The key components for successful resin-dentin bond involve a thin zone composed of polymerized methacrylate resin, demineralized type I collagen matrix, water, dentinal permeability, and enzymatic activity of endogenous enzymes. The aim is to identify a specific concentration of catechol-Lys-methacrylate (CLM) primer capable of improving the characteristics of this critical zone upon hydrothermal aging without interfering with adhesive cure. CLM preparation entailed the synthesis of a protected Lys--methacrylate intermediate followed by the incorporation of the catechol moiety and the removal of protecting groups using acidic conditions. Four different compounds including the final product CLM were synthesized in yields of 67.79\%, 93\%, 69\%, and 89\%, respectively. The presence of the methacrylate vinyl groups in CLM was confirmed by proton NMR in the range of 5.5--6.25 ppm. The disappearance of aromatic protons from the Fmoc protection group confirmed that acid cleavage occurred in the intermediate step prior to CLM synthesis. The presence of the final catechol and Lys protons was confirmed in the regions of 6.42--7.04 ppm and 2.73 ppm, respectively. Viability of human dental pulp cells following treatment with CLM, determined via median lethal dose, ranged between \SI{140}{\micro\gram\per\milli\liter} and \SI{160}{\micro\gram\per\milli\liter}. This value was consistent with UDMA and below that reported for Bis-GMA using the same exposure protocol. Dentin adhesion studies were performed using an etch-and-rinse procedure, utilizing Single Bond 2 after application of water or CLM solutions at a concentration of \SI{1}{\milli\gram\per\milli\liter}, \SI{5}{\milli\gram\per\milli\liter}, or \SI{10}{\milli\gram\per\milli\liter}. The parameters examined included adhesive conversion, microtensile bond strength in fresh and aged specimens exposed to 10,000 thermal cycles between \SI{5}{\celsius} and \SI{55}{\celsius}, scanning electron microscopy, silver nitrate nanoleakage test, in situ zymography, protein-ligand docking, attenuated total reflectance Fourier transform infrared (ATR--FTIR) spectroscopy, collagen mechanical testing, thermogravimetric analysis, dry mass loss, hydroxyproline leaching, and type IV collagenase inhibition.The primer concentration \SI{10}{\milli\gram\per\milli\liter} decreased degree of conversion, but the remaining \SI{1}{\milli\gram\per\milli\liter} and \SI{5}{\milli\gram\per\milli\liter} were both compatible with adhesive polymerization. With \SI{5}{\milli\gram\per\milli\liter}, the bond strength immediately and under thermal cycling was maximum. It also minimized the thermal-aging bond strength loss from 45.03\% for the control group to 17.54\%. The latter also maintained a relatively unbroken hybrid layer, generated the least amount of silver-tagged nanoleakages and lower collagenase enzyme activity within the bonding zone. The same phenomenon allowed for maintaining the integrity of the hybrid layer more consistently, generated fewer nanoleakages marked by the presence of silver, and had lower levels of collagenase activity in the region of bond. Docking studies of CLM with the collagen molecules 1QSU, 1CGD, and 4OY5 gave binding energy values of -3.83, -4.71, and -4.60 kcal mol$^{-1}$ respectively. Studies using ATR–FTIR and the collagen stability assay suggested direct interaction of CLM with demineralized dentine collagen. Among the tested concentrations, \SI{5}{\milli\gram\per\milli\liter} CLM provided the clearest balance between wet-interface adhesion, collagen protection, and resin-network formation.

resin--dentin adhesion,catechol,lysine,methacrylate primer,hybrid layer,nano leakage,collagen stabilization,wet bonding,thermocycling,type I collagen