Generally, a 10 to 50-fold molar excess of NHS PEG over the amount of amine-containing material results in sufficient conjugation.

Materials Required:

• Conjugation buffer: Sodium bicarbonate 100 mM buffer, pH 8.5 or other amine-free buffer at pH 7-8.5.
• PEG NHS stock solution: 100 mg in 1 mL conjugation buffer.
• Washing solution: Distilled water or any aqueous buffer.

Reaction Steps:

Dissolve targeted materials in conjugation buffer. Estimate the concentration of primary amine groups on the targeted materials. Add NHS PEG stock solution to the targeted conjugation materials with the final concentration keep at least 10 mg/mL. 10~50 molar excess of PEG NHS needed for optimal conjugation; Allow mixture agitates at room temperature for 30~60 min at room temperature or 2 hours at 4 ⁰C. Conjugates can be purified either by size exclusion chromatography or dialysis.