3D origami electrochemical device for sensitive Pb2+ testing based on DNA functionalized iron-porphyrinic metal-organic framework

• A highly sensitive electrochemical biosensor for detection of Pb2+ based on Au-PWE as sensor platform and DNA functionalized (Fe-P)n-MOF as signal probes.
• In the presence of Pb2+, GR could be specifically cleaved at the ribonucleotide site, so that the biosensor had a good selectivity.
• The resulting µ-PAD EC biosensor, with simple, low cost, ultrahigh sensitivity and satisfactory stability, could be detection of Pb2+ in environmental and biological samples.

A highly sensitive electrochemical (EC) biosensor combined with a 3D origami device for detection of Pb2+was developed based on novel Au nanoparticles modified paper working electrode (Au-PWE) as sensor platform and DNA functionalized iron-porphyrinic metal-organic framework ((Fe-P)n-MOF-Au-GR) hybrids as signal probes. In the presence of Pb2+, GR could be specifically cleaved at the ribonucleotide (rA) site, which produced the short (Fe-P)n-MOF-linked oligonucleotide fragment to hybridize with hairpin DNA immobilized on the surface of Au-PWE. Because of the mimic peroxidase property of (Fe-P)n-MOF, enzymatically amplified electrochemical signal was obtained to offer the sensitive detection of Pb2+. In addition, benefiting from the Pb2+ dependent GR, the proposed assay could selectively detect Pb2+ in the presence of other metal ions. This method showed a good linear relationship between the current response and the Pb2+ concentration ranging from 0.03 to 1000 nmol L−1 with a detection limit of 0.02 nmol L−1. The Au-PWE based electrochemical sensor along with the (Fe-P)n-MOF-Au-GR probe exhibited the advantages of low-cost, simple fabrication, high sensitivity and selectivity, providing potential application of real-time Pb2+ detection both in environmental and biological samples.