Dextranase enhances nanoparticle penetration of S. mutans biofilms

Cariogenic biofilms possess a rich extracellular polysaccharide (EPS) matrix, which can reduce the penetration of anticaries agents such as nanoparticle-based technologies. The aim of this study was to assess the potential of dextranase, an EPS-degrading enzyme, to enhance nanoparticle penetration into Streptococcus mutans in vitro biofilms.

Commercially available fluorescent nanoparticles (nanospheres, average diameter around 200 nm) were used as a proxy for nanoparticle treatments. Biofilms of fluorescent S. mutans 3209/pVMCherry were developed over 48 h in 24-well glass bottom microplates, simulating daily feast (tryptic soy broth (TSB) supplemented with 1% sucrose) and famine periods (TSB supplemented with 0.1 mM glucose). Nanoparticles were co-administered to biofilms with either dextranase (10 U/mL) or pH 6.5 phosphate buffer (placebo). Time-lapse confocal laser scanning microscopy was used to capture six image stacks over approximately 60 minutes of nanoparticle movement through the biofilm. In-house-developed quantitative image analysis methods assessed nanoparticle penetration.

Nanoparticle signal intensity and overlapping signal with cells increased in the presence of dextranase, being significantly higher in the last two CLSM scans compared with the initial one (p < 0.05). Biofilm architecture changed under dextranase, increasing the interaction of nanoparticles with biofilm components.

Dextranase showed potential to enhance nanoparticle-based anticaries therapies.

Dextranase increases the penetration of nanoparticles in cariogenic, extracellular polysaccharide-rich dental biofilms.