Selection of streptococcal glucan-binding protein C specific DNA aptamers to inhibit biofilm formation

Streptococcus mutans is a commensal oral bacterium, yet its capacity for extensive biofilm formation is a major contributor to dental caries. This study presents a novel biofilm inhibition strategy by targeting GbpC, a cornerstone protein in S. mutans biofilm architecture, with specific DNA aptamers. Using SELEX (Systematic Evolution of Ligands by EXponential enrichment), we selectively targeted the extracellular domain of GbpC while incorporating structurally similar antigen I/II protein and a GbpC-deficient S. mutans strain as counter-targets to ensure high specificity. Aptamer selection was further refined through a panning method that combined primer-blocked asymmetric PCR with AlphaScreen technology. Detailed binding analyses via biolayer interferometry and microscale thermophoresis confirmed the interaction between top aptamer candidates and GbpC. Functional assays demonstrated that two lead aptamers evidently inhibited biofilm formation in wild-type S. mutans without affecting the GbpC-deficient strain, highlighting the aptamers' specificity. These results confirm that the selected aptamers retain specificity even in the complex bacterial culture matrix, validating the efficacy of our selection approach. Notably, these aptamers represent the first instance of using DNA aptamers to inhibit S. mutans biofilm formation by disrupting glucan binding. These aptamers hold promise as lead molecules for the development of biofilm-targeting therapies in dental care.