Engineering Bonding Types and Macromeric Cross-Linkers in the Network To Modulate the Structures and Properties of Polydextran/Chitosan Hybrid Hydrogels

Hybrid hydrogels are versatile biomaterials, and cross-linkers are the key for tailoring their characteristics. However, the bonding types in the network and the hydrophobic chain lengths of cross-linkers remain underexplored. This study introduces formylbenzoic acid-modified PEG (PEG-FA), which further reacts with adipic acid (AA), sebacic acid (SA), and tetradecanedioic acid (TDA) to create cross-linkers with varying hydrophobic segments. PEG-FA and its derivatives are used as aldehyde-functionalized macromeric cross-linkers to react with polydextran hydrazide (PDH) and quaternized chitosan (QCS) to form PDH/QCS hybrid hydrogels through dynamic interactions. The results indicate that increasing the hydrazone/imine ratio improves the strength and stability of the network. Notably, TDA-PEG-FA cross-linkers grant hydrogels with smaller pores and better mechanical strength. Overall, the structures and properties of PDH/QCS hydrogels can be tailored by selecting bonding types and designing macromeric cross-linkers in the network, enabling the customization of hydrogel performance for advanced applications.