Effect of Divalent Metal Cations on the Conformation, Elastic Behavior, and Controlled Release of a Photocrosslinked Protein Engineered Hydrogel

This research was conducted by Jin Kim Montclare, Professor of Chemical and Biomolecular Engineering; and former students Yao Wang, a recent Ph. D. graduate, and Xiaole Wang, a former M.S. student.

Protein hydrogels are versatile 3-dimensional macromolecular structures with an astonishing variety of potential applications, many of them in medicine, including tissue engineering and wound healing. Because of their hydrophilic properties and internal architecture, these compounds can even trap and deliver drugs directly to targets, opening up a host of potential applications involving safe delivery of cytotoxic compounds that are standard treatment for cancer and other diseases.

To have such “Swiss Army Knife” capabilities, these typically soft materials must be imbued with properties conferring static and dynamic mechanical strength that enables them to carry a molecular payload and know when to release it.

Taking up this challenge, Montclare and her former students built upon recent work developing a photo-crosslinkable triblock copolymer protein hydrogel called CEC-D, a compound with limited viscoelastic mechanical and moderate sustained release properties. In the new work they explored the potential of transition metal cations (positively charged ions) to enhance the mechanical properties of CED-D, including its ability to encapsulate and release the small molecule curcumin, known for its anti-inflammatory properties.

In the paper, “Effect of Divalent Metal Cations on the Conformation, Elastic Behavior, and Controlled Release of a Photocrosslinked Protein Engineered Hydrogel,” published in the ACS publication Applied Bio Materials, the investigators found that the hydrogels coordinated with divalent metal ions such as Zn2+, Cu2+, and Ni2+ demonstrated control over the encapsulation and release of curcumin, a discovery suggesting that cation-tuned hydrogels constitute a promising drug delivery platform with tunable physicochemical properties.

“Depending on the metal, we can control the structure, mechanical stiffness and small molecule delivery of the hydrogel,” said Montclare. “This has important implications for drug delivery and this knowledge can be used to tailor vehicles to deliver specific therapeutics.  For example, we can tailor these materials to fabricate wound dressings that improve healing by triggering drug release in the presence of metals.”