Degradable Hybrid Materials Based on Cationic Acylhydrazone Dynamic Covalent Polymers Promote DNA Complexation through Multivalent Interactions

Abstract

The design of smart nonviral vectors for gene delivery is of prime importance for the successful implementation of gene therapies. In particular, degradable analogues of macromolecules represent promising targets as they would combine the multivalent presentation of multiple binding units that is necessary for achieving effective complexation of therapeutic oligonucleotides with the controlled degradation of the vector that would in turn trigger drug release. Toward this end, we have designed and synthesized hybrid polyacylhydrazone-based dynamic materials that combine bis-functionalized cationic monomers with ethylene oxide containing monomers. Polymer formation was characterized by (1) H and DOSY NMR spectroscopy and was found to take place at high concentration, whereas macrocycles were predominantly formed at low concentration. HPLC monitoring of solutions of these materials in aqueous buffers at pH values ranging from 5.0 to 7.0 revealed their acid-catalyzed degradation. An ethidium bromide displacement assay and gel electrophoresis clearly demonstrated that, despite being dynamic, these materials are capable of effectively complexing dsDNA in aqueous buffer and biological serum at N/P ratios comparable to polyethyleneimine polymers. The self-assembly of dynamic covalent polymers through the incorporation of a reversible covalent bond within their main chain is therefore a promising strategy for generating degradable materials that are capable of establishing multivalent interactions and effectively complexing dsDNA in biological media.

Constitutional Dynamic Materials—Toward Natural Selection of Function

“…151 DCFs 24 are relevant in biological and medicinal research, especially when the biotargets, like DNA, contains a large number of members. Multifunctional core centers, linear poly(ethylene glycol) (PEG) macromonomers, and cationic heads have been used to generate DCFs for DNA binding ( Figure 52).…”

Synthetic multivalency for biological applications

“…Such approaches to optimal display discovery are only beginning to develop. [130][131][132] These systems display the property of dynamic reversible component rearrangement at the molecular level, so adapting surface through supramolecular interaction with the target DNA and the cell membrane barrier. Many effective non-viral vectors have been rationally designed in recent decades.…”

Photomodulation of DNA‐Templated Supramolecular Assemblies

“…This positive ICD signal shows a maximum intensity at a molar ratio around 1:50 in dT 40 /Gua‐Azo (Figure S15), showing that the Gua‐Azo trans adopts a chiral organisation upon DNA binding. Note that ICD signals of ligands upon DNA binding were previously reported for other guanidinium derivatives, including GuaBiPy, for which the maximum ICD is around 1:20 in dT 40 /GuaBiPy (single‐stranded DNA template) . The same experiments were repeated on double‐stranded DNAs (dsDNA), a duplex oligonucleotide (dsR 20 ) and a long dsDNA (stDNA).…”

“…To further assess the effect of photoisomerisation over the self‐assembly of Gua‐Azo/GuaBiPy along the DNA template, fluorescence spectroscopy was carried out, as the pyrene moieties are efficient fluorescent probes to assess DNA‐templating effects. It was previously observed in the emission spectra that excimer emission GuaBiPy (maximum at around 470 nm) is favoured at the expense of monomer emission (peaking at 396 nm) upon interaction with single‐stranded DNA, indicative of pure GuaBiPy templated self‐assembly, stabilised by π‐stacking of pyrenes ,…”