A glyco-engineered nanoplatform for fluorescence detection and adsorptive elimination of <i>E. coli</i> from water

Rapid and sensitive detection and removal of <i>Escherichia coli</i> (<i>E. coli</i>) in environmental and clinical settings are crucial to prevent infections and to ensure water safety. In this study, we introduce a multifunctional mannosylated graphene oxide (MAN-GO) composite that enables both fluorescence detection and adsorption of <i>E. coli</i>, leveraging the specific interactions between mannose and <i>E. coli</i> fimbriae. The MAN-GO composite demonstrated a limit of detection (LOD) as low as 1.382 × 10⁴ CFU mL^-1 in fluorimetric assays, showcasing high sensitivity and selectivity, even in the presence of interfering species. Adsorption studies reveal that MAN-GO exhibits a maximum adsorption capacity of 448.219 CFU g^-1, with a rapid equilibrium time of 120 minutes, following a pseudo-second-order kinetic model and fitting well with the Langmuir adsorption isotherm (in this work, CFU g^-1 is defined based on the wet mass of the sample for consistency). The maximum adsorption efficiency of the system was identified to be 88.21%, reflecting a highly effective interaction between the adsorbent and the target analyte. The results underscore the potential of the developed material for efficient adsorption applications and indicate its viability for further optimization in practical scenarios. The highly effective adsorption process, driven by the affinity of mannose-functionalized graphene oxide, facilitates a "green" capture and removal of <i>E. coli</i> from aqueous solutions without the need for additional chemical agents. Together, the fluorescent sensing capability and adsorption performance of MAN-GO highlight its potential as a dual-functional material for both the monitoring and mitigation of microbial contamination in aqueous systems, offering a sustainable approach to microbial detection and remediation.