A polyethyleneimine reduced graphene oxide/gold nanocubes based electrochemical aptasensor for chloramphenicol detection using single-stranded DNA-binding protein.

Developing a simple and reliable method for the detection of the highly concerning antibiotic, Chloramphenicol (CAP), is of great importance to food safety monitoring. In this study, the authors take the advantages of polyethyleneimine-functionalized reduced graphene oxide and gold nanocubs (PEI-rGO/AuNCs) composite as electrode modification material to develop an electrochemical aptasensor for the detection of CAP using single-stranded DNA-binding protein. PEI-rGO/AuNCs warrants good electrical conductivity and a high surface-to-volume ratio to achieve the purpose of signal amplification. The CAP-binding aptamers were immobilized on the PEI-rGO/AuNCs modified gold electrode via Au-S affinity. Based on the property that single-stranded DNA-binding protein (SSB) can bind to free single-stranded oligonucleotides without binding to folded oligonucleotides, in the presence of CAP, only a small number of SSB will be immobilized on the aptasensor surface results in a larger peak current, which is typically measured at 0.176 V (vs. Ag/AgCl). The assay has a linear response in the 5 pmol·L−1 to 1 μmol·L−1 concentration range, with a 2.08 pmol·L−1 detection limit. Moreover, the proposed method has been applied to detect CAP in spiked chicken samples with satisfactory results. Unlabelled Image • Edges and vertices of AuNCs have more available reaction sites. • PEI-rGO/AuNCs can significantly improve aptasensor detection performance. • SSB provides a simple signal amplification aptasensor strategy. • Aptamer-based recognition element imparts sensor specificity. [ABSTRACT FROM AUTHOR]