Separation and detection of mutans streptococci by using magnetic nanoparticles stabilized with a cell wall binding domain-conjugated polymer

摘要: A number of salivary mutans streptococci (MS: Streptococcus and sobrinus) are used in dental caries risk assessment. In this study, a simple, yet effective assay was developed for MS detection. Magnetic nanoparticles (MNPs) were first grafted with poly(acrylic acid) that bears active carboxyl groups available conjugation the cell wall binding domain (CWBD) automutanolysin which specifically binds to MS. The efficiency CWBD-conjugated MNPs tested pure cultures streptococcal standard strains. After mixing culture, bacteria-bound particles separated from unbound cells using magnet filtered through cellulose acetate membrane (pore-size 0.8 μm). color intensity remaining on represents bound bacteria. showed higher S. sobrinus than non-mutans (S. sanguinis salivarius) capture efficiencies 77 69% 38 15% non-MS. Moreover, method can quantify range 102 107 colony-forming units (CFU) mL−1, covers levels calculated limit detection 16 72 CFU mL−1 sobrinus, respectively. Furthermore, could be efficiently human saliva samples containing highly complex mixtures bacterial species. These results suggest applicable as simple tool determination not only clinical settings but also community fields without expert requirement.