Figure 1.
Schematic representation of tyrosine-mediated synthesis of gold nanoparticles (AuNPsTyr), followed by their sequential surface functionalization with POMs (PTA or PMA) and lysine (Lys).
Figure 2.
UV-visible absorbance spectra (A) and TEM images of AuNPsTyr (a), AuNPsTyr@PTA (b), AuNPsTyr@PTA-Lys (c), AuNPsTyr@PMA (d) and AuNPsTyr@PMA-Lys (e) with scale bars of 50 nm.
The UV-vis absorbance spectra of pristine PTA and PMA molecules are also shown. Particle size distribution histograms (B-F) correspond to TEM images shown in (a-e), respectively.
Figure 3.
FTIR spectra in Panel A: tyrosine (1) and AuNPsTyr (2); in Panel B: PTA (1), AuNPsTyr@PTA (2), AuNPsTyr@PTA-Lys (3) and lysine (4); and in Panel C: PMA (1), AuNPsTyr@PMA (2), AuNPsTyr@PMA-Lys (3) and lysine (4).
Figure 4.
Antibacterial profile of PTA and PMA functionalized materials against E. coli are shown in Panels A and B, respectively.
Curves 1 and 2 correspond to control bacterial cells (1) and AuNPsTyr (2), respectively. Curves 3 and 4 correspond to AuNPsTyr@PTA (3A), AuNPsTyr@PTA-Lys (a), AuNPsTyr@PMA (3B) and AuNPsTyr@PMA-Lys (4B). Doses on the x-axis correspond to either W (Panel A) or Mo (Panel B), except in curves 2, where it corresponds to equivalent amount of Au as that present in respective curves 4.
Figure 5.
SEM micrographs of E. coli bacterial cells before (A) and after treatments with AuNPsTyr (B), AuNPsTyr@PTA (C), AuNPsTyr@PTA-Lys (D), AuNPsTyr@PMA (E) and AuNPsTyr@PMA-Lys (F).
Scale bars correspond to 1 μm and the regions of damage in treated bacterial cells have been shown by arrows.
Figure 6.
Dose-dependent cytotoxicity profile of AuNPsTyr (1), AuNPsTyr@PTA (2) and AuNPsTyr@PTA-Lys (3) against A549 human lung carcinoma cells.
Figure 7.
Schematic representation of the summary outcome of this work showing increase in antimicrobial activity of AuNPs after their sequential functionalization with POMs and lysine.