Liposomes glutaraldehyde

Figure 22.23 Glutaraldehyde activation of PE-containing liposomes may be used to couple protein molecules.

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. 

The following protocol describes the 2-step method wherein the liposome is glutaraldehyde-activated, purified away from excess crosslinker, and then coupled to a protein by reductive amination (Figure 22.23). 

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

It is an important subject to develop an oxygen carrier as an artificial blood. There are several methods to construct artificial bloods. The first method is to utilize natural Hb by modifying it with a chemical reactions. The membrane of a red blood cell (storoma) has type compounds and causes unconformity of the blood groups and so on. On the other hand, the storoma-free Hb is common for normal human bodies. But when the storoma-free Hb is injected in a blood circular, it is cleared up within a few minutes. To avoid this problem, the storoma-free Hb is combined with a synthetic polymer such as dextran the Hb is polymerized with glutaraldehyde the Hb is encapsulated with a synthetic polymer such as nylon and the Hb is encapsulated with the phospholipid liposome instead of the red blood cell membrane But there still remain problems such as supply of ultra-pure human Hb. 

Adsorption on liposome surfaces Dimethyl suberimidate- or glutaraldehyde-mediated coupling to liposome surfaces Enzyme incorporation into liposomes during formation Reaction with cellulose cyclic imidocarbonate... 

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