Hiraishi Noriko, Tochio Naoya, Kigawa Takanori, Otsuki Masayuki, Tagami Junji
Cariology and Operative Dentistry, Department of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, Japan.
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Japan.
J Dent. 2014 Apr;42(4):484-9. doi: 10.1016/j.jdent.2013.12.016. Epub 2014 Jan 17.
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.
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.
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.
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.
功能性粘结单体是与溶剂和亲水性树脂单体（如甲基丙烯酸2-羟乙酯，HEMA）一起配制的。理论上，暴露的胶原纤维应由树脂基质覆盖并保护。我们研究了单体与胶原在原子和分子水平上的相互作用在与HEMA混合时是否会受到影响。
我们进行了饱和转移差（STD）核磁共振光谱分析，以研究两种功能性单体，偏苯三酸4-甲基丙烯酰氧基乙酯（4-MET）和磷酸10-甲基丙烯酰氧基癸酯（MDP）与作为三螺旋肽模型的去端肽胶原的结合相互作用。通过向去端肽胶原溶液中添加4-MET或MDP来进行STD核磁共振测量。
当去端肽胶原饱和时，将MDP溶解于二甲基亚砜（DMSO）中时，在MDP光谱中检测到脂肪链中质子的STD信号。然而，当MDP与HEMA混合时，STD信号消失。无论是在DMSO中还是在HEMA混合样品中，4-MET配体样品均未观察到STD信号。
MDP与去端肽胶原的相互作用是疏水性的；然而，MDP-HEMA混合物可能在去端肽胶原溶液中形成聚集体，这会抑制MDP的疏水性。MDP-HEMA聚集体的形成可能会损害MDP与胶原的相互作用，使胶原纤维得不到MDP和HEMA的保护。单体与暴露的胶原之间不稳定的化学相互作用可能会破坏混合层的完整性以及与牙本质的强粘结性。
