Co-assembly of tetrapeptides into complex pH-responsive molecular hydrogel networks

Here we prepare pH-responsive complex molecular hydrogels from oppositely charged tetrapeptidic components that can be pH-tuned resulting in interconversion between different networks. Two different systems are described based on tetrapeptides with an alternating sequence of non-polar (F) and polar (D or K) residues. Co-aggregated hydrogels are easily formed in situ at neutral pH whereas one-component networks are maintained after changing into acidic or basic pH. These systems have been applied for the pH selective release of two hydrophobic dyes - Methylene Blue and Bromothymol Blue - as drug models. Different release profiles have been observed depending on the characteristics of the network as well as the pH of the media. These materials offer great potential as multidrug carriers.