Polymeric carrier molecule of formula (I): L-P1-S- [S-P2-S] nS-P3-L where, P1 and P3 are identical or different and represent a linear or branched hydrophilic polymer chain, having each P1 and P3 at least one part -SH capable of forming a disulfide bond under condensation with a P2 component, the branched or linear hydrophilic polymer chain being selected independently from among polyethylene glycol (PEG), poly-N- (2-hydroxypropyl) methacrylamide, poly-2 - (methacryloxy) ethylphosphorylcholine, poly (hydroxyalkyl-L-asparagine), poly (2- (methacryloxy) ethyl-phosphorylcholine), hydroxyethylamidmid or poly (hydroxyalkyl-L-glutamine), where the hydrophilic polymer chain has a molecular weight of 1 kDa At 100 kDa, P2 is a cationic or polycationic peptide or protein, and is 3 to 100 amino acids in length, or is a cationic or polycationic polymer with a molecular weight of 0.5 kDa to kDa, each P2 having at least two -SH parts capable of forming a disul bond furo under condensation with additional P2 components or with P1 and / or P3 components； -S-S- is a disulfide bond； L is an optional ligand that may or may not be present, and which may be independently selected from GDPR, transferrin, folate, a signal peptide or a signal sequence, a signal or location sequence, a signal or nuclear localization sequence (NLS), an antibody, a cell penetration peptide, TAT, a receptor ligand, cytokines, hormones, growth factors, small molecules, carbohydrates, mannose, galactose, synthetic ligands, small molecule agonists, receptor inhibitors or antagonists, or analogues of RGD peptidomimetic； and n is an integer, selected from a range of 1 to 50, preferably in a range of 1, 2, 3, 4 or 5 to 10, most preferably in a range of 1, 2, 3 or 4 to 9 and where any of the P2 components may be the same or different, and where at least one additional amino acid component (AA) x is present or absent in the polymeric carrier molecule, where AA is an amino acid and x an integer selected from a range of
