In this paper the authors evaluate 4 types of hydrogels based on 2-hydroxyethyl methacrylate, which differ in their surface charges. They find that hydrogels with surface charges improve cellular adhesion and axonal ingrowth compared to hydrogels with no surface charge.
Further,hydrogels with positively charged surfaces improve the ingrowth of axons into the central parts of the bioimplants compared to hydrogels with negative charges.