Ultrasound-triggered microbubble delivery of voriconazole for enhanced reduction of Candida albicans biofilms in vitro.

AIMS: This study aimed to develop voriconazole-loaded microbubbles (MBs@VRC) combined with ultrasound-targeted microbubble destruction (UTMD) as a novel strategy to disrupt Candida albicans biofilms and enhance antifungal efficacy, addressing the critical challenge of biofilm-associated resistance in fungal periprosthetic joint infections (PJIs).

METHODS

MBs@VRC were produced using a thin-film hydration method, and their physicochemical properties were evaluated, including size, zeta potential, and drug loading efficiency. The penetration of DiI-labelled MBs@VRC into C. albicans biofilms was visualized via confocal laser scanning microscopy (CLSM). The antibiofilm activity of the UTMD + MBs@VRC treatment was comprehensively assessed on polystyrene, glass, and titanium surfaces using crystal violet staining (biomass quantification), live/dead staining (viability and thickness analysis), scanning electron microscopy (SEM, morphological evaluation), and colony-forming unit (CFU) counting. Furthermore, the cytocompatibility of MBs@VRC was evaluated in RAW 264.7 macrophages.

RESULTS

The synthesized MBs@VRC exhibited a uniform spherical morphology with a mean diameter of 500.87 nm (SD 6.94) and an encapsulation efficiency of 35.33% (SD 2.52%). While C. albicans biofilms showed a notable increase in tolerance, with a minimum biofilm eradication concentration (MBEC50) (1,966.08 μg/ml) approximately 66,000-fold higher than the planktonic minimum inhibitory concentration (MIC) (0.03 μg/ml), MBs@VRC successfully penetrated deep into the 3D biofilm architecture. Compared to monotherapies, the UTMD + MBs@VRC markedly reduced biofilm biomass (by approximately 63% on glass and 73% on titanium), reduced biofilm thickness (as quantified on glass, by approximately 68%), and reduced the viability of C. albicans (by approximately 66% on glass; by approximately 84% on titanium). SEM imaging confirmed extensive hyphal rupture and structural collapse in the combination group. No significant cytotoxicity was observed, with cell viability remaining above 90%.

CONCLUSION

MBs@VRC combined with UTMD effectively disrupts C. albicans biofilms, enhances targeted drug delivery and release, and significantly improves antifungal activity without detectable cytotoxicity. This approach represents a promising adjunctive therapy for combating recalcitrant fungal biofilm infections.