Abstract
Self-assembled peptide hydrogels have emerged in recent years as the new paradigm in biomaterials research. We have contributed to this field the development of hydrogels based on dehydrodipeptides N-capped with naproxen. The dehydrodipeptide hydrogels can be loaded with drugs, thus being potential nanocarriers for drug delivery. In this work novel dehydrodipeptides containing tyrosine and aspartic acid amino acid residues N-capped with naproxen and C-terminal dehydrophenylalanine were prepared and characterized. Superparamagnetic iron oxide nanoparticles (SPIONs) were incorporated into the dehydrodipeptide-based hydrogels and their effect on the self-assembly, structure and rheological and magnetic properties of the hydrogels was studied. Magnetic hydrogels, with incorporated SPIONs, displayed concentration-dependent T2-MRI contrast enhancement. Moreover, upon magnetic excitation (alternating magnetic field –AMF–) the SPIONs were able to generate a significant amount of heat. Hence, magnetic hyperthermia can be used as a remote trigger for release of drug cargos and SPIONs incorporated into the self-assembled dehydrodipeptide hydrogels.
Highlights
Crystalline, single domain iron oxide nanoparticles, usually with core size between 4–18 nm, display superparamagnetism
Nanomaterials 2019, 9, 541 and co-workers demonstrated that a self-assembled peptide hydrogel, incorporating Superparamagnetic iron oxide nanoparticles (SPIONs) coated with hydrogelator molecules, displays typical magnetorheological behavior, i.e., a gel-sol transition trigged by a non-uniform magnetic field [28]
We can observe that the magnetization monotonically increases with the temperature down to 2 K, further pointing to a strong interacting magnetite nanoparticle system and highlighting the presence of significant dipolar magnetic interactions. This magnetically strong interacting-like behavior differs from the collective behavior observed in other magnetic nanoparticles-based systems, such as magnetite nanoparticles arrays and magnetic zeolites, where both ZFC and FC magnetization curves decrease below TB [43,44]
Summary
Crystalline, single domain iron oxide nanoparticles, usually with core size between 4–18 nm, display superparamagnetism. Magnetic hydrogels, based on synthetic and natural polymers, have been extensively reported in the literature as potential agents for magnetic field-activated hyperthermia and drug delivery [26,27]. Bing Xu. Nanomaterials 2019, 9, 541 and co-workers demonstrated that a self-assembled peptide hydrogel, incorporating SPIONs coated with hydrogelator molecules, displays typical magnetorheological behavior, i.e., a gel-sol transition trigged by a non-uniform magnetic field [28]. Cienfuegos and co-workers reported that the nanostructure and rheological properties of a peptide-based supramolecular hydrogel containing iron nanoparticles can be substantially improved by performing the self-assembly in the presence of a magnetic field [29]. The effect of SPIONs incorporation on the self-assembly and micro-nanostructure of the hydrogels and on their rheological and magnetic properties, as well as their efficiency as CA for MRI and heat source for magnetic hyperthermia, were studied. Preliminary data on the biological properties of the hydrogelators were collected as well
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