Preparation and Properties of Semi-Self-Assembled Lipopeptide Vesicles.

Novel lipopeptide vesicles are prepared from self-assembled nanomembranes through an extrusion method. The size of vesicles can be controlled by the pore diameter of the extrusion filter. The vesicles are rather stable because hydrogen bonds exist among the peptide headgroups. When doxorubicin hydrochloride (DOX·HCl) is encapsulated in the vesicles, it could be released sustainably, and its side effect would also be reduced due to encapsulation. The leakage rate of DOX·HCl depends on the pH via charge regulation. As drug carriers, lipopeptide vesicles have been proved to have nontoxicity to normal cells. A magnetic surfactant CH3(CH2)14CH2N(CH3)3+ [FeCl3Br]- (CTAFe) was mixed with lipopeptide to modify the vesicles. Also, the results demonstrated that the vesicles is endowed with magnetic property after the addition of CTAFe. We believe that the strategy of lipopeptide vesicle preparation would enrich the drug carrier family and expand the application of lipopeptide materials.

Light- and pH-Controlled Hierarchical Coassembly of Peptide Amphiphiles.

The coassembly behavior of peptide amphiphiles (PAs) C4-Bhc-EE-NH2 and C14-FKK-NH2 has been investigated by transmission electron microscopy, atomic force microscopy, fluorescence microscopy, circular dichroism, Fourier transform infrared spectroscopy, and 1H nuclear magnetic resonance. These two PAs coassembled into nanofibers by electrostatic and π-π stacking interactions at a low concentration and further aggregated into nanofiber bundles via charge complementation on the surface of nanofibers. As the charge number varied with pH, the bundles could be disassembled/assembled with pH regulation. More interestingly, as C4-Bhc-EE-NH2 was a photodegradable molecule, the bundles could also be responsive to both ultraviolet (UV) and near-infrared (NIR) light. In contrast to the reversible pH-dependent response, the light responses were irreversible as C4-Bhc-EE-NH2 broke under UV or NIR radiation. The highlight of this article is that structural changes were realized for control at the aggregate level, not only at the molecular level. With this inspiration, we hope that we can support the novel biomaterial construction and exploitation of new functions of biomaterials.

Preparation and characterization of ß-casein stabilized lipopeptide lyotropic liquid crystal nanoparticles for delivery of doxorubicin.

A kind of lyotropic liquid crystal nanoparticle (LLC NPs) has been designed and prepared. LLC NPs are dSMO/OA/ß-casein/water quaternary systems, and their cubic or hexagonal microstructures have been characterized by cryogenic transmission electron microscopy (cryo-TEM) and small angle X-ray scattering (SAXS). The phase transition of LLC NPs takes place with ratio and pH adjustments. The properties, such as cytotoxicity, stability, drug encapsulation and release ability, have been investigated with MTT assay, cryo-TEM and UV-Vis spectroscopy. The results showed that LLC NPs were nontoxic to cells and stable to enzymatic degradation. Hydrophilic drug doxorubicin hydrochloride (DOX·HCl) could be effectively encapsulated in LLC NPs and its release rate could be regulated by pH. It was concluded that LLC NPs are potential nanocarriers in nanomedicine technologies. We hope that this work provides new guidelines for the rational design of LLC NP systems with lipopeptides for biomedical applications.

UV and NIR dual-responsive self-assembly systems based on a novel coumarin derivative surfactant.

Controllable self-assembly systems have attracted increasing attention in both the academic and industrial fields recently. Herein, we designed and synthesized a new photo-degradable anionic surfactant (PAS) with a coumarin group which could be degraded by both UV and NIR light. Thus, the micelles that are formed by sodium salts of PAS (PAS-Na) could be broken controllably under UV or NIR irradiation. Surface tension measurements, DLS, and Cryo-TEM were adopted to investigate the formation and disruption of PAS-Na micelles. PAS could also form wormlike micelles and vesicles when they co-assembled with common surfactant tetradecyldimethylamine oxide (C14DMAO). These wormlike micelles and vesicles could be degraded by UV and NIR irradiation due to the participation of PAS. Accordingly, the rheology properties of the wormlike micelles and vesicles were also changed significantly. Finally, the stimulus-responsive system was used to control the diffusion of hydrophobic and hydrophilic molecules. And it has shown controllable release effects on both the hydrophobic and hydrophilic molecules.