Procedure for transferring biomolecule into a cell, comprises preparing a complex from the biomolecule, preferably nucleic acid, and a polymer, which is obtained through reacting an amine-monomer exhibiting at least two amine group with an epoxide monomer exhibiting at least two epoxide groups； and transferring the biomolecules into a cell by contacting the cell with the complex. Independent claims are included for: (1) a kit for transferring a biomolecule into a cell comprising a polymer； and further kit components； (2) a complex comprising a biomolecule, preferably nucleic acid, and a polymer； (3) a therapeutic composition, comprising a biomolecule and a polymer； and (4) a method for the treatment of disease by gene therapy comprising drafting a cell from an organism； transferring the biomolecule into a cell by the above procedure； and restoring the cell into an organism.
