Sporopollenin exine capsules (SECs) (outer exoskeletal wall of the spores of Lycopodium clavatum) were extracted and examined for their potential use as microcapsules. They were shown, by laser scanning confocal microscopy (LSCM), to be void of their inner contents. The removal of nitrogenous and other internal materials was supported by a combination of elemental and gravimetric analyses. Two different methods were investigated to encapsulate substances into SECs which were (i) mild passive migration of materials into the SECs and (ii) subjecting SECs and materials to a vacuum. A range of fluorescent dyes with different polarities were seen using LSCM to encapsulate efficiently into the SECs (up to 1 g.g À1 ). Relatively unstable materials with different polarities were encapsulated into the SECs: polyunsaturated oils, which are labile to oxidation, and the enzymes streptavidin-horseradish peroxidase (sHRP) and alkaline phosphatase (ALP). Irrespective of the encapsulation techniques employed no oxidation of the oils or denaturation of the enzymes was observed following their full recovery. This study gives the first indication of the viability of SECs to microencapsulate various potentially unstable materials without causing a detrimental effect.

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The exine coatings of spores can be used to encapsulate drug molecules. We have demonstrated that these microcapsules can be filled with a commercial gadolinium(III) MRI contrast agent (in this proof of concept study Gd-DTPA-BMA was used) which is slowly released in plasma due to enzymatic digestion of the capsule.

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Gene therapy for treating inherited diseases like cystic fibrosis might be achieved using multimodular nonviral lipid-based systems. To date, most optimizations have concerned cationic lipids rather than colipids. In this study, an original archaeal tetraether derivative was used as a colipid in combination with one or the other of two monocationic amphiphiles. The liposomes obtained, termed archaeosomes, were characterized regarding lipid self-assembling properties, macroscopic/microscopic structures, DNA condensation/neutralization/relaxation abilities, and colloidal stability in the presence of serum. In addition, gene transfer experiments were conducted in mice with lipid/DNA complexes being administered via systemic or local delivery routes. Altogether, the results showed that the tetraether colipid can provide complexes with different in vivo transfection abilities depending on the lipid combination, the lipid/colipid molar ratio, and the administration route. This original colipid appears thus as an innovative modular platform endowed with properties possibly beneficial for fine-tuning of in vivo lipofection and other biomedical applications.