The water soluble zinc based metal-organic frameworks (Zn-MOFs) as potential inhibitors for collagen fibrillogenesis

Small molecules ranging from organic to inorganic systems have been reported as stabilizing agents for collagen. Various transition metal complexes have been utilized as tanning agent. However, as per the environmental norms issued by various regulatory agencies, the presence of certain metals such as Cr, Fe, Al, Zr and Ti in leather has been restricted to minimal amount (50 ppm), an unsurmountable task. To overcome the above issue and find an alternative tanning system, here in this study, we have reported the interaction of two water-soluble zinc-based metal-organic frameworks (MOFs), i.e., ZnPV (1) and ZnPA (2), with collagen using various spectroscopic techniques. Fibrillation kinetics studies showed that a significant delay in fibril formation with Zn-MOFs treated collagen was observed compared to the collagen untreated/ treated with individual ligands and metal salt. Circular dichroism studies show that at a low weight ratio (1:0.2 and 1:1::Collagen: MOF), no perturbation in the triple helical structure was observed, while at higher weight ratio (1:4), denaturation of collagen occurs. FT-IR studies showed that no perturbation was observed in the amide backbone in MOF-treated collagen. Differential scanning calorimetric data revealed that both Zn-MOFs increased the thermal denaturation temperature by 22 ± 2 °C compared to the collagen treated with individual entities. The viscosity of collagen rises with the increase in the concentration of Zn-MOFs. To the best of our knowledge, this is the first report on the use of the metal-organic framework as a stabilizing agent for collagen structure and might help in exploring the MOFs as potential tanning agents.