Characterization of the effects of bridging linker on the β-Lactoglobulin binding mechanism on the nanoscale metal-organic frameworks.

Revealing the interaction modes between nanoscale metal-organic frameworks (NMOFs) and food matrix is crucial for functional release but it still remains largely unknown to date. This study specifically focused on the milk protein adsorption mechanism of NMOFs using UiO66/UiO66-NH and β-lactoglobulin (β-LG) as models. UiO66 and UiO66-NH quenched the fluorescence of β-LG via static mechanism. Due to the enhanced electrostatic forces caused by NH, UiO66-NH-β-LG (2.83 × 10 mol·L) exhibited higher binding constant than UiO66-β-LG (2.61 × 10 mol·L), while UiO66 with higher hydrophobicity adsorbed more β-LG. The defects of UiO influenced the binding sites on the β-LG, and the higher the defect degree, the higher the binding energy. For the stability of the system, the H-bonding between UiO66 and SER30/PRO38, and the hydrophobic interaction between UiO66-NH and LYS101 played important roles. Furthermore, the secondary structure content of β-LG changed after interacting with both UiO, resulting in reduced density of β-LG.