Preferential disruption of E. coli biofilm via ratiometric detection and targeting of extracellular matrix using graphene-oxide-conjugated red-emitting fluorescent copper nanoclusters

Abstract

The emerging demand for antibiofilm coating nanostructures has led to the design of graphene oxide (GO) hosted copper nanoclusters (CuNCs). In this study, we have developed red fluorescence emitting Cu@GO@CTAB nanostructures. The size of the CuNCs in Cu@GO@CTAB was found to be ∼16.7 ± 2.1 nm. The developed nanoassembly showed dual fluorescence emission maxima at ∼474 and ∼645 nm and revealed more promising antibiofilm potential for E. coli (MBIC₅₀ ∼74.1 ± 5.1 μg mL⁻¹) as compared to S. aureus. Interestingly, nanomaterials (NMs) have shown ratiometric interaction towards E. coli isolated extracellular matrix fibrils wherein an isoemissive point was obtained at ∼569 nm. The limit of detection for extracellular matrix fibrils from E. coli and lipopolysaccharide (LPS) was found to be ∼331.1 ± 12.3 and 9.47 ± 1.12 μg mL⁻¹, respectively. Confocal studies suggested that Cu@GO@CTAB NMs can preferentially penetrate and reduce the overall thickness of E. coli biofilm. Motility assays suggested that the developed nanostructures restricted the motility of E. coli and S. aureus. Mechanistic assays for outer and inner membranes suggested that bacterial membrane disruption induced cell death. A displacement assay using BODIPY TR cadaverine (BC) revealed that the prepared NM showed strong binding to LPS of E. coli O26:B6. These studies may pave the path for developing antibacterial and antibiofilm coating agents.