Polymeric nanoparticles enhance the phototoxicity of monobrominated azure b against gram-positive and gram-negative bacteria.

VARA, JIMENA; GUALDESI, MARÍA S; AIASSA, VIRGINIA; ALVAREZ IGARZABAL, C.I.; ORTIZ, CRISTINA S.

Mar del Plata

Congreso; Reunión Anual de Sociedades de Biociencia 2019.; 2019

SAIC, SAFE, SAB y SAP.

Phenothiazine are commonly used Photosensitizer (PS) due to their low toxicity, high binding affinity for both Gram-positive and Gram-negative bacteria. In order to optimize the properties of these dyes, monobrominated derivative of Azure B (AzBBr) was synthesized. Although halogenation increased the singlet oxygen quantum yield of this PS, also increased the lipophilicity, favored aggregation and affected its phototoxic efficiency. The vehiculization of this PS in different Polyacrylamide Nanoparticles (PAA-NP) was employed to overcome these disadvantages. In this work we evaluated the photodynamic efficacy of AzBBr, free and loaded in two PAA-NP (NIPA and BIS, according to its components), against Gram-positive and Gram-negative bacteria.The inactivation of Staphylococcus aureus sensitive and resistant to methicillin (MSSA and MRSA), Pseudomonas aeruginosa and Escherichia coli was tested in bacterial suspensions. Different concentrations of the PS (7.5-250 μM) and light doses (7.6-15.1 J/cm2) were applied in the treatment. The results showed that AzBBr, free and loaded in PAA-NP, were not toxic and caused significant photodynamic inactivation of all bacteria studied. S. aureus was the most sensitive bacterium to photodynamic treatment, evidencing a similar behavior in the inactivation of MSSA and MRSA. After 15 min of irradiation, the PAA-NP produced a reduction greater than 3 Log CFU/mL. Regarding Gram-negative bacteria, AzBBr loaded in NIPA-NP eradicated P. aeruginosa and caused a drop greater than 3 Log CFU/mL of E. coli. On the other hand, the BIS-NP enhanced the phototoxic activity of the PS, reaching a drop of 3 Log CFU/mL of P. aeruginosa and 2 Log CFU/mL of E. coli.In conclusion, the employ of PAA-NP in the vehiculization of AzBBr increased the photodynamic efficacy of PS against Gram-positive and Gram-negative bacteria. Particularly NIPA-NP is a promising alternative for the use of AzBBr in the treatment of infections caused by these microorganisms.