Fig 1.
UV-visible spectra of Carissa carandas leaf mediated synthesized AgNPs (before optimization procedure at pH7 with 1mL of C. carandas leaf extract, 1mM of AgNO3 and a 30 mins reaction), AgNO3, C. carandas leaf extract.
Fig 2.
UV—Vis spectra of AgNPs suspension obtained with Carissa carandas leaf extract at (A) different pH (B) different substrate concentration (C) different silver ion concentration (D) different time intervals.
Fig 3.
Characterization of AgNPs synthesized using Carissa carandas leaf extract using (A)EDX (B) XRD.
Fig 4.
Characterization of AgNPs synthesized using Carissa carandas leaf extract using (A)TEM (B) Histogram (C) SAED (D) FTIR.
Fig 5.
Antibacterial activity of different concentrations of C. carandas mediated synthesized AgNPs against the test pathogens.
Zone of Inhibition in different concentrations (A-25μg/mL, B-50 μg/mL, C-75 μg/mL, D-100 μg/mL, E-125 μg/mL) of AgNPs against Escherichia coli AMB4, Staphylococcus aureus AMB6, Pseudomonas aeruginosa AMB5 are shown.
Fig 6.
Antibacterial comparison of C. carandas mediated synthesized AgNPs, commercial antibiotics (ciprofloxacin), C. carandas leaf extract, AgNO3 against test pathogens.
Zone of inhibition observed in the well of AgNPs, solvent control (DMSO), AgNO3 and commercial antibiotic (ciprofloxacin) against Escherichia coli AMB4, Staphylococcus aureus AMB6, Pseudomonas aeruginosa AMB5 are shown.
Table 1.
Antibacterial activity against uropathogens.
Table 2.
Comparative analysis against uropathogens (ZOI).
Fig 7.
Minimum inhibitory concentration for different concentrations (20, 40, 60, 80, 100, 120, 140, and 160μg/ml) of AgNPs against Escherichia coli AMB4, Pseudomonas aeruginosa AMB5, Staphylococcus aureus AMB6.
Table 3.
Zone of inhibition of different antibiotics against uropathogens with presence and absence of AgNPs.
Fig 8.
Urinary catheter coated with AgNPs and uncoated catheter (A) C. carandas leaf mediated synthesized AgNPs coated urinary catheter of size 1× 1 cm (B) uncoated urinary catheter of size 1×1 cm.
Fig 9.
Biofilm inhibition percentage of AgNPs coated catheter.
AgNPs coated catheter with different concentration of 20,40,80,120,160 μg/mL shows biofilm inhibition towards Escherichia coli AMB4, Pseudomonas aeruginosa AMB5, Staphylococcus aureus AMB6.
Fig 10.
SEM analysis of urinary catheter (A) SEM micrograph of uncoated urinary catheter (control) (B) SEM micrograph of urinary catheter coated with 30 μg/mL of AgNPs, arrow indicate the coating of AgNPs (C) SEM micrograph of biofilm mat formed by Escherichia coli AMB4 over uncoated urinary catheter, arrow indicates the mat formation (D) SEM micrograph showing the disruption of biofilm formed by Escherichia coli AMB4 over AgNPs coated urinary catheter, arrow indicates the disruption of biofilm.
Fig 11.
Proposed antibacterial mechanism of plant mediated AgNPs showing various inhibiting properties of AgNPs.
1) AgNPs interact with ribosome and inhibit the translation; 2) AgNPs have electrostatic interaction with the cell wall which ultimately causes the leakage of internal substances; 3) AgNPs interact with sulfhydryl group of enzymes and proteins, hence protein denaturation takes place; 4) AgNPs inactivates the respiratory chain and excess ROS generation, results in the apoptosis; 5) AgNPs anchor the cell wall of the bacteria and causes damages to the cell membrane and the cellular content get leaked.
Fig 12.
Proposed antibiofilm mechanism of plant mediated AgNPs.
1) AgNPs has electrostatic interaction with the cells and disturb the biofilm formation; 2) AgNPs target the eDNA to eliminate bacterial biofilm; 3) AgNPs degrade the EPS formation and breaks the biofilm mat; 4) AgNPs inhibits the signal produced by the bacteria, thereby inhibiting the biofilm formation; 5) interact with the small regulatory RNA and extracellular protein to inhibit the biofilm.