Functional monomers in adhesive systems can improve bonding by enhancing wetting and demineralization, and by chemical bonding to calcium. This study tested the hypothesis that small changes in the chemical structure of functional monomers may improve their bonding effectiveness. Three experimental phosphonate monomers (HAEPA, EAEPA, and MAEPA), with slightly different chemical structures, and 10-MDP (control) were evaluated. Adhesive performance was determined in terms of microtensile bond strength of 4 cements that differed only for the functional monomer. Based on the Adhesion-Decalcification concept, the chemical bonding potential was assessed by atomic absorption spectrophotometry of the dissolution rate of the calcium salt of the functional monomers. High bond strength of the adhesive cement corresponded to low dissolution rate of the calcium salt of the respective functional monomer. The latter is according to the Adhesion-Decalcification concept, suggestive of a high chemical bonding capacity. We conclude that the adhesive performance of an adhesive material depends on the chemical structure of the functional monomer.

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Since complement activation is recognized as a common response of the host defense system when an artificial medical device is applied to a patient, great effort has been devoted to studies on the interaction of the complement system with artificial materials. However, some uncertainties remain, partially because of the lack of well characterized surfaces and suitable analytic methods for study of the surface phenomena that occur on artificial materials under physiologic conditions. In this study, we employed self-assembled monolayers (SAMs) and the surface plasmon resonance (SPR) technique to study interactions of the serum complement with well characterized surfaces. Self-assembled monolayers carrying various concentrations of hydroxyl groups were prepared using 11-mercapto-1-undecanol (C11-OH) and one of n-nonanethiol, n-dodecanethiol, and n-hexadecanethiol. The amount of NHS deposition on the SAMs increased with increasing C11-OH content of the SAMs, and the amount of anti-C3b antibody immobilization formed on the NHS deposition layers increased with increasing C11-OH content of the SAMs. These results clearly demonstrate that a large amount of C3b, produced through the activation of the complement system, binds covalently to and is adsorbed by hydroxyl-group-rich surfaces. The combination of SAMs and the SPR technique is suitable for studying the interaction of the complement system with solid surfaces, and the results should give basic information needed for a rational design of biocompatible surfaces on synthetic materials.

Much attention has been directed to the development of sophisticated membranes that can regulate the permeability in response to environmental changes. In this study, pH-sensitive membranes were prepared by grafting of poly(acrylic acid) (PAAc) onto a porous Nuclepore membrane. The filtration rate of a membrane with a PAAc graft density of 0.30 µg/cm 2 was 28 times higher at pH 2.4 than at pH 5.4. Atomic force microscopy (AFM) was employed to make clear how the PAAc graft chains regulate the filtration rate. The thickness of PAAc graft layers was determined from the force curve in buffered solutions of various pHs. It was found that the graft layer thickness was several tens of nanometers at pH 2.6 and increased to 20-430 nm at pH 7.6, depending on the PAAc graft density. The PAAc chains grafted on the membrane surface dynamically changed their configuration in response to the medium pH. In addition, AFM images demonstrated that the graft chains shrank and precipitated on the surface of the membrane and the wall of pores at acidic pHs, thereby opening the pores of the membrane, whereas they hydrated and thus effectively closed the pores at neutral and alkaline pHs. The hydrodynamic permeation in conjunction with AFM observation of the graft layers allowed us to conclude that the PAAc graft chains dynamically opened and closed the pores in response to the medium pH, functioning as a molecular valve to regulate the permeation characteristics.

Each dental adhesive contains a specific functional monomer that determines its actual adhesive performance to tooth tissue. 4-methacryloxyethyl trimellitic acid（4-MET）is well-known as one of the functional monomers mostly available and consequently widely used in commercial adhesives. We therefore characterized the chemical interaction of 4 -MET with hydroxyapatite（HAp）using X-ray Photoelectron Spectroscopy（XPS） . XPS revealed that the peak representing -COO-of 4-MET shifted to a lower binding energy, when 4-MET was adsorbed onto HAp. Deconvolution of this shifted peak disclosed two components with a peak representing unreacted carboxyl groups and ester groups, and a peak suggesting chemical bonding of other carboxyl groups to Ca of HAp. XPS spectra of HAp treated with 4-MET also disclosed the surface to be enriched in calcium and decreased in phosphorus, indicating that phosphorus was extracted at a relatively higher rate than calcium. It can thus be concluded that true chemical bonding of 4 -MET with calcium present in HAp occurred, as it was proven using XPS.

We have previously reported that an osteopontin-derived SVVYGLR peptide exhibited potent angiogenic activity in vitro and in vivo. In the present study, the focus points were on the in vitro effect of SVVYGLR on bone marrow stromal cell proliferation, as well as its in vivo effect on bone tissue formation when grafts made of CO3 Ap-collagen sponge -as a scaffold biomaterial containing the SVVYGLR motif -were implanted. SVVYGLR peptide promoted bone marrow stromal cell proliferation. When a CO3 Ap-collagen sponge containing SVVYGLR peptide was implanted as a graft into a tissue defect created in rat tibia, the migration of numerous vascular endothelial cells -as well as prominent angiogenesis -inside the graft could be detected after one week. These results thus suggested that our scaffold biomaterials including the peptide could be useful for bone tissue regeneration.