DNA Condensation Of RGD Peptide Modified Polybenzimidazole Compounds

Gene therapy is a new medical technology that encompasses molecular biological methods to treat a disease by introducing the normal gene or the therapeutic gene into a patient’s cells. Therefore, designing effective gene carrier vectors that can protect and transfer exogenous gene into the target cells for gene therapy is a major challenge for gene delivery, while promoting the aggregation of DNA is a top challenge of the gene vector. RGD(Arg-Gly-Asp) motif on the extracellular matrix or cell surface, together with its integrin receptors, constitutesa major recognition system for cell adhesion. In this work, we chosed bis(benzimidazol-2-ylmethyl)amine (IDB), tris(benzimidazol-2-ylmethyl)amine(NTB) as primary materials, and based on which we synthesized two RGD motif covalently modified polybenzimidazole IDB-RGD and NTB-RGD as a targeting gene carrier. We systematically discuss the efficiency of the two compounds for gene delivery. The main results are as follows:Firstly, two RGD motif modified polybenzimidazole complexes IDB-RGD and NTB-RGD have been prepared and were characterized. Then, we found that the UV-vis absorption of the two gene carrier is different in different solvent (water and ethanol).Secondly, The affinity of each compound for metal ion (Co2+, Fe3+, Zn2+, Ca2+) was detected by UV-Visible absorption. The binding ratio and the stability constant Ks were fitted.Finally, The affinity of each compound for DNA was detected by UV-Visible absorption. The observed results showed that there is a good binding capability of IDB-RGD or NTB-RGD for DNA. It indicates that intercalation between the ligands of the bzim groups and base pairs of DNA may be the key force to drive the binding process. The conclusion was supported by the evidence provided by the exclusion assays of EtBr bound to DNA.The results also suggest that NTB-RGD has strong affinity for DNA than IDB-RGD. The property of condensates which formed at different conditions was examined by means of The condensation behavior of ctDNA induced by polybenzimidazole complexes was examined by EMSA at different condition. The results showed that the DNA condensation inducing by IDB-RGD, NTB-RGD happened respectively at pH3.0and2.5. Metal ions Co2+, Fe3+, Zn2+, Ca2+can promote the IDB-RGD and NTB-RGD cohesion DNA. As shown by RALS and DLS the size of the DNA condensate is significantly dominated by concentration of the reactant and incubation time. The DNA condensates are packed more and more compactly with prolonging incubation time or increasing complex concentration. Therefore, the stable condensates can be generated via an appropriate process.