Nanoparticle-Mediated Photodynamic Therapy for Mixed Biofilms

Abstract

Wounds associated with diabetes are difficult to heal and often stay unhealed, leading to higher morbidity and mortality in the diabetic population. A major barrier to the successful healing of chronic diabetic wounds is the presence of biofilm-mediated infections. In recent years, photodynamic therapy (PDT) has emerged as a promising treatment modality for the management of chronic wounds. The objective of the present study was to evaluate the effectiveness of toluidine blue- (TB-) loaded nanoparticle-mediated PDT in eradicating antibiotic-resistant polymicrobial biofilms ofPseudomonas aeruginosaand methicillin-resistantStaphylococcus aureusin anin vitromodel. Dioctyl sodium sulfosuccinate (aerosol OT, AOT)-alginate nanoparticles with high TB loading (10.8±2.2%) were formulated using a double emulsification cross-linking method. TB nanoparticles induced effective killing of planktonicP.aeruginosa(3.5 log10CFU) andS.aureus(>5 log10CFU) and their combined biofilms (2.8 log10CFU forP.aeruginosaversus 3.4 log10CFU forS.aureus). WhileP.aeruginosabiofilm was more resistant when compared to that ofS.aureus, our results demonstrated effective eradication of complex biofilms of dual bacterial strainsin vitro.

Antimicrobial photodynamic activity of toluidine blue encapsulated in mesoporous silica nanoparticles againstPseudomonas aeruginosaandStaphylococcus aureus

“…The antimicrobial photodynamic inactivation of planktonic cells after light exposure was higher in TB MSN treated samples than in TB treated samples. Similar to previous literature, Gram-positive cells were more susceptible to aPDT treatment than Gram-negative cells because of the difference in their cell envelopes (Tawfik et al 2015;Usacheva et al 2016).…”

“…One milliliter of methanol was then added to the pellet obtained and the mixture incubated for 1 h at room temperature to extract the cell-bound dye. After incubation, the mixture was centrifuged at 9,838 Âg for 10 min and the absorbance of the supernatant was measured at 620 nm to determine the amount of cell bound-dye using the standard curve of TB (Usacheva et al 2016…”

“…Among fungi, Candida albicans actively forms biofilms in clinical settings, leading to diseases (Van Acker et al 2014). Among bacterial pathogens, P. aeruginosa and S. aureus are the major causes of nosocomial infections; they have the ability to survive under different environmental conditions and resist antibiotics by producing strong biofilms (Usacheva et al 2016).…”

“…The photodynamic effect of TB loaded nanoparticles has been investigated against both planktonic and biofilm cells of P. aeruginosa, MRSA, and their mixed culture (Usacheva et al 2016). The major advantages in using MSN as carrier include its highly ordered structure, tunable particle size, large pore volume and particle size, two functional surfaces (ie a cylindrical pore surface and an external particle surface), and excellent biocompatibility.…”

Biogenic Silver Nanoparticles Decorated with Methylene Blue Potentiated the Photodynamic Inactivation of Pseudomonas aeruginosa and Staphylococcus aureus

“…Sustained release profile of MB could be assigned to the electrostatic interaction between MB and AgNPs. The sustained release of MB from MB-AgNPs can facilitate recurring treatment using aPDT after single illumination [28]. The presence of negative charge around the bacterial cell wall allowed the PS to bind to the bacterial cell, and the intrinsic properties of AgNPs potentially increased the internalization of the dye into the bacterial cell.…”