Revealing the significance of glycan binding property of butea monosperma seed lectin for enhancing the antibiofilm activity of silver nanoparticles against uropathogenic Escherichia coli.

The incompetence of conventional antibiotics against the bacteria residing in biofilm demands for newer therapeutic intervention. In this study, we demonstrated that the interaction between silver nanoparticles (AgNPs) and butea monosperma seed lectin (BMSL) form an efficient surface functionalized AgNPs with excellent antibiofilm competency against uropathogenic Escherichia coli (UPEC). The minimum biofilm inhibitory concentration (MBIC) of AgNPs and BMSL-AgNPs conjugate (BAgNPs) against UPEC was 75 M and 9.37 M, respectively. The eight folds reduction in MBIC of AgNPs was attributed to lectin func-tionalization. Chemical modification of Serine amino acids affects the hemeagglutination activity of BMSL, but not the interaction with AgNPs. At the same time, AgNPs surface functionalized with modified BMSL display poor antibiofilm activity. Molecular docking studies revealed BMSL binds to galactose with free energy of -5.72 kcal/mol, whereas Serine residue modified BMSL showed lowest free energy values, suggesting incompetence to bind galactose. These results showcases that the sugar binding site of BMSL aid the adhesion of AgNPs to the biofilm matrix and disturb the biofilm formation, which was confirmed by light micros-copy using crystal violet staining. BAgNPs also have the capability to eradicate pre-formed biofilm at 37.5 µM. As a proof of con-cept, UPEC biofilm prevention and eradication was demonstrated on urinary catheter. Scanning electron microscopy study showed that BAgNPs prevents the bacterial colonization to curtail biofilm growth. Besides antibiofilm activity, BAgNPs exert antibacterial activity at 18.75 µM, which is four fold lower than the MIC of AgNPs. Mechanistic study revealed that BAgNPs affects the bacte-rial outer membrane integrity and generates an imbalance in antioxidant defense to induce cell death. The results highlights that the lectin functionalization can be extended to other nanoparticles and different antibiotics to enhance their efficacy against drug resistance bacteria.