Editing Synthesis of PEI Cho (section)

== Synthesis of Water Soluble PEI-Chol ==

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Dissolve 3 g PEI (1800 Da) in a ice-cold mixture of 10 ml anhydrous methylene chloride (Dichloromethane, DCM) and 10 ul triethylamine on ice for 30 min.

Dissolve 1 g Cholesteryl chloroformate in 5 ml methylene chloride on ice.

Add Cholesteryl chloroformate solution slowly to the PEI solution over 30 min

Stire the mixture for 12 h on ice.

Dry the resulting product on a rotary evaporator.

Dissolve the powder in 50 ml 0.1 N HCl.

Extract the aqueous solution with 100 ml methylene chloride to remove unreacted cholesteryl chloroformate

Filter through a glass microfiber filter.

Evaporate the solvent.

Dissolve the powder in water<br/>Precipitate three times with large excess acetone

Wash with methanol then three times with diethyl ether.

Dry under vacuum.







'''Method 2:'''

Add 30 mL of dehydrated chloroform to 100 μL dehydrated triethylamine<br/>Add 3 g of PEI<br/>place on ice

Stir for 30 minutes

Add 1 g cholesterol chloroformate dissolved in 10 mL chloroform at 0°C

stir overnight.

dissolve resulting yellowish viscous gel in 50 mL hydrochloric acid (0.1 mol/L).

Add 200 mL dehydrated chloroform to remove other polymers and cholesterol

filter through filter paper.

Repeat washing/extraction 2X<br/>freeze-dried --> a yellow powder.



'''Method 3.'''

Add 3&nbsp;grams of PEI (mw 1800) &nbsp;to a mixture&nbsp;of 10 mL of anhydrous methylene chloride and 100 µL of&nbsp;triethylamine, cool&nbsp;<span style="line-height: 20.8px;">on ice</span>&nbsp;for 30 min. 

Dissolve 1 gram of cholesteryl chloroformate&nbsp;in 5 mL of anhydrous ice-cold&nbsp;methylene chloride

Add <span style="line-height: 20.8px;">cholesteryl chloroformate solution</span>&nbsp;slowly (dropwise) &nbsp;to the PEI&nbsp;solution over&nbsp;30 min.

Stire the mixture for 12 h on&nbsp;ice.

Dry the reaction product&nbsp;on a rotary&nbsp;evaporator. 

Dissolve the powder in 50 mL of 0.1 N&nbsp;HCl and then filtered through the glass microfiber filter.

<br/>Cholesteryl chloroformate is well soluble in methylene&nbsp;chloride, diethyl ether, and acetone. Therefore, nonreacted&nbsp;cholesteryl chloroformate can be&nbsp;removed from the<br/>product by washing three times in these different organic&nbsp;solvents as follows: the aqueous solution is extracted&nbsp;three times with 100 mL of methylene chloride to remove<br/>nonreacted cholesterol chloroformate, and then extracted&nbsp;aqueous solution is filtered through a glass microfiber&nbsp;filter. The product is&nbsp;concentrated by solvent evaporation,<br/>precipitated with large excess acetone, and dried&nbsp;under vacuum. The powder is dissolved in water and&nbsp;precipitated three times with acetone. After washing with<br/>methanol, the product is washed three times with&nbsp;diethyl ether to yield&nbsp;white powder.

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