Reinforcement of nanostructured polyacrylamide hydrogels through the generation of secondary physical network using the nanoparticles’ functional groups

Abstract

The main drawback regarding hydrogels utilization in biomedical engineering is represented by their weak mechanical properties and it is often addressed either by using nanospecies as fillers or by generating secondary networks that strengthen the material. Our study validates a new synthesis route of obtaining double-network nanostructured materials making use of the functional groups of an adsorbed glyco-protein on carbon-based nanospecies. Following a simple procedure, the decorated nanospecies were embedded in a synthetic polymer and subsequently formed a secondary hydrogen-bond based network through incubation in natural polyphenol solutions of various concentrations. The natural macromolecule's adsorption was evaluated through FTIR and DLS measurements. When compared to the single-network nanostructured materials, the double-network hydrogels exhibited lower affinity to aqueous media and improved ability to dissipate energy upon mechanical stress, depending on the amount of the employed natural crosslinker. As a result of generating the second network through incubation in polyphenol aqueous solution, the surface storage and loss moduli exceed the values of the bulk ones, as indicated by rheology and nanoindentation tests. The properties of the double-network hydrogels can also be tailored towards more hydrophilic surfaces with increased roughness through the control of the supplementary crosslinker amount. Considering the studied physical-chemical properties, and especially their mechanical characteristics, the obtained materials hold great promise for biomedical applications, particularly for the fabrication of scaffolds for wound dressing, soft or low load bearing tissue regeneration and repair.