Enzyme-Mediated Formation of Vesicles from DPPC−Dodecyl Maltoside Mixed Micelles

Abstract

An enzymatic procedure for liposome formation through micelle to vesicle transition is described. Amyloglucosidase hydrolysis of dodecyl--D-maltoside (DM) giving dodecyl--D-glucoside (DG) leads to dipalmitoylphosphatidylcholine (DPPC)-based vesicle formation from DPPC-DM mixed micelles. Starting from a 1.8 DM/DPPC molar ratio corresponding to mixed micelles, progressive hydrolysis of DM gives DPPC-DG-DM intermediate aggregates ending with DPPC-DG vesicles upon reaction completion. Initial steps of the process corresponding to the exit of the micellar domain were followed by turbidimetry measurements. Next, the reaction progress was investigated by RP-HPLC, HPLC-GEC, and cryofracture electron microscopy. A constant reaction rate is observed in the micellar domain, while the increase of the lamellae proportion considerably decreases the enzyme catalytic activity. Finally, the enzymatic hydrolysis is significally slowed when closed vesicles are formed. Enzymatic activity is dependent on DM availability in the bulk phase and of the DM/DPPC molar ratio in the aggregates. The presence of mixed micelles or lamellar sheets considerably modulates DM monomer concentration in the aqueous phase. The liposomes formed by the enzymatic process are spherical, unilamellar, and heterogeneous in size with a mean diameter ranging from 10 to 80 nm.

Phase Behavior of Mixed Aqueous Dispersions of Dipalmitoylphosphatidylcholine and Dodecyl Glycosides: A Differential Scanning Calorimetry and X-ray Diffraction Investigation

“…Another motivation arises from the fact that these two surfactants were directly implicated in the enzymatic process of DPPC vesicle formation that we developed a few years ago and based on the DM hydrolysis into DG by amyloglucosidase. [24][25][26] This involved the transition from DPPC-DM mixed micelles to DPPC-DG mixed vesicles via distinct aggregation states depending on the intermediate compositions of the ternary DPPC-DM-DG reaction mixture. 25,26 Starting from an isotropic micellar solution, the following structures successively appeared: (1) mixed micelles separating from the aqueous phase, (2) coexisting lamellar and micelle-like assemblies, (3) open bilayer fragments or disks, and (4) closed vesicles.…”

“…[24][25][26] This involved the transition from DPPC-DM mixed micelles to DPPC-DG mixed vesicles via distinct aggregation states depending on the intermediate compositions of the ternary DPPC-DM-DG reaction mixture. 25,26 Starting from an isotropic micellar solution, the following structures successively appeared: (1) mixed micelles separating from the aqueous phase, (2) coexisting lamellar and micelle-like assemblies, (3) open bilayer fragments or disks, and (4) closed vesicles. Moreover, the sequence of these structural domains was shown to be sensitive to temperature variations, bilayer formation being favored by heating.…”

Endowing catanionic surfactant vesicles with dual responsive abilities via a noncovalent strategy: introduction of a responser, sodium cholate

“…[8][9][10] Indeed, responsive vesicles are superior to conventional vesicles and show great potential in drug/gene delivery or protein reconstitutions. [11][12][13] So far, they have been achieved by functionalizing amphiphiles in which responsive moieties, such as amines, ferrocene, azobenzenes, and amylases, are covalently incorporated. [12][13][14][15][16][17][18][19][20] However, most of the functionalized molecules require laborious, multi-step, or even low-yield syntheses, and their resultant vesicles only respond to one stimulus.…”

“…[11][12][13] So far, they have been achieved by functionalizing amphiphiles in which responsive moieties, such as amines, ferrocene, azobenzenes, and amylases, are covalently incorporated. [12][13][14][15][16][17][18][19][20] However, most of the functionalized molecules require laborious, multi-step, or even low-yield syntheses, and their resultant vesicles only respond to one stimulus. To sidestep these difficult syntheses and endow vesicles with multi-responsive abilities, an alternative noncovalent strategy is proposed in this paper.…”

A New Approach to the Stereospecific Synthesis of Phospholipids. The Use of l-Glyceric Acid for the Preparation of Diacylglycerols, Phosphatidylcholines, and Related Derivatives

“…Significantly, some of the most potent phospholipid compounds, which are active below the micromolar 8 and nanomolar 3 levels, occur in low concentrations in the cell, such that preparation of synthetic derivatives represents a clear prerequisite to elucidation of their biochemical mechanism of action. The compounds are required for both structural and dynamic studies of biomembranes − and membrane-bound enzymes, ,,, with particular emphasis on establishing structure−activity relationships with respect to phospholipid−phospholipid 13-16 and phospholipid−protein 17 interactions. Furthermore, delineation of the structural requirements for the biological activities of phospholipids will not only advance the current level of understanding of the chemistry and biology of these compounds but also provide important insight into the design of new target molecules with the desired activity and potency.…”