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Sci Rep. 2015 Oct 23;5:15564. doi: 10.1038/srep15564.

Subdiffraction localization of a nanostructured photosensitizer in bacterial cells.

Author information

1
Dipartimento di Fisica e Scienze della Terra, Università di Parma, Viale delle Scienze 7A, 43124 Parma, Italy.
2
Fondazione Istituto Italiano di Tecnologia, Via Morego, 30, 16163 Genova, Italy.
3
Institut Quimic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain.
4
LENS (European Laboratory for Nonlinear Spectroscopy) Via N. Carrara 1, Sesto Fiorentino, Florence 50019, Italy.
5
INO (Istituto Nazionale di Ottica), Largo Fermi 6, Florence 50125, Italy.
6
Dipartimento di Chimica, Università di Perugia, via Elce di Sotto 8, Perugia, 06123 Italy.
7
Dipartimento di Bioscienze, Università di Parma, Viale delle Scienze 11A, 43124 Parma, Italy.
8
NEST, Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, Piazza San Silvestro 12, 56127 Pisa, Italy.

Abstract

Antibacterial treatments based on photosensitized production of reactive oxygen species is a promising approach to address local microbial infections. Given the small size of bacterial cells, identification of the sites of binding of the photosensitizing molecules is a difficult issue to address with conventional microscopy. We show that the excited state properties of the naturally occurring photosensitizer hypericin can be exploited to perform STED microscopy on bacteria incubated with the complex between hypericin and apomyoglobin, a self-assembled nanostructure that confers very good bioavailability to the photosensitizer. Hypericin fluorescence is mostly localized at the bacterial wall, and accumulates at the polar regions of the cell and at sites of cell wall growth. While these features are shared by Gram-negative and Gram-positive bacteria, only the latter are effectively photoinactivated by light exposure.

PMID:
26494535
PMCID:
PMC4616064
DOI:
10.1038/srep15564
[Indexed for MEDLINE]
Free PMC Article

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