Being closely associated with a variety of physiological and pathological processes, matrix metalloproteinases (MMPs) are useful as potential targets for drug therapy and informative markers for disease diagnosis. On the basis of the electrochemically induced grafting of ferrocenyl polymers and the proteolytic cleavage of recognition peptide, a novel electrochemical sensor is presented in this work for the highly specific interrogation of MMP activities at ultralow levels. The recognition peptide, to be immobilized via the N-terminus, is free of carboxyl group. The presence of the target MMP would cleave the end-tethered recognition peptide, generating a free carboxyl group at the C-terminus of the rest fragment. To be used as the reversible addition−fragmentation chain-transfer (RAFT) agent, the dithiobenzoate, 4-cyano-4-(phenylcarbonothioylthio)pentanoic acid (CPAD), can therefore be tethered via the carboxylate-Zr(IV)-carboxylate chemistry. Subsequently, the grafting of ferrocenyl polymers through electrochemically induced RAFT (eRAFT) polymerization of ferrocenylmethyl methacrylate (FcMMA) would recruit a large quantity of Fc redox reporters on electrode surface . With benefits from the excellent specificity of the enzyme-substrate recognition, the presented cleavage-based sensor is highly selective. Under optimal conditions, the detection limit in the presence of MMP-2 as the model target can be as low as 0.27 pg mL −1 , with a linear range from 1 pg mL −1 to 1 ng mL −1 . Furthermore, its applicability in the interrogation of MMP activity in complex serum samples and the screening of MMP inhibitors is satisfactory. The presented cleavage-based electrochemical MMP sensor is easy to fabricate and low-cost, thus showing great promise in drug discovery and disease diagnosis.
Objectives 10-Methacryloyloxydecyl dihydrogen phosphate (MDP) has been regarded as the most effective dentin-bonding monomer for more than 20 years. Although the dentin-bonding promoting effect of MDP has been well demonstrated, the mechanisms by which it benefits the stably of collagen within the adhesive–dentin hybrid layer are not currently fully understood. The objective of this study was to investigate the roles of MDP and its calcium salt in preserving the adhesive–dentin hybrid layer. Methods MDP-conditioned collagen was investigated by Fourier-transform infrared spectroscopy, Ultraviolet–visible spectroscopy, and molecular docking. The structural changes to the dentin surface upon acid-etching and MDP-conditioning were observed by SEM. X-ray diffraction and nuclear magnetic resonance were used to investigate the chemical interactions between MDP and HAp. The collagen-protecting effects of MDP and its Ca salt were investigated using in-situ zymography, rhMMP-9 colorimetric assay, hydroxyproline assay, and molecular docking. Results MDP forms a stable collagen-phosphate complex through hydrogen bonding with the collagen in dentin. Furthermore, it generates MDP-Ca salts that are deposited on the dentin collagen scaffold, protecting it from degradation. Moreover, both free MDP and the MDP-Ca salt inhibit matrix metallopeptidase and exogenous proteases, with the inhibitory effect of the calcium salt being significantly stronger than that of the free form. Significance MDP-based adhesives preserve the collagen within the hybrid layer by simultaneously improving collagen’s resistance to exogenous enzymes and inhibiting MMP activity, both of which contribute to the longevity of dentin–resin bonding.
危险品化学品经营许可证（带存储）