Editing Synthesis PolySpermine (section)

== Synthesis of polyspermine carbamate (PSP-Carb) and polyspermine amide (PSP-Amide)  ==

<br>Spermine (420 mg, 2.08 mmol) was dissolved in methanol (30 ml) at −78 ◦ C under a dry nitrogen atmosphere via Schlenk technique. Ethyl trifluoracetate (0.46 ml, 4.16 mmol) was then added dropwise and the resulting solution was magnetically stirred at 0 ◦ C for 1 h (Geall and Blagbrough, 2000). Protected spermine, N 1 ,N 14 -bis (trifluoracetyl) spermine, was isolated from this solution by evaporating the solvent and unreacted trifluoracetate. Then the<br>product was recrystallized in ethyl acetate with over 98% yield. Ethylenebis-(chloroformate) (144.0 mg, 0.77 mmol) or succinyl chloride(119.0 mg, 0.77 mmol) dissolved in chloroform (12 ml) was added dropwise to N 1 ,N 14 -bis (trifluoroacetyl) spermine (303.4 mg, 0.77 mmol) dissolved in chloroform (15 ml) and triethylamine (5 ml) at 0 ◦ C under a dry nitrogen atmosphere. The resulting solution was then continuously stirred at room temperature for 12 h (Xu et al., 2008). After the solvents evaporated, the reaction products were treated with a mixture of 30% ammonium water (1.4 ml) and methanol (8 ml) at 60 ◦ C in a sealed vessel for 8 h to remove the trifluoroacetate protecting groups (Garrett et al., 2000). The de-protected polyspermine biscarbamate (PSP-Carb) and bisamide (PSP-Amide) linkages were obtained after evaporating their respective liquid residues and dialyzed using a membrane with molecular weight cut-off (MWCO) of 3500 (Fig. 1). water and dialyzed through a cellulose membrane of molecular weight cutoff of 10000 (Thermo<br>Scientific) for 24 hours to remove the small fragments. The dialysate was stored at -80°C for 4 hours and<br>then freeze-dried (Christ Alpha 1-2 LD Freeze dryer, Germany) to obtain PSI (20 mg, 7.4&nbsp;% yield)<br> 

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The molecular weight (M w ) of PSI at the concentration of 2 mg/mL in water<br>measured by SEC relative to PEG standards was 21.9 KDa with polydispersity (PDI) 1.44.<br> 

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