Noriko Hiraishi1, Naoya Tochio2, Takanori Kigawa3, Masayuki Otsuki4, Junji Tagami4. 1. Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, Japan. Electronic address: hiraope@tmd.ac.jp. 2. Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Japan. 3. NMR Pipeline Methodology Research Team, RIKEN Systems and Structural Biology Center, Japan. 4. Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, Japan.
Abstract
OBJECTIONS: Functional adhesive monomers are formulated with solvents and hydrophilic resin monomers, such as 2-hydroxyethyl methacrylate (HEMA). In theory, exposed collagen fibrils should be covered and protected by the resin matrix. We examined if the atomic- and molecular-level interaction of monomers with collagen would be affected when the monomers are blended with HEMA. METHODS: We performed saturation transfer difference (STD) NMR spectroscopy to investigate the binding interaction of two functional monomers, 4-methacryloyloxyethyl trimellitic acid (4-MET) and 10-methacryloyloxydecyl dihydrogen phosphate (MDP), with atelocollagen as a triple-helical peptide model. The STD NMR measurement was performed by adding 4-MET or MDP to the atelocollagen solution. RESULTS: When the atelocollagen was saturated, the STD signals were detected in the MDP spectrum for the protons in the aliphatic chain when MDP was dissolved in DMSO. However, the STD signals disappeared when MDP was mixed with HEMA. No STD signal was visible for the 4-MET ligand samples in either DMSO or for the HEMA blend sample. DISCUSSION: The interaction of MDP with atelocollagen is hydrophobic; however, the MDP-HEMA blend may form an aggregate in the atelocollagen solution, which would suppress the hydrophobicity of MDP. The formation of the MDP-HEMA aggregate may compromise the MDP-collagen interaction, and leave the collagen fibrils unprotected by MDP and HEMA. Unstable chemical interaction of the monomers with the exposed collagen may deteriorate hybrid layer integrity and strong dentine bonding.
OBJECTIONS: Functional adhesive monomers are formulated with solvents and hydrophilic resin monomers, such as 2-hydroxyethyl methacrylate (HEMA). In theory, exposed collagen fibrils should be covered and protected by the resin matrix. We examined if the atomic- and molecular-level interaction of monomers with collagen would be affected when the monomers are blended with HEMA. METHODS: We performed saturation transfer difference (STD) NMR spectroscopy to investigate the binding interaction of two functional monomers, 4-methacryloyloxyethyl trimellitic acid (4-MET) and 10-methacryloyloxydecyl dihydrogen phosphate (MDP), with atelocollagen as a triple-helical peptide model. The STD NMR measurement was performed by adding 4-MET or MDP to the atelocollagen solution. RESULTS: When the atelocollagen was saturated, the STD signals were detected in the MDP spectrum for the protons in the aliphatic chain when MDP was dissolved in DMSO. However, the STD signals disappeared when MDP was mixed with HEMA. No STD signal was visible for the 4-MET ligand samples in either DMSO or for the HEMA blend sample. DISCUSSION: The interaction of MDP with atelocollagen is hydrophobic; however, the MDP-HEMA blend may form an aggregate in the atelocollagen solution, which would suppress the hydrophobicity of MDP. The formation of the MDP-HEMA aggregate may compromise the MDP-collagen interaction, and leave the collagen fibrils unprotected by MDP and HEMA. Unstable chemical interaction of the monomers with the exposed collagen may deteriorate hybrid layer integrity and strong dentine bonding.
Authors: F Yu; M L Luo; R C Xu; L Huang; H H Yu; M Meng; J Q Jia; Z H Hu; W Z Wu; F R Tay; Y H Xiao; L N Niu; J H Chen Journal: Bioact Mater Date: 2021-03-23