An electrochemical biosensor with homogeneous dual amplification strategy for sensitive analysis of Pb2+

Abstract

Herein, a homogeneous double amplified electrochemical biosensing system was designed on the basis of rolling circle amplification (RCA) and DNAzyme-assisted Pb2+ recycling amplification with the assistance of the signal molecule methylene blue (MB), which was used for highly sensitive analysis of Pb2+. In comparison with the conventional electrochemical biosensor, the homogeneous strategy adopted in this work can avoid the complex electrode modification and immobilization processes, and address the issues of the large steric hindrance and the restricted probe freedom on the sensing interface, thus achieving high recognition efficiency between recognition unit and target molecule as well as excellent detection performance of biosensor. In addition, the double amplified method assembling RCA and DNAzyme-assisted Pb2+ recycling amplification can convert a handful of target Pb2+ into abundant signal molecule MB, which would lead to the double amplification of output signal and the significantly enhanced detection sensitivity. Taking advantages of homogeneous dual amplification strategy, the constructed electrochemical biosensor for Pb2+ analysis emerged a good linear range of 50 fM to 500 nM and a detection limit of 16.7 fM with significant selectivity and desirable stability. Impressively, the result presented herein comprise a valuable reference for establishing homogeneous multiple amplification model and constructing innovative biosensing system for sensitive detection of heavy metal ions.