Sequence-Defined Polymerization Via Tandem Multicomponent Reactions&Polyphosphonium For Gene Delivery

Multicomponent polymerizations have become a powerful tool for constructing sequence-defined polymers now. Though Passerini multicomponent reaction has been widely used in sequence-defined polymer synthesis, the utilizations of tandem Passerini multicomponent reaction and other multicomponent reaction in one-pot for the syntheses of sequence-defined polymers have not been developed till now. In this contribution, we report tandem Passerini three-component reaction and the three-component reaction of amine-thiol-ene conjugating in one-pot for sequence-defined polymer synthesis, in which Passerini reaction of methacrylic acid, adipaldehyde and2-isocyanobutanoate were carried out, giving a new molecule containing two alkene unit. Subsequently, amine and thiolactone were added into the reaction system, the three-component reaction of amine-thiol-ene conjugating occurred, yielding a sequence-defined polymer, which has a molecular weight of13.7kDa and a polydispersity of3.1. Moreover, these tandem three-component reactions can be extended to prepare sequence-defined polymers with functional side units (such as a clickable alkene unit). The functional polymer has a molecular weight of49.8kDa and polydispersity of2.03after a reaction time of48h, and other groups can be linked onto the functional polymer via post-modification. This method would offer a more rapid access to construct sequence-defined polymers with highly molecular diversity and complexity.Simultaneously, topologic structures of polymers can also influence the properties of materials. The structure and sequence of biomacromolecules are closely associated with the vital life activities, and the mutation of gene sequence can cause serious genetic diseases. Now nonviral gene therapy focuses nitrogen-containing polymers and lipids to deliver DNA as a therapeutic for these genetic human diseases. And the treatment effect of polycation gene vectors can be significantly affected by their topologic structures. Here, we synthesized various structures of phosphonium-containing polymers via RAFT polymerization as new gene vectors. Dynamic light scattering (DLS) assays indicated that the synthesized poly[tributyl-(4-vinylbenzyl)phosphonium]s (PTBP) can form positive nanoparticles (zeta-potential above+25mV) in～100nm size with DNA. And DNA gel shift assays revealed PTBP can bind DNA tightly at low charge ratio (2/1), the formed polyplexes were more stable than PEI/DNA polyplexes in heparin solution. Luciferase expression assay indicated that PTBP/DNA polyplexes at low charge ratio can efficient delivery DNA into Hela cells similar to PEI (N/P=10). Within the various structures of PTBP, the linear one expressed the best gene transfection. And, as the increasing of brahching degree, the transfection of PTBP declined. Simultaneously, polyphosphonium exhibited much toxicity in cells, so it needs more modifications and researches on phosphonium-containing polymers for gene delivery.