Role of 2-hydroxyethyl methacrylate in the interaction of dental monomers with collagen studied by saturation transfer difference NMR.
OBJECTIVE
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.


CONCLUSIONS
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.
Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, Japan. Electronic address: hiraope@tmd.ac.jp.
Noriko
N
Hiraishi
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Japan.
Naoya
N
Tochio
NMR Pipeline Methodology Research Team, RIKEN Systems and Structural Biology Center, Japan.
Takanori
T
Kigawa
Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, Japan.
Masayuki
M
Otsuki
Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, Japan.
Junji
J
Tagami
D000818:Animals; D002417:Cattle; D003094:Collagen / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D014233:Tricarboxylic Acids / Q000737:chemistry*
D008689:Methacrylates; D012997:Solvents; D014233:Tricarboxylic Acids; C059821:atelocollagen; C098756:4-methacryloxyethyltrimellitic acid; C005044:hydroxyethyl methacrylate; C069749:methacryloyloxydecyl dihydrogen phosphate; D003094:Collagen; D004121:Dimethyl Sulfoxide
Collagen; Dentine bonding agent; Hydroxyethylmethacrylate; Ligand–protein interactions; NMR spectroscopy