Quantitative structural alterations of collagen dictate discoidin domain receptor 2 binding efficacy and CAL-27 cell adhesion behaviors.

Collagen specifically binds discoidin domain receptor 2 (DDR2) to regulate cellular behaviors such as adhesion and spreading. Although its molecular structure is highly susceptible to physicochemical modifications, the quantitative impact of these alterations on DDR2 engagement and downstream cellular responses remains poorly understood. Herein, we systematically investigated the effects of physical treatments including cryogenic milling, heating, and irradiation on the structural integrity of bovine Achilles tendon collagen and its subsequent DDR2 binding capacity. Structural parameters were quantified using circular dichroism and SDS-PAGE, and CAL27 squamous carcinoma cells were used as the cellular model. The affinity of collagen for DDR2 showed an exponential positive correlation with triple-helix integrity (R2 = 0.92) and an exponential negative correlation with molecular fragmentation (R2 = 0.96). Binding capacity also exhibited a strong linear correlation with CAL27 cell adhesion efficiency (R2 = 0.91). Progressive structural degradation significantly compromised cell adhesion, restricted cellular spreading, and downregulated surface DDR2 expression. This study provides a quantitative framework linking collagen structural parameters to DDR2 engagement and establishes exponential correlation models. These insights may inform the rational design of advanced collagen biomaterials and targeted receptor therapeutics.