Targeted Delivery of a Photosensitizer to Aggregatibacter actinomycetemcomitans Biofilm

Abstract

The ability to selectively target specific biofilm species with antimicrobials would enable control over biofilm consortium composition, with medical applications in treatment of infections on mucosal surfaces that are colonized by a mixture of beneficial and pathogenic microorganisms. We functionalized a genetically engineered multimeric protein with both a targeting moiety (biotin) and either a fluorophore or a photosensitizer (SnCe6). Biofilm microcolonies of Aggregatibacter actinomycetemcomitans, a periodontal pathogen, were targeted with the multifunctional dodecamer. Streptavidin was used to couple biotinylated dodecamer to a biotinylated anti-A. actinomycetemcomitans antibody. This modular targeting approach enabled us to increase the loading of photosensitizer onto the cells by a cycle of amplification. Scanning laser confocal microscopy was used to characterize transport of fluorescently tagged dodecamer into the microcolonies and targeting of the cells with biotin-labeled, fluorescently tagged dodecamer. Light-induced activity of the targeted photosensitizer reduced the viability of A. actinomycetemcomitans biofilm, as indicated by membrane permeability to propidium iodide. The functionalized multimeric protein promises to be a useful tool for controlling periodontal biofilm consortia and offers a modular design whereby moieties that target different species can be readily combined with the functionalized protein construct.

Photodynamic inactivation of clinical isolates ofCandidausing Photodithazine®

“…This fact could be responsible for biofilm resistance to PDI when compared with their planktonic counterparts. In an attempt to overcome this problem, investigations into the use of chlorin e6 for antibacterial PDI have frequently used chlorin conjugates to increase phototoxicity towards biofilms (Soukos et al 2003;Garcez et al 2007;Suci et al 2010). The difficulty of PS in penetration into the inner layers of biofilms may also be explained by the possibility of aggregate formations at high concentrations of the PS.…”

Aggregatibacter actinomycetemcomitansbiofilm killing by a targeted ciprofloxacin prodrug

“…Media for culturing Aa consisted of modified tryptic soy broth (MTSB; Suci et al 2010). Frozen stocks were maintained at −80°C in 20% glycerol, 80% MTSB.…”

Extracellular Heme Uptake and the Challenges of Bacterial Cell Membranes

“…Although it has been shown that E. coli overexpressing the Hb receptor of P. gingivalis binds both Cu- and Zn-PPIX with similar affinity as Fe-PPIX, their remains no direct evidence for active transport of noniron porphyrins into the periplasm (Olczak, Dixon, & Genco, 2001). Despite promising early studies on the OM heme receptors as Trojan horses in delivering noniron metalloporphyrin antibacterials, most of the current focus has been directed at utilizing the photodynamic properties of light-activated Sn-chlorins as antibacterials (Embleton et al, 2002, 2005; Suci, Kang, Gmur, Douglas, & Young, 2010). …”