Electro-responsive hydrogels: macromolecular and supramolecular approaches in the biomedical field

Hydrogels are soft materials of the utmost importance in the biomedical and healthcare fields. Two approaches can be considered to obtain such biomaterials: the macromolecular one and the supramolecular one. In the first, the chemical gel is based on crosslinking while in the second the physical hydrogel is stabilized thanks to noncovalent interactions. Recently, new trends rely on smart devices able to modify their physico-chemical properties under stimulation. Such stimuli-responsive systems can react to internal (i.e. pH, redox potential, enzyme, etc.) or external (i.e. magnetic field, light, electric field, etc.) triggers leading to smart drug release and drug delivery systems, 3D scaffolds or biosensors. Even if some stimuli-responsive biomaterials are currently widely studied, other ones represent a real challenge. Among them, electro-responsive hydrogels, especially obtained via supramolecular approach, are under-developped leaving room for improvement. Indeed, currently known macromolecular electro-responsive systems are reaching some limitations related to their chemical composition, physicochemical properties, mechanical strength, processing technologies, etc. In contrast, the interest for supramolecular hydrogels has risen for the past few years suggesting that they may provide new solutions as electro-responsive soft materials. In this short review, we give a recent non exhaustive survey on macromolecular and supramolecular approaches for electro-responsive hydrogels in the biomedical field.