Hierarchical cystine flower based electrochemical genosensor for detection of Escherichia coli O157:H7

Abstract

This work reports on a facile and reproducible approach to synthesize novel organic flowers of cystine (CysFls) with high uniformity. These 3D flower-like structures have a purely hierarchical arrangement, wherein each petal is composed of several cystine molecules with an average size of 50 μM, as determined by transmission electron microscopy. The CysFls were self-assembled onto a gold electrode and were utilized as matrices for the covalent immobilization of an Escherichia coli O157:H7 (E. coli) specific probe oligonucleotide that was identified from the 16s rRNA coding region of the E. coli genome. This fabricated CysFl platform sought to provide improved fundamental characteristics to electrode interface in terms of electro-active surface area and diffusion coefficient. Electrochemical impedance spectroscopy revealed that this genosensor exhibits a linear response to complementary DNA in the concentration range of 10⁻⁶ to 10⁻¹⁵ M with a detection limit of 1 × 10⁻¹⁵ M. Under optimal conditions, this genosensor was found to retain about 88% of its initial activity after being used for 6 times.