Editing Synthesis PolySpermine (section)

== Polyspermine Imidazole-4,5-imine<br>  ==

'''Imine Structure'''<br>

[[Image:Imine_General_Structure.png]]<br>

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[[Image:Synthesis of PSI.jpg]]<br> 

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[[Image:PSI transfection efficiency.jpg]]<br> 

The synthesis of PSI was as simple as a single condensation reaction (Scheme 1): adding an approximately equivalent molar amount of imidazole-4,5-dialdehyde to spermine (both dissolved in dimethyl formamide (DMF)) in the presence of a catalytic amount of p-toluenesulfonic acid lead to the<br>formation of PSI. The polymerization was allowed to proceed at 80 8C for 24 h, with stirring, followed by filtration, evaporation, and dialysis in ultrapure water through a cellulose membrane (10 kDa molecular weight cut off). The final product was lyophilized to give a yellowish powder, prior to storage at -80 oC.<br><br> 

the average molecular weight (MW) of PSI was determined to be 21.9 kDa (with polydispersity of 1.44) by eluting a solution of the polymer (2 mg mL/1 in water) through an SEC column (PL aquagel-OH), using a series of polyethylene glycol (PEG) standards and 25 kDa polyethylenimine (PEI) for calibration.<br> 

Synthesis and characterization of polyspermine imidazole-4,5-imine (PSI)<br>Spermine (170 mg, 0.84 mmol) was dissolved in DMF (5 mL), to which p-Toluenesulfonic acid<br>monohydrate (1 mg, 0.005 mmol) and a small amount of freshly activated molecular sieves of type 4A<br>were added at room temperature under a high-purity nitrogen atmosphere. 1H-Imidazole-4,5-<br>dicarboxaldehyde 1 (100 mg, 0.8 mmol) dissolved in DMF (5 mL) was added dropwise to the mixture<br>slowly over 4 hours, and heated quickly to 80°C. After stirring for another 24 hours, the resulting solution<br>was filtrated in vacuum and evaporated to remove the solvent. The viscous residue was dissolved again in<br>