Long-lasting antimicrobial effect of multipurpose ZnO nanoparticle-loaded dental resins enhanced by blue light photodynamic therapy
Maria Luísa Leite, Patricia Comeau, Ala Zaghwan, Ya Shen, Adriana Pigozzo Manso
Abstract
This study aimed to assess the potential of experimental dental resins containing ZnO nanoparticles (ZnO-NPs) for antimicrobial photodynamic therapy (aPDT) as a functional tool for the modulation of cariogenic biofilm in long-term. Minimum inhibitory and bactericidal concentrations (MIC/MBC) of ZnO-NPs against Streptococcus mutans were initially determined under different energy densities of blue LED irradiation (0.00, 1.35, 6.75, or 20.25 J/cm 2 ) to optimize aPDT parameters. Experimental dental resins were then formulated with 0 % (control), 5 %, 10 %, and 20 % ZnO-NPs. Resin disks (1 mm x 6 mm) were prepared to evaluate the antimicrobial and photocatalytic potential of the experimental groups associated with 0 (dark), 1, 2, or 4 light cycles of blue-light irradiation (20.25 J/cm 2 , each cycle). The CFU count and Live/Dead assays were performed on a cariogenic biofilm model ( S. mutans ) on fresh and 6-month aged resin disks. Blue light at 20.25 J/cm 2 decreased MIC (from 250 µg/mL to 125 µg/mL) and MBC (from 1000 µg/mL to 500 µg/mL), establishing the optimal aPDT protocol. Experimental resins with 5 %, 10 %, or 20 % ZnO-NPs, when exposed to 4 cycles of blue light, significantly reduced biofilm viability compared to controls, both initially and after aging. The 20 % ZnO-NP resin sustained > 3.log10 CFU reduction after 6 months, even with 2 cycles of light. Live/Dead assays showed > 50 % dead cells with the 20 % ZnO-NP resin after 2 light cycles. ZnO-NP-loaded dental resins associated with blue light aPDT offer promise as a long-lasting antimicrobial alternative, potentially enhancing the control of pathogenic biofilms. • Blue light triggers antimicrobial effect on lower ZnO nanoparticle (ZnO-NP) levels. • Blue light also enhances antimicrobial effects on ZnO-NP-loaded dental resins. • ZnO-NP-loaded resin are suitable functional material for photodynamic therapy (PDT). • Aging impacts biofilm control on ZnO-NP-loaded dental resin in the absence of light. • ZnO-NP-loaded dental resin combined with PDT offers long-term biofilm control.