Innovative cationic fullerenes as broad-spectrum light-activated antimicrobials.
Photodynamic inactivation is a rapidly developing antimicrobial technology that combines a nontoxic photoactivatable dye or photosensitizer in combination with harmless visible light of the correct wavelength to excite the dye to its reactive-triplet state that will then generate reactive oxygen species that are highly toxic to cells. Buckminsterfullerenes are closed-cage molecules entirely composed of sp2-hybridized carbon atoms, and although their main absorption is in the UV, they also absorb visible light and have a long-lived triplet state. When C(60) fullerene is derivatized with cationic functional groups it forms molecules that are more water-soluble and can mediate photodynamic therapy efficiently upon illumination; moreover, cationic fullerenes can selectively bind to microbial cells. In this report we describe the synthesis and characterization of several new cationic fullerenes. Their relative effectiveness as broad-spectrum antimicrobial photosensitizers against gram-positive and gram-negative bacteria, and a fungal yeast was determined by quantitative structure-function relationships.


BACKGROUND
Photodynamic inactivation (PDI) is a rapidly developing antimicrobial technology in which a non-toxic photoactivatable dye or photosensitizer is excited with harmless visible light to its reactive state, where it will generate highly toxic reactive oxygen species. Buckminsterfullerenes derivatized with cationic functional groups form molecules that are water-soluble and mediate PDI efficiently. These fullerenes can also selectively bind to microbial cells. Several new cationic fullerenes are presented in this paper, and their efficacy against Gram-positive, Gram-negative bacteria, and a fungal yeast is also demonstrated.
Huang
Liyi
L
Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114-2696, USA.
Terakawa
Mitsuhiro
M
Zhiyentayev
Timur
T
Huang
Ying-Ying
YY
Sawayama
Yohei
Y
Jahnke
Ashlee
A
Tegos
George P
GP
Wharton
Tim
T
Hamblin
Michael R
MR
D000890:Anti-Infective Agents / Q000494:pharmacology* / Q000528:radiation effects*; D001419:Bacteria / Q000166:cytology / Q000187:drug effects; D002412:Cations / Q000737:chemistry; D037741:Fullerenes / Q000737:chemistry / Q000494:pharmacology* / Q000528:radiation effects*; D008027:Light; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D021281:Quantitative Structure-Activity Relationship
D000890:Anti-Infective Agents; D002412:Cations; D037741:Fullerenes