Labeling and Selective Inactivation of Gram-Positive Bacteria Employing Bimodal Photoprobes with Dual Readouts

• Published in: Chemistry : a European journal Vol. 22; no. 15; pp. 5243 - 5252
• Main Authors: Galstyan, Anzhela, Block, Desiree, Niemann, Silke, Grüner, Malte C., Abbruzzetti, Stefania, Oneto, Michele, Daniliuc, Constantin G., Hermann, Sven, Viappiani, Cristiano, Schäfers, Michael, Löffler, Bettina, Strassert, Cristian A., Faust, Andreas
• Format: Journal Article
• Language: English
• Published: WEINHEIM Blackwell Publishing Ltd 04.04.2016; Wiley; Wiley Subscription Services, Inc
• Subjects: Antibiotic resistance; Antibiotics; Bacteria; Carbohydrates; Carbohydrates - chemistry; Chemistry; Chemistry, Multidisciplinary; Constitution; Deactivation; Drug resistance; Fluorescence; Fluorescence microscopy; fluorescence spectroscopy; Fluorescent indicators; fluorescent probes; Gram-positive bacteria; Gram-Positive Bacteria - chemistry; Gram-Positive Bacteria - drug effects; I.R. radiation; Inactivation; Indoles - chemistry; Labeling; Labels; Luminescence; Mannose; Marking; Methicillin; Methicillin-Resistant Staphylococcus aureus - chemistry; Methicillin-Resistant Staphylococcus aureus - drug effects; Microorganisms; Microscopy; Near infrared radiation; Pathogens; photophysics; Photosensitization; Photosensitizing Agents - chemistry; Photosensitizing Agents - pharmacology; Physical Sciences; Probes; Science & Technology; Silanes - chemistry; Silicon; singlet oxygen; Staphylococcus aureus; Staphylococcus aureus - chemistry; Staphylococcus aureus - drug effects; SYSTEM; OUTER-MEMBRANE; PHOTODYNAMIC THERAPY; ESCHERICHIA-COLI; fluorescence spectroscopy; PHOTOPHYSICAL PROPERTIES; fluorescent probes; J-AGGREGATE; SUBSTRATE-SPECIFICITY; TRANSPORT; silicon; singlet oxygen; STRUCTURAL BASIS; PHTHALOCYANINE; photophysics
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201504935

Carbohydrate‐conjugated silicon(IV) phthalocyanines with bimodal photoactivity were developed as probes with both fluorescent labeling and photosensitizing capabilities, and the concomitant fluorescent labeling and photoinduced inactivation of Gram‐positive and Gram‐negative models was explored. The maltohexaose‐conjugated photoprobe provides a dual readout to distinguish between both groups of pathogens, as only the Gram‐positive species was inactivated, even though both appeared labeled with near‐infrared luminescence. Antibiotic resistance did not hinder the phototoxic effect, as even the methicillin‐resistant pathogen Staphylococcus aureus (MRSA) was completely photoinactivated. Time‐resolved confocal fluorescence microscopy analysis suggests that the photoprobe sticks onto the outer rim of the microorganisms, explaining the resistance of Gram‐negative species on the basis of their membrane constitution. The mannose‐conjugated photoprobe yields a different readout because it is able to label and to inactivate only the Gram‐positive strain. Bimodal probes: A versatile toolbox is presented for the construction of two phototriggered bimodal probes with distinctive readouts for the discrimination of E. coli and S. aureus. Because of their intrinsic fluorescence, the probes are able to label pathogens with or without selectivity for the Gram‐positive bacteria on the basis of the attached carbohydrate (see figure).