Probiotic Outer Membrane-Encapsulated Antimicrobial Delivery System against Cariogenic Tristreptococcal Species Biofilms and Oral Caries

An in vitro model intended to mimic the cariogenic conditions found in the oral cavity is the tristreptococcal species biofilms. Extracellular polysaccharides are the main pathogenic element in these biofilms. Owing to the obstruction of dental surface extracellular polysaccharides, conventional antibiotics have a limited residence time in cariogenic biofilms, leading to poor inhibition of dental plaque. To overcome this problem, we drew inspiration from cell membrane-coated nanoparticles (CMCNPs) and synthesized LA/TCS@PLGA by encapsulating triclosan (TCS)-loaded poly(lactic-<i>co</i>-glycolic acid) (PLGA) nanoparticles (TCS@PLGA) with a <i>Lactobacillus acidophilus</i> (LA) outer membrane. The aim of this investigation was to examine how LA/TCS@PLGA penetrate <i>Streptococcus sanguinis</i>, <i>Streptococcus gordonii</i>, and <i>Streptococcus mutans</i> (<i>S.s + S.g + S.m</i>) cariogenic biofilms and inhibit the cariogenic extracellular polymeric substances (EPS) in these biofilms. The LA/TCS@PLGA were stable in terms of size, zeta potential, and sustained drug release kinetics. Moreover, the LA/TCS@PLGA inherited the adhesion ability of the <i>L. acidophilus</i> outer membrane, and compared with the uncoated TCS@PLGA, the LA/TCS@PLGA could adhere to and reside in tristreptococcal species biofilms more extensively and penetrate the inner biofilm layer more deeply with time. Additionally, the LA/TCS@PLGA disrupted the structure of the tristreptococcal species biofilms and reduced the levels of the virulence factor EPS, lactic acid, biomass, total protein, and dry weight. Furthermore, in vivo, LA/TCS@PLGA alleviated the degree or even prevented the occurrence of caries. The nanoparticles also exhibited favorable safety in vivo. The results indicate the excellent application potential of LA/TCS@PLGA in the treatment of oral diseases caused by biofilms.