TY - JOUR
T1 - Tetrahedral (T) Closed-Shell Cluster of 29 Silver Atoms & 12 Lipoate Ligands, [Ag29(R-α-LA)12](3-)
T2 - Antibacterial and Antifungal Activity
AU - Lopez, Priscilla
AU - Lara, Humberto H.
AU - Mullins, Sean M.
AU - Black, David M.
AU - Ramsower, Heidi M.
AU - Alvarez, Marcos M.
AU - Williams, Tayler L.
AU - Lopez-Lozano, Xochitl
AU - Weissker, Hans Christian
AU - García, A. Patricio
AU - Garzón, Ignacio L.
AU - Demeler, Borries
AU - Lopez-Ribot, José Luis
AU - Yacamán, Miguel José
AU - Whetten, Robert L.
N1 - Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/4/27
Y1 - 2018/4/27
N2 - Here we report on the identification and applications of an aqueous 29-atom silver cluster stabilized with 12 lipoate ligands, i.e. Ag29(R-α-LA)12 or (29,12), wherein R-α-LA = R-α-lipoic acid, a natural dithiolate. Its uniformity is checked by HPLC-ESI-MS and analytical ultracentrifugation, which confirms its small dimension (∼3 nm hydrodynamic diameter). For the first time, this cluster has been detected intact via electrospray ionization mass spectrometry, allowing one to confirm its composition, its [3-] charge-state, and the 8-electron shell configuration of its metallic silver core. Its electronic structure and bonding, including T-symmetry and profound chirality in the outer shell, have been analyzed by DFT quantum-chemical calculations, starting from the known structure of a nonaqueous homologue. The cluster is effective against Methicillin-Resistant Staphylococcus aureus bacteria (MRSA) at a minimum inhibitory concentration (MIC) of 0.6 mg-Ag/mL. A preformed Candida albicans fungal biofilm, impermeable to other antifungal agents, was also inhibited by aqueous solutions of this cluster, in a dose-response manner, with a half-maximal inhibitory concentration (IC50) of 0.94 mg-Ag/mL. Scanning electron micrographs showed the post-treatment ultrastructural changes on both MRSA and C. albicans that are characteristic of those displayed after treatment by larger silver nanoparticles.
AB - Here we report on the identification and applications of an aqueous 29-atom silver cluster stabilized with 12 lipoate ligands, i.e. Ag29(R-α-LA)12 or (29,12), wherein R-α-LA = R-α-lipoic acid, a natural dithiolate. Its uniformity is checked by HPLC-ESI-MS and analytical ultracentrifugation, which confirms its small dimension (∼3 nm hydrodynamic diameter). For the first time, this cluster has been detected intact via electrospray ionization mass spectrometry, allowing one to confirm its composition, its [3-] charge-state, and the 8-electron shell configuration of its metallic silver core. Its electronic structure and bonding, including T-symmetry and profound chirality in the outer shell, have been analyzed by DFT quantum-chemical calculations, starting from the known structure of a nonaqueous homologue. The cluster is effective against Methicillin-Resistant Staphylococcus aureus bacteria (MRSA) at a minimum inhibitory concentration (MIC) of 0.6 mg-Ag/mL. A preformed Candida albicans fungal biofilm, impermeable to other antifungal agents, was also inhibited by aqueous solutions of this cluster, in a dose-response manner, with a half-maximal inhibitory concentration (IC50) of 0.94 mg-Ag/mL. Scanning electron micrographs showed the post-treatment ultrastructural changes on both MRSA and C. albicans that are characteristic of those displayed after treatment by larger silver nanoparticles.
KW - Ag
KW - analytical ultracentrifugation
KW - antibiotic
KW - electrospray ionization mass spectrometry
KW - lipoic acid
KW - silver clusters
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U2 - 10.1021/acsanm.8b00069
DO - 10.1021/acsanm.8b00069
M3 - Article
AN - SCOPUS:85052736017
SN - 2574-0970
VL - 1
SP - 1595
EP - 1602
JO - ACS Applied Nano Materials
JF - ACS Applied Nano Materials
IS - 4
ER -