In Vitro Antifungal Efficacy of Blue-Light Photodynamic Therapy with Curcumin and Riboflavin Formulation Activated by 450 nm Diode Laser Against Candida albicans Biofilm on Titanium Implants

Abstract

Background: Candida albicans is increasingly recognized in peri-implantitis due to its capacity to form resilient biofilms on implant surfaces, limiting treatment success. Antimicrobial photodynamic therapy (aPDT) may offer a non-invasive adjunct by leveraging photosensitizer activation to produce reactive oxygen species that disrupt microbial cells. This in vitro study assessed the antifungal efficacy of QroxB2, a dual-photosensitizer containing riboflavin and curcumin, activated by 450 nm blue light against C. albicans biofilms on titanium implants. Methods: C. albicans biofilms were formed on 63 titanium implants and randomly assigned to nine groups (n = 7): untreated control (GC), chlorhexidine (CHX), riboflavin (RIB), curcumin (CUR), QroxB2 (QBX), laser only (L), and three photodynamic therapy groups combining laser irradiation with each photosensitizer (L + RIB, L + CUR, L + QBX). Treatments were followed by colony-forming unit (CFU) enumeration. Results: The L + QBX group showed the strongest antifungal effect, achieving a 94% reduction in fungal load, with median CFU counts decreasing from 49,000 in the untreated control to 2800 CFU/mL. CHX eradicated all viable cells (0 CFU/mL). Among photosensitizer-only groups, QBX produced a moderate reduction (median 21,800 CFU/mL), whereas laser irradiation alone (L) exhibited no meaningful antifungal activity, with median counts comparable to the untreated control (49,000 CFU/mL). Conclusions: QroxB2-mediated aPDT achieved a significant reduction in Candida albicans colony-forming units on implant surfaces. While not as potent as chlorhexidine, this light-activated, biocompatible approach may serve as a complementary tool in managing peri-implant fungal infections. Clinical validation is warranted.

Keywords: antimicrobial photodynamic therapy; blue laser; curcumin; peri-implantitis; riboflavin.

Figure 1

Comparison of total yeast load Colony Forming Units per milliliter (CFU/mL) between the growth control (GC) and treatment groups. Statistical comparisons were performed using the Kruskal–Wallis test followed by Dunn’s post hoc test. Significant differences vs. GC are marked: p < 0.01, p < 0.001; ns—not significant. CHX—Chlorhexidine; RIB—Xlinker Gel (riboflavin 0.1%); CUR—Curcumin-Gel 95+; QBX—QroxB2; L—Laser irradiation only; L + RIB—Xlinker Gel + Laser (riboflavin-mediated antimicrobial photodynamic therapy); L + CUR—Curcumin-Gel 95+ + Laser (curcumin-mediated antimicrobial photodynamic therapy); L + QBX—QroxB2 + Laser (QroxB2-mediated antimicrobial photodynamic therapy). ns = not significant ** = p < 0.01 *** = p < 0.001.

Figure 2

Comparison of total yeast load in Colony Forming Units per milliliter (CFU/mL) between treatment groups and the chlorhexidine group (CHX). Statistical comparisons were performed using the Kruskal–Wallis test followed by Dunn’s post hoc test. Significant differences vs. GC are marked: p < 0.01, p < 0.001. GC—Growth Control; RIB—Xlinker Gel (riboflavin 0.1%); CUR—Curcumin-Gel 95+; QBX—QroxB2; L—Laser irradiation only; L + RIB—Xlinker Gel + Laser (riboflavin-mediated antimicrobial photodynamic therapy); L + CUR—Curcumin-Gel 95+ + Laser (curcumin-mediated antimicrobial photodynamic therapy); L + QBX—QroxB2 + Laser (QroxB2-mediated antimicrobial photodynamic therapy). ns = not significant ** = p < 0.01 *** = p < 0.001.

Figure 3

Comparison of total yeast load in Colony Forming Units per milliliter (CFU/mL) among antimicrobial photodynamic therapy groups. Statistical comparisons were performed using the Kruskal–Wallis test followed by Dunn’s post hoc test; ns—not significant. GC—Growth Control; CHX—Chlorhexidine; RIB—Xlinker Gel (riboflavin 0.1%); CUR—Curcumin-Gel 95+; QBX—QroxB2; L—Laser irradiation only; L + RIB—Xlinker Gel + Laser (riboflavin-mediated antimicrobial photodynamic therapy); L + CUR—Curcumin-Gel 95+ + Laser (curcumin-mediated antimicrobial photodynamic therapy); L + QBX—QroxB2 + Laser (QroxB2-mediated antimicrobial photodynamic therapy). ns = not significant.

Figure 4

Median-based percentage reduction in Colony Forming Units per milliliter for each treatment group compared to the growth control (GC). CHX—Chlorhexidine; RIB—Xlinker Gel (riboflavin 0.1%); CUR—Curcumin-Gel 95+; QBX—QroxB2; L—Laser irradiation only; L + RIB—Xlinker Gel + Laser (riboflavin-mediated antimicrobial photodynamic therapy); L + CUR—Curcumin-Gel 95+ + Laser (curcumin-mediated antimicrobial photodynamic therapy); L + QBX—QroxB2 + Laser (QroxB2-mediated antimicrobial photodynamic therapy).