Lysine dendron, which easily can be synthesized on hydrazine resins (Fmoc-hydrazono-pyruvyl-aminomethylpolystyrene resin, Product code: PYV1000). This Lysine core can be used for subsequent modifications. The hydrazide function will react with reactive aldehyde groups from synthetic or natural polymers, containing reactive aldehyde groups (e.g. oxidized N-terminal serine or threonine in the case of peptides). Then they can be applied for the design of gene delivery systems, changing of polymer surface properties, etc.). The conjugation process can be performed using hydrazone ligation approach with (or without) subsequent reduction of hydrazone bond by NaBH4. All necessary protocols can be supplied on request. Reference: Contrast Agents for Magnetic Resonance Imaging Based on Dendronized N-Vinylpyrrolidone Polymers; S.V. Burov, K.V. Polyanichko, P.S. Chelushkin, M.Yu. Dorosh, I.I. Gavrilova, A.V. Dobrodumov, Yu.V. Pokhvoshchev, V.D. Krasikov, E.F. Panarin; Doklady Chemistry 2016; 466: 18-20. DOI: 10.1134/S0012500816010055. Synthesis of dendronized polymeric chelating agents using hydrazone ligation strategy; Ksenia V. Polyanichko, Pavel S. Chelushkin, Marina Yu. Dorosh, Irina I. Gavrilova, Evgeny Panarin, Anatoliy V. Dobrodumov, Sergey V. Burov; European Polymer Journal 2017; 92: 117-125. .