Quaternized Zn(II) phthalocyanines for photodynamic strategy against resistant periodontal bacteria
AbstractPhotodynamic inactivation (PDI) has been featured as an effective strategy in the treatment of acute drug-resistant infections. The efficiency of PDI was evaluated against three periodontal pathogenic bacteria that were tested as drug-resistant strains. In vitro studies were performed with four water-soluble cationic Zn(II) phthalocyanines (ZnPc1–4) and irradiation of a specific light source (light-emitting diode, 665 nm) with three doses (15, 36 and 60 J/cm2). The well detectable fluorescence of ZnPcs allowed the cellular imaging, which suggested relatively high uptakes of ZnPcs into bacterial species. Complete photoinactivation was achieved with all studied ZnPc1–4forEnterococcus faecalis(E. faecalis) at a light dose of 15 J/cm2. The photodynamic response was high forPrevotella intermedia(P. intermedia) after the application of 6 μM of ZnPc1and a light dose of 36 J/cm2and for 6 μM of ZnPc2at 60 J/cm2.P. intermediawas inactivated with ZnPc3(4 log) and ZnPc4(2 log) with irradiation at an optimal dose of 60 J/cm2. Similar photoinactivation results (2 log) were achieved forAggregatibacter actinomycetemcomitans(A. actinomycetemcomitans) treated with 6 μM ZnPc1and ZnPc2at a light dose of 60 J/cm2. The study suggested that PDI with quaternized Zn(II) phthalocyanines and specific light irradiation appears to be a very useful antimicrobial strategy for effective inactivation of drug-resistant periodontal pathogens.