharge,17.9％ with CE,42.8％ with SAO,11.0％ with SOE or SUE.And the mean BNP concentration was significantly higher in the CE group than that in other three subtypes (P ＜ 0.001).After adjustment for multiple clinical predictors like gender,age,coronary artery disease,atrial fibrillation and renal function,BNP and D-dimer were associated with CE [BNP OR:1.044 (95％ CI 1.025,1.064),P ＜ 0.001;D-dimer OR:1.511(95％ CI 1.020,2.238),P =0.039,respectively].Conclusion Through POCT technique in the EDs,cardioembolic stroke patients can be differentiated from other TOAST subtypes.BNP with/without D-dimer has good but different corresponding diagnostic performance in preliminary recognition of cardioembolic stroke patients.