Gel-assisted formation of giant unilamellar vesicles

Giant unilamellar vesicles or GUVs are systems of choice as biomimetic models of cellular membranes. Although a variety of procedures exist for making single walled vesicles of tens of microns in size, the range of lipid compositions that can be used to grow GUVs by the conventional methods is quite limited, and many of the available methods involve energy input that can damage the lipids or other molecules present in the growing solution for embedment in the membrane or in the vesicle interior. Here, we show that a wide variety of lipids or lipid mixtures can grow into GUVs by swelling lipid precursor films on top of a dried polyvinyl alcohol gel surface in a swelling buffer that can contain diverse biorelevant molecules. Moreover, we show that the encapsulation potential of this method can be enhanced by combining polyvinyl alcohol-mediated growth with inverse-phase methods, which allow (bio)molecule complexation with the lipids

Interaction of cyclic and linear labaditin peptides with anionic and zwitterionic micelles

Conformational changes of the cyclic (Lo) peptide Labaditin (VWTVWGTIAG) and its linear analogue (L1) promoted by presence of anionic sodium dodecyl sulfate (SDS) and zwitterionic L-α-Lysophosphatidylcholine (LPC) micelles were investigated. Results from λmax blue-shift of tryptophan fluorescence emission combined with Stern–Volmer constants values and molecular dynamics (MD) simulations indicated that L1 interacts with SDS micelles to a higher extent than does Lo. Further, the MD simulation demonstrated that both Lo and L1 interact similarly with LPC micelles, being preferentially located at the micelle/water interface. The peptide–micelle interaction elicits conformational changes in the peptides. Lo undergoes limited modifications and presents unordered structure in both LPC and SDS micelles. On the other hand, L1 displays a random-coil structure in aqueous medium, pH 7.0, and it acquires a β-structure upon interaction with SDS and LPC, albeit with structural differences in each medium.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq