Highly Sensitive Optical Detection of Escherichia coli Using Terbium-Based Metal-Organic Framework

Metal-organic frameworks (MOFs) are envisaged as highly useful for the development of biosensors. Herein, for the first time, we report the optical detection of Escherichia coli using a water-dispersible terbium MOF (Tb-BTC; BTC, 1,3,5-benzenetricarboxylic acid). The successful synthesis of Tb-BTC is verified using spectroscopic and morphological techniques like UV-vis, fluorescence and FTIR spectroscopy, X-ray diffraction analysis, and electron microscopy. Tb-BTC has been bio-interfaced with anti-E. coli antibodies and then investigated as a biosensor for E. coli. The biosensor displays detection ability in an analyte concentration range of 1.3 × 10² to 1.3 × 10⁸ cfu/mL with a detection limit of 3 cfu/mL, having a response time of 5 min and a total analysis time of about 20-25 min. The results are also found to be reproducible and specific in the presence of some other interfering bacterial species. As demonstrated, the present sensor provides highly sensitive and specific detection of E. coli in fruit juice sample. To the best of our knowledge, this is the first report to showcase the potential of the MOF-based fluorescent biosensor for the detection of E. coli.