Glutaraldehyde Coupling to PE Lipid Derivatives

Liposomes containing PE residues can be reacted with glutaraldehyde to form an activated surface possessing reactive aldehyde groups. A 2-step glutaraldehyde reaction strategy is probably best when working with liposomes, since precipitated protein would be difficult to remove from a vesicle suspension. 

Prepare a liposome suspension, containing PE, at a total-lipid concentration of 5mg/ml in 0.1M sodium phosphate, 0.15M NaCl, pH 6.8. Maintain all lipid-containing solutions under an inert gas atmosphere. Degas all buffers and bubble them with nitrogen or argon prior to use. 

Add glutaraldehyde to this suspension to obtain a final concentration of 1.25 percent. 

React overnight at room temperature under a nitrogen blanket. 

Purify the activated liposomes from excess glutaraldehyde by gel filtration (using Sephadex G-50) or by dialysis against PBS, pH 6.8. 

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