Fourier transform microwave spectra in the 6-20 GHz region are obtained for the complex formed between 1,1,2-trifluoroethylene and hydrogen chloride, including both (35)Cl and (37)Cl isotopomers. Analysis of the spectra provides rotational constants and additionally, the complete quadrupole hyperfine coupling tensor in both the inertial and principal electric field gradient axis systems. The inertial information contained in the rotational constants combined with the results of the hyperfine analysis provides the structure for CF(2)CHF-HCl. A primary, hydrogen bonding interaction exists between the HCl donor and the F atom geminal to the H atom on the substituted ethylene. The hydrogen bond is bent from linearity to allow a secondary interaction to form between this H atom and the Cl atom. Comparisons made to similar complexes involving both other protic acids (HF and HCCH) and fluoroethylenes (vinyl fluoride and 1,1-difluoroethylene) reveal the effects of varying gas phase hydrogen bond donor strength, of increasing fluorine substitution on fluorine atom nucleophilicity, and on the relative importance of steric versus electrostatic effects in determining the structures of these species.
Endogenous dentinal matrix metalloproteinases (MMPs) have been implicated in the auto-degradation of collagen fibrils within resin infiltrated layers of dentinal attachment. In order to target these proteinases, we must know which MMPs are produced and activated at the resin/dentin interface. In this study, we have optimized an extraction procedure and quantitated levels of endogenous MMPs in samples of dentin removed from the cavity walls of a single, extracted tooth. In our tooth-cavity model, an occlusal cavity (2×4×2 mm) was prepared and removed from the tooth crown, leaving surrounding dentinal walls of 1-mm-thick. The samples were pulverized with an analytic mill. Using enzyme-linked immunosorbent assay (ELISA), an average of 34.7 picograms of MMP-9 was detected in less than 300 mg of dentinal powder. This is the first study of its kind to quantitate endogenous levels of MMP in dentinal protein isolated from the cavity walls of a single, extracted tooth.
Inhibition of matrix metalloproteinase (MMP) activity is expected to increase the long‐term stability and durability of resin‐based restorations by preventing degradation of denuded collagen fibrils in the hybrid layer. Endogenous MMP‐8, released by adhesive procedures, can hydrolyse collagen fibrils at resin/dentin interfaces compromising adhesive bond durability. In this study, occlusal surfaces of n=4 extracted non‐carious human molar teeth (<2 days from extraction, stored −80°C) were removed using a low‐speed diamond saw. 2×4×2mm cavity was prepared on the dentinal surface, leaving surrounding dentinal walls of 1mm thickness. Cavity walls were then acid‐etched with 38% phosphoric acid, pulverized using a liquid nitrogen analytic mill, demineralized in 1% phosphoric acid, suspended in extraction buffer (100mM Tris‐HCl pH 7.6, 0.1mM ZnCl2, 100mM CaCl2, 200mM NaCl, 1% Triton X‐100) and centrifugally concentrated. The results of our study showed that an average of 0.238pg MMP‐8/mg dentin is present as measured by ELISA. This study is the first of its kind to identify endogenous levels of MMP‐8 present in a single‐tooth dentin sample. This information will contribute to the design of specific, clinical inhibition of endogenous MMP activity in dentinal cavity walls to prolong the longevity of resin‐based restorations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.