Bioactive Chlorhexidine-Loaded Nanoparticle Restorative Materials: Evaluation of Antimicrobial Activity, Biocompatibility, and Proteolytic Enzyme Inhibition

• Grant number: 25/00526-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: August 28, 2025
• End date: August 27, 2026
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Karina Cogo Müller
• Grantee: Larissa Pavanello Pandolfo
• Supervisor: Ana Paula Piovezan Fugolin
• Host Institution: Faculdade de Ciências Farmacêuticas (FCF). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: Oregon Health & Science University, United States
• Associated to the scholarship: 23/11067-0 - Physicochemical properties, antimicrobial activity and cytotoxicity of multilayer silica nanoparticles with chlorhexidine incorporated into dental composites: in situ study, BP.DR

Abstract

Approximately 50% of dental resin composite restorations fail within 10 years, largely due to collagen degradation at the material-tooth interface. Chlorhexidine (CHX) has demonstrated extensive antimicrobial properties and strong inhibition of matrix metalloproteinases (MMPs), key enzymes involved in collagen degradation. However, the clinical application of CHX remains limited by its low substantivity and short therapeutic duration. To overcome these challenges, this proposal aims to develop a novel approach for the localized, sustained, and stimuli-responsive delivery of CHX. Two responsive carriers will be engineered: one for incorporation into resin composite formulations and another for dental adhesive systems. For the resin composite, multilayered silica nanoparticles loaded with CHX (CHX-SNPs) will be developed and evaluated for their biological properties (phase I). For the dental adhesive, CHX will be encapsulated in MMP-responsive nanoparticles designed to release the compound in environments with active MMP-2/-9. These nanoparticles will be fully characterized and incorporated into the adhesive primer and characterized for their performance (phase II). In Phase I, eight resin composite formulations containing CHX-SNPs will be prepared using a BisGMA/TEGDMA (1:1) organic matrix and colloidal silica with varying concentrations of barium glass as the inorganic component. Their antimicrobial properties will be assessed using a bioluminescent single-species Streptococcus mutans strain (IdhRenGSm) via a luciferase assay, and the biocompatibility evaluated by the colorimetric AlamarBlue® assay in human dental pulp stem cells (hDPSCs). In Phase II, CHX-containing enzyme-responsive nanoparticles will be synthesized through a multi-step procedure and thoroughly characterized using Transmission Electron Microscopy, Dynamic Light Scattering, zeta potential analysis, encapsulation efficiency, loading capacity, in vitro drug release studies, physical stability assessments, and cytotoxicity tests in hDPSCs. These responsive nanoparticles will then be incorporated into a commercial primer (SE Bond, Kuraray). Their effectiveness in inhibiting MMP will be evaluated using a state-of-the-art microfluidic device, while the preservation of bonding performance will be tested through dentin microtensile bond strength experiments. The experimental composite will also be used to restore teeth in these evaluations. In summary, this project aims to enhance the durability and therapeutic efficacy of dental restorations by enabling targeted and sustained CHX release, addressing a critical challenge in restorative dentistry.