Hydrogels are commonly used as biomaterials for applications in biomedicine due to their 

biocompatibility. However, the relationship between biological cells and the hydrogel surfac

e is still unclear and the existing parameters to explain the interactions are not sophisticated 

enough. In a recent study, Jooyoung Lee, Boa Song and co-workers at the Center for 

Biomaterials and the Department of Polymer Engineering in the Republic of Korea studied 

the impact of polymer chain flexibility on cell adhesion, with a variety of hydrogel constructs 

composed of the natural polymers collagen and fibrin.

They introduced a new method of semi-flexible, model-based analysis to confirm that chain 

flexibility mediated the hydrogel microstructure as a critical factor that allowed cell adhesion

 at the cell-material interface. The analysis proposed in the study is able to more accurately 

predict biocompatibility (cytocompatibility) of hydrogels. Results of the work now published 

in Scientific Reports, provide an important criterion for polymer design and development by 

enhancing biocompatibility and biofunctionalization at the cell-material interface for 

biomedical applications in vivo.

Hydrogels are made of polymer networks swollen with water and have applications in drug 

delivery  and  tissue  engineering.  Cell-material  adhesion  is  crucial  for  in  vivo 

biocompatibility and most studies have tested cell behavior by analyzing bulk stiffness of the 

materials composition. Nevertheless, communication between cells at the hydrogel surface 

remains to be accurately understood. The FDA approved natural polymers collagen and 

fibrin, provide excellent biocompatibility for biomedical applications. Also known as semi-

flexible polymers, they do not comply with models of flexible chain solutions or rigid-rod 

networks. The semi-flexible model allows the prediction of chain flexibility of polymer netwo

rks by experimentally scaling the elastic plateau modulus.

In the new study, Lee and Song et al. proposed a new, semi-flexible model-based analysis to 

understand cell adhesion to hydrogels using the well characterized collagen and fibrin 

polymers. They used three different collagen and fibrin constituents, to investigate the factors 

that determined cell adhesion: