Infections caused by antibiotic resistant bacteria pose a multifaceted threat to global health. Sensors targeting key virulence factors such as siderophores, offer an unconventional yet selective detection approach for determination of bacterial virulence and pathogenicity, as siderophore production rate reflects both traits. This study presents a graphene oxide-Fe 3 O 4 composite based electrochemical sensor for detection of enterobactin, an archetypal siderophore from E. coli. The developed sensor exhibited a tenfold increase in current compared to bare screen-printed carbon electrode and achieved a detection limit of 0.1μM for standard enterobactin, with a linear detection range of 0.1-100 μM and an R 2 value of 0.99. Siderophore production was confirmed, quantified and demonstrated as a marker for metabolically active bacteria in iron-limited environments with a response time of four minutes. This study establishes a label-free, biorecognition element free, precise detection of siderophores in real-world samples, such as urine, serum and river water (0.1-50 μM), (1-100 μM) and (0.5-10 μM) respectively with an error of less than 9% for five months of use. This sensor enables the identification of virulence activation in metabolically active E. coli in iron restricted environments as an indicator of possible pathogenicity. Independently it serves as an indicator of iron deficiency in physiological specimen. It may also be utilized to access possible faecal contamination in environmental aqueous specimen. The value proposition of this sensor is as a preliminary screening tool of clinicians in primary healthcare setups of resource constrained settings as an indicator of possible E. coli infections. • Graphene oxide-Fe 3 O 4 sensor detects siderophores from gram-negative bacteria. • GO-Fe 3 O 4 nanocomposite modified screen printed carbon electrode improves electron transfer efficiency. • The sensor demonstrated good recovery rates and selective detection of enterobactin in mixed sample matrices. • Proof-of-concept detects siderophores in cultures and real-world samples
Sreelakshmi et al. (Wed,) studied this question.