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Rapid, sensitive, on-site detection of bacteria without a need for sophisticated equipment or skilled personnel is extremely important in clinical settings and rapid response scenarios, as well as in resource-limited settings. Here, we report a novel approach for selective and ultra-sensitive multiplexed detection of Escherichia coli (non-pathogenic or pathogenic) using a lab-on-paper test strip (bioactive paper) based on intracellular enzyme (β-galactosidase (B-GAL) or β-glucuronidase (GUS)) activity. The test strip is composed of a paper support (0.5 × 8 cm), onto which either 5-bromo-4-chloro-3-indolyl-β-d-glucuronide sodium salt (XG), chlorophenol red β-galactopyranoside (CPRG) or both and FeCl₃ were entrapped using sol–gel-derived silica inks in different zones via an ink-jet printing technique. The sample was lysed and assayed via lateral flow through the FeCl₃ zone to the substrate area to initiate …