Polyglycerol‐Based Mucus‐Inspired Hydrogels

The mucus layer is a hydrogel network that covers mucosal surfaces of the human body. Mucus has important protective properties that are related to its unique rheological properties, which are based on mucins being the main glycoprotein constituents. Mucin macromolecules entangle with one another and form a physical network that is instrumental for many important defense functions. Mucus derived from various human or animal sources is poorly defined and thus not suitable for many application purposes. Herein, a synthetic route is fabricated to afford a library of compositionally defined mucus‐inspired hydrogels (MIHs). MIHs are synthesized by thiol oxidation to render disulfide bonds between the crosslinker ethoxylated trimethylolpropane tri(3‐mercaptopropionate) (THIOCURE ETTMP 1300) and the linear precursors, dithiolated linear polyglycerol (LPG(SH)2) or polyethylene glycol (PEG(SH)2) of different molecular weights. The mixing ratio of linear polymers versus crosslinker and the length of the linear polymer are varied, thus delivering a library of compositionally defined mucin‐inspired constructs. Their viscoelastic properties are determined by frequency sweeps at 25 and 37 °C and compared to the corresponding behavior of native human mucus. Here, MIHs composed of a 10:1 ratio of LPG(SH)2 and ETTMP 1300 are proved to be the best comparable to human airway mucus rheology. A facile and cost‐effective synthetic approach based upon crosslinking of linear polyglycerol (LPG) dithiol with tri‐polyethylene glycol‐thiol affords synthetic hydrogel networks that show similar rheology to the human lung mucus. While in the latter the ideal elastic modulus is 1 Pa, the LPG‐based mucus‐inspired hydrogels are found to have an elastic modulus of 8 Pa, thus falling within the desired range.