On Biomimetics
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Fig. 4. Structure of folic acid conjugated to a diether-type archaeal lipid.
Albeit this methodology needs further improvement, the design of new vectors based on the
cholesterol and archeal lipids is expected to provide new opportunities to overcome the
critical limitations of current gene delivery systems, such as low efficiency of transfection in
vivo, potential toxicity and acute immune response.
- Biomimetic cell membranes
Terpenoids are universal membrane constituents and are essential to reinforce the
membranes of all living organisms (Rohmer et al., 1979). Long term investigation of Guy
Ourisson and Yoichi Nakatani on polyprenoids in the fossil record and membrane
reinforcers has prompted them to propose a phylogenetic classification of membrane
terpenoids (Fig. 5) (Ourisson & Nakatani, 1994).
Fig. 5. Hypothetical evolution of membrane polyprenoids (modified from Ourisson &
Nakatani, 1994).
From a retrograde analysis, they have proposed that polyprenyl phosphates might be even
more primitive membrane constituents than archeal membrane lipids. And they have
postulated that primitive membranes could have been more readily formed from the