Date on Master's Thesis/Doctoral Dissertation

12-2015

Document Type

Master's Thesis

Degree Name

M.S.

Department

Oral Biology

Degree Program

Oral Biology, MS

Committee Chair

Demuth, Donald

Committee Co-Chair (if applicable)

Steinbach-Rankins, Jill

Committee Member

Lamont, Richard

Author's Keywords

dental plaque biofilms; dual species biofilms; porphyromonas gingivalis; nanoparticles; BAR peptide

Abstract

Periodontal disease is an oral inflammatory disorder that afflicts roughly 46% of the adults in the U.S. Currently, treatment of periodontal disease involves the removal of plaque from the gingival pocket (with possible antibiotic treatment) and if necessary, gingival surgery. To our knowledge, no therapeutic approach exists that promotes host-biofilm homeostasis by limiting pathogen recolonization of the oral cavity after prophylaxis or treatment. The interaction of the pathogen Porphyromonas gingivalis with commensal streptococci is critical for initiation of periodontitis and represents a target for limiting P. gingivalis colonization of the oral cavity. Previous studies showed that a synthetic peptide (BAR) derived from antigen I/II protein of Streptococcus gordonii potently inhibited P. gingivalis adherence to streptococci. However, BAR was less effective in preventing P. gingivalis adherence in a more complex three species biofilm model, suggesting that the potency of BAR against complex biofilms may be reduced. This study focuses on designing surface-modified poly(lactic-co-glycolic acid; PLGA)nanoparticles (NPs) that are functionalized with BAR to increase its inhibitory potency by multivalent binding with P. gingivalis. Biotinylated BAR was conjugated to the surface of avidin-palmitylated PLGA NPs. We generated NPs with particle size of 100±28nm and Zeta Potential of -12mV. The surface modification of avidin-NPs with BAR was examined using two approaches. Comparing the binding of biotin-PEG FITC with avidin-NPs and avidin-NPs that were reacted with biotinylated BAR showed that BAR binding efficiency was approximately 98%. In addition, reacting avidin-NPs with fluorescently labeled BAR showed that a concentration of 37.1 nmol BAR/mg NPs resulted in maximal BAR binding. We also showed that BAR-NPs bound to P. gingivalis in a dose-dependent manner and significantly (PP. gingivalis/S. gordonii biofilm formation (50% inhibitory concentration = 0.3 μM) making it 4.5 times more potent than soluble BAR. Together this platform represents a potential therapeutic approach to effectively target an initial interaction involved in P. gingivalis colonization of the oral cavity.