Campus Units

Materials Science and Engineering, Chemical and Biological Engineering, Ames Laboratory

Document Type


Publication Version

Accepted Manuscript

Publication Date


Journal or Book Title

Biochemical Engineering Journal

First Page





Adhesion of macrophages to material substrates plays an essential role in many biological behaviors and biomedical procedures, including wound healing, cancer treatment and biomaterial implantation. Therefore, altering the adhesion of macrophages using biomaterial design may help control their biological function. In this work, we developed a straightforward method to render the hydrogel surface more hydrophobic and demonstrated that the adhesion of macrophages on hydrogels was enhanced on these more hydrophobic surfaces. Compared to the unmodified methacrylated gellan gum (MGG) hydrogel, the water contact angle increased and the swelling ratio decreased for modified MGG hydrogels. The degree of hydrophobicity was controlled by attaching hydrophobic branches of different lengths to the MGG, while the modification did not change the hydrogel compressive modulus. This ensured that the observed different cell responses were mainly due to hydrophobicity change and not the mechanical property difference among the hydrogels. Cell (RAW 264.7 macrophages) proliferation and spreading increased with increasing surface hydrophobicity. Protein adsorption on hydrogel surfaces showed the same trend. Quantification of adhesion to hydrogel surfaces using a hydrophobic probe showed that adhesion was enhanced as substrate hydrophobicity increased. This suggests that cell adhesion may be promoted due to the increase in hydrophobic adhesion that could enhance protein adsorption. In addition, tumor necrosis factor-α (TNF-α) secretion by lipopolysaccharide (LPS) activated M1 and interleukin-4 (IL-4) activated M2 macrophages was also altered by substrate hydrophobicity. TNF-α production, a marker of pro-inflammatory macrophages, decreased with substrate hydrophobicity. These results suggest that substrate hydrophobic can be used to modulate macrophage responses.


This is a manuscript of an article published as Xu, Zihao, Doh-Gyu Hwang, Michael D. Bartlett, Shan Jiang, and Kaitlin M. Bratlie. "Alter macrophage adhesion and modulate their response on hydrophobically modified hydrogels." Biochemical Engineering Journal (2020): 107821. DOI: 10.1016/j.bej.2020.107821. Posted with permission.

Copyright Owner

Elsevier B.V.



File Format


Available for download on Wednesday, October 05, 2022

Published Version