Agarose-based hydrogels with tunable, charge-selective permeability properties

Physiologically, a hallmark of biological hydrogels is their ability to selectively trap diffusing molecules and particles. And indeed, there is now increasing interest in using selective hydrogel barriers for applications in biomedicine and medical engineering. However, when employing synthetic polymers to create hydrogels with selective permeabilities, controlling the type and strength of the ensuing filtration process is difficult. Here, we generate hybrid gels with adjustable selectivity profiles by mixing a series of (bio-)macromolecules with agarose. Depending on the type and concentration of the incorporated macromolecules, those hybrid gels achieve a selective retardation of the diffusive translocation of either positively or negatively charged dextrans at both, acidic and neutral pH. Furthermore, we demonstrate three strategies that provide hydrogels with sequestered patches of both, cationic and anionic binding sites, thus creating symmetric charge (i.e., electrostatic bandpass) filters which still allow neutral molecules to pass. Moreover, such agarose matrices offer a high level of versatility as their permeability profiles can be tailored at will by integrating macromolecules with desired physico-chemical properties. Thus, those agarose-based hybrid gels may serve as a powerful platform to engineer adjustable and versatile materials for a broad range of future applications in the field of biomedical engineering.