Investigations of Self-Assembling Guanosine Phosphoramidate Based Hydrogels

Abstract

Peptides and nucleobases are supramolecular building blocks that have been widely investigated for their self-assembling properties and ability to form supramolecular structures. These high-aspect ratio structures eventually form entangled matrices that result in supramolecular hydrogels. Previous work in our lab incorporated enzymatic activity in the regulation of peptide self-assembly, where we investigated Histidine Triad Nucleotide Binding Protein 1 (Hint1) as a modulator of supramolecular self-assembly.1 In this work, we developed a panel of self-assembling nucleoside phosphoramidates (SANPs) capable of Hint1 triggered hydrogelation. SANPs are low molecular weight molecules that incorporate a self-assembling peptide conjugated to a nucleoside phosphoramidate group through a short PEG linker. A surprising observation in the development of these Hint1 responsive molecules was the spontaneous assembly of the SANPs into highly ordered nanofibers without enzymatic activity, and the unique ability of the guanosine SANPs to form supramolecular hydrogels.Guanosine and its derivatives have been of particular interest for researchers due to its unique ability to form G-quadruplexes that drive self-assembly, but their instability and tendency to precipitate from solution have limited the applications of these biomaterials. Herein, we report the unique interplay of two self-assembling moieties to drive supramolecular hydrogelation: an ultrashort self-assembling peptide and a guanosine nucleobase. This body of work details the fundamental investigation of our panel of SANPs and the influence of nucleobase identity on the critical aggregation concentration, stability, and hydrogelation ability of these molecules. Specifically, we examine the synergistic self-assembly of the guanosine SANPs and tease out the interactions that ultimately result in supramolecular hydrogelation. Characterization of these dual moiety guanosine SANPs reveal that the resulting hydrogels integrate principal properties of both supramolecular building blocks, resulting in a novel biomaterial that addresses the caveats of the traditional guanosine-based hydrogels. We further examined their innate biological activity and demonstrate the promising application of these novel biomaterials for controlled drug release with the potent chemotherapeutic Doxorubicin and assess the activity of our drug depot in vitro.