Preparation and optimization of grapefruit seed extract-loaded nanoparticles for improving antimicrobial activity against oral bacteria

??????????????? ????????? ????????? ?????? ?????????????????? ????????? ???????????? ?????? ???????????? ????????? ??? ?????????, Streptococcus mutans??? Streptococcus sobrinus??? ????????? ?????? ????????? ???????????????. ????????? ???????????? ????????? ???????????? ?????? ?????? ???????????? ?????????????????? ?????? ?????? ???????????? ?????? ?????????????????????, ?????? ????????? ?????? ?????? ??????, ?????? ??????, ?????? ?????? ???????????? ???????????? ?????? ?????? ?????? ?????? ????????? ?????? ????????? ???????????? ??????. ?????? ???????????????????????? ?????? ?????? ?????? ?????? ????????? ????????? ??? ?????????, ?????? ????????? ????????? ?????? ????????? ?????????, ??????????????? ???????????? ?????? ??????????????? ????????? ????????? ??????. ????????? ??? ????????? ???????????? ????????? ????????? ???????????????????????? ????????? ????????????, ?????? ????????? ?????????????????? ?????????. ?????? ???????????? ?????????????????? ?????? ????????? ????????? ????????? ????????? ???????????? ??????????????????????????? ???????????? ????????? ??? ?????????????????? ?????? ????????? ????????? ??????????????? ??????????????? ?????????. ????????? ???????????? ????????? ???????????? ????????? ??????????????? ???????????? ?????? ????????? ????????? ??????, ??? ????????? ??????????????? ????????? ??????????????? ????????????????????? ?????? ????????? ???????????? ????????? ?????? ?????? ?????? ?????????. ????????? ????????? ??????????????? ????????? ??????????????? ????????? ??????????????? ????????? ??????????????? ????????? ??????????????? ????????????, ???????????????????????? ?????? ??? ??????????????? ?????? ????????? ???????????????. ???????????????????????? ?????? ??? ??????????????? ?????? ?????? 300 nm ?????? 600 nm ??? ?????? ?????? ????????? ???????????????. ?????? ?????? ????????? ???????????????????????? ?????? ??? ??????????????? ????????? ?????? ?????? ???????????????????????? ????????? S. mutans??? ?????? ?????? ????????? ????????? ????????? ??????????????????, ?????? time-kill ???????????? ?????? ????????? ?????? ?????? 300 nm??? ??????????????? ?????? ????????? ?????? ???????????? ???????????????. ???????????? ?????? ?????? ????????? ????????? ????????? ?????? ????????? ???????????????????????? ????????? ???????????? ????????????, ??????????????? ????????? ???????????????. ????????? ???????????????????????? ???????????? ?????? ????????? ??????????????? ????????? ?????? ???????????????????????? ?????? ??? ??????????????? ??????????????? ?????????. ?????? ???????????? ????????? ???????????? ??????????????????????????? ????????? ??????????????????, ?????? ???????????? ????????? 0.45 mg/mL??? ???????????????????????? 0.30 mg/mL??? ???????????????. ???????????? ???????????????????????? ?????? ??? ??????????????? ????????? ?????? ?????? ???????????????????????? ????????? ?????? ?????? ???????????? 2??? ?????? ????????????, S. mutans??? S. sobrinus??? ?????? ?????? ?????? ?????? ?????? ???????????? ?????? ????????? ????????? ???????????????. ???????????????????????? ?????? ??? ??????????????? ?????? ????????? ??????????????? ???????????????????????? ???????????? ???????????? ????????? ???????????????. ???????????????????????? ?????? ??? ??????????????? ???????????? ???????????? ????????? ????????? ?????? ?????? ??? ????????? ????????? ???????????????. ????????? ???????????? ???????????????????????? ??? ????????? ??????????????? ??? ????????? ?????? ????????? ????????? ??????????????? ??????????????????, ???????????????????????? ?????? ?????? ?????? ????????? ?????????????????? ??????????????? ?????? ?????? ?????? ???????????????????????? ?????? ????????? ????????? ????????? ???????????? ??? ?????? ???????????? ????????????????????? ?????? ?????? ??????????????? ?????? ???????????? ???????????????.The aim of this study was to develop antimicrobial nanoparticles (NPs) using chitosan (CS) and sodium dodecyl sulfate (SDS) as wall materials and to prove the influence of particle size on the antimicrobial activity against oral bacteria. Water-insoluble chitosan (WIC), water-soluble chitosan (WSC), and SDS were selected as the wall materials to provide antimicrobial activity for NPs. After WIC NPs and WSC NPs were prepared in different sizes ranging from 300 to 600 nm, their characteristics were compared. With respect to minimum inhibitory concentrations (MICs), there were no differences in the MICs of any CS/SDS NPs, indicating that WIC NPs and WSC NPs can be used as antimicrobial carriers. In terms of redispersibility, the WSC NPs were more stable than the WIC NPs after drying, therefore WSC NPs were selected as the antimicrobial carriers for grapefruit seed extract (GSE) encapsulation. The physically stable GSE-loaded NPs (GNPs) were prepared in different sizes (300-600 nm) to analyze their antimicrobial activity. The MICs of all GNPs against Streptococcus mutans were three times lower than those of free GSE were. In the time-kill assays, GNPs with 300 nm diameters showed the significantly highest antimicrobial activity among all samples (p<0.05). Thus, this study demonstrates the great potential of WSC/SDS NPs as antimicrobial carriers against oral bacteria. Response surface methodology (RSM) was used to optimize the preparation conditions for grapefruit seed extract (GSE)-loaded nanoparticles (NPs) by minimizing particle size while maintaining particle quality. Independent variables included water-soluble chitosan (WSC, X1, mg/mL) and sodium dodecyl sulfate (SDS, X2, mg/mL) concentrations. The optimized values of X1 and X2 were found to be 0.45 and 0.30 mg/mL, respectively. The solubility of optimized GSE NPs was at least two-fold higher relative to non-nanoencapsulated counterparts. The MIC of GSE NPs was about 10-fold lower than that of free GSE, and equal in value to blank NPs. In addition, time-kill assays showed that antimicrobial activity of GSE NPs was significantly higher than blank NPs and free GSE due to nanoencapsulation synergy effects (p