Development of an advanced electrochemical biosensing platform for E. coli using hybrid metal-organic framework/polyaniline composite

Because of numerous merits (e.g., the possibility of their synthesis in 1-D, 2-D, and 3-D forms, large surface-to-volume ratio, and flexible framework functionality), metal-organic frameworks (MOFs) are envisaged as excellent media for the development of biosensors for diverse analytes present in environmental media. The present research work, for the first time, reports the development of a Cu-MOF based electrochemical biosensor for highly sensitive detection of E. coli bacteria. In order to realize an MOF-based electrochemically active platform, Cu₃(BTC)₂ (BTC = 1,3,5-benzenetricarboxylic acid) was mixed with polyaniline (PANI). The spectroscopic/morphological characterizations of the resulting composite were established with the aid of FT-IR, UV-visible spectroscopy, X-ray diffraction, electron microscopy, and surface area analysis. The thin films of Cu₃(BTC)₂-PANI, on an indium-tin oxide (ITO) substrate, were bio-interfaced with anti-E. coli antibodies for use as a novel biosensing electrode. Based on the electrochemical impedance spectroscopy (EIS) technique of signal measurement, the above sensor exhibited high sensitivity to detect very low concentrations of E. coli (2cfu/mL) in a short response time (~2 min) and was also selective in the presence of other non-specific bacteria. As a novel highlight of the research, this new MOF/PANI based detection platform for E. coli has shown improved performance than many of the previously reported electrochemical biosensors.