Cascade primer exchange reaction-based amplification strategy for sensitive and portable detection of amyloid ß oligomer using personal glucose meters.

Amyloid ß oligomer (AßO) is an important biomarker for Almerzheimer's disease (AD) early diagnosis. In present study, cascade primer exchange reaction (PER) based amplification strategy was proposed for sensitive and portable detection of AßO using personal glucose meters (PGM). Two PER processes were employed here. In the primary PER, the hairpin template 1 (HT1) was designed with a primer binding domain, a primer extending domain and a blocking extending domain. The primers were designed to be modified on magbeads surface. Initially, the primer binding domain in HT1 was locked by AßO aptamer. When target AßO was present, aptamer bound with AßO and dissociated from HT1 to initiate the primary PER. The products acted as the primer of the secondary PER to hybridize with another hairpin template 2 (HT2), initiating the secondary PER and producing numerous ssDNA with repeated DNA-invertase binding sites. After binding with DNA-invertase, the obtained conjugates were magnetically separation to catalyze the conversion of sucrose to glucose, which were detected by a PGM. The strategy achieved a limit of detection of 0.22 pM with a linear ranged from 1 pM to 250 pM. Satisfactory reproducibility results were obtained in actual samples. This strategy provided a superior tool for sensitive and convenient detection of AßO, and showing a great potential in the early diagnosis of AD.

Digital quantitative detection of serum circulating miRNAs using dual-enhanced magnetobiosensors based on cascaded nucleic acid circuits.

The tough challenges for the convenient and quantitative determination of circulating miRNAs (cmiRNAs) in the peripheral blood are low abundance, high interference and lack of direct digital readout. Here, we developed dual-enhanced magnetobiosensors based on cascaded nucleic acid circuits, which integrate catalyzed hairpin assembly (CHA) with the hybridization chain reaction (HCR), for sensitive, portable and digital quantitative detection of circulating miRNAs in serum by a personal glucose meter (PGM).