Aihua Zou

Baicalin loaded in folate-PEG modified liposomes for enhanced stability and tumor targeting

Bioavailability of baicalin (BAI), an example of traditional Chinese medicine, has been modified by loading into liposome. Several liposome systems of different composition i.e., lipid/cholesterol (L), long-circulating stealth liposome (L-PEG) and folate receptor (FR)-targeted liposome (L-FA) have been used as the drug carrier for BAI. The obtained liposomes were around 80 nm in diameter with proper zeta potentials about -25 mV and sufficient physical stability in 3 months. The entrapment efficiency and loading efficiency of BAI in the liposomes were 41.0-46.4% and 8.8-10.0%, respectively. The morphology details of BAI lipsosome systems i.e., formation of small unilamellar vesicles, have been determined by cryogenic transmission electron microscopy (cryo-TEM) and small angle X-ray scattering (SAXS). In vitro cytotoxicity of BAI liposomes against HeLa cells was evaluated by MTT assay. BAI loaded FR-targeted liposomes showed higher cytotoxicity and cellular uptake compared with non-targeted liposomes. The results suggested that L-FA-BAI could enhance anti-tumor efficiency and should be an effective FR-targeted carrier system for BAI delivery.

Sterically stabilized spongosomes for multidrug delivery of anticancer nanomedicines

Multidrug delivery devices are designed to take advantage of the synergistic effects of anticancer agents in combination therapies. Here we report novel liquid crystalline self-assembled nanocarriers enhancing the activity of the phytochemical anticancer agent baicalin (BAI) in combination with Brucea javanica oil (BJO), which ensures safe formulations for clinical applications. Small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) evidenced the multicompartment, sponge-type nano-organization of the blank and multidrug-loaded liquid crystalline carriers. Physico-chemical stability of the sponge nanoparticles was achieved through PEGylation of the lipid membranes, which make up the drug nanocarriers. The proposed green nanotechnology for nanocarrier preparation by supramolecular self-assembly provided a multidrug encapsulation efficiency as high as 75%. The apoptosis study with the human lung carcinoma cell line A549 demonstrated improved efficacy of the multidrug delivery nanocarriers in comparison to the single-drug reservoirs. The obtained results evidenced the synergistic anticancer apoptotic effects of the multidrug-loaded nanosponge carriers and suggested the opportunity for in vivo translation towards the treatment of lung, gastrointestinal, and ovarian cancers.

Counterion-Induced Changes to the Micellization of Surfactin-C16 Aqueous Solution

The effects of counterions on surfactin-C(16) micelle solution with its critical micelle concentration (cmc), microenvironment properties in micelles, micelle size distribution, and morphology were investigated by fluorescence, dynamic light-scattering, and freeze-fracture transmission electron microscopy measurements. Counterions enhanced the surface activity of surfactin-C(16) and reduced the cmc. With the micellization of surfactin-C(16), it adopted a beta-sheet conformation, and univalent concentrations reduced micelle micropolarity, increased micelle microviscosity, and tended to cause formation of small and spherical micelles, while divalent counterions had a special effect. With low concentration of divalent cations, they had strong interaction with surfactin-C(16) micelles and tended to form larger micelle aggregates.

Toluidine blue: Aggregation properties and distribution behavior in surfactin micelle solution

Aggregation properties and distribution behavior of toluidine blue in surfactin solution have been investigated by UV, infrared spectrum and fluorescence measurements. The UV measurement indicates that the location of toluidine blue can facilitate the formation of toluidine blue aggregates in contrast to that in the absence of surfactin. The fluorescence results show that the micropolarity of pyrene initially increases and then decreases with the addition of toluidine blue molecules. The binding constants of toluidine blue with surfactin micelles and the distribution coefficients between the micelles phase and the aqueous phase have been calculated by Benesi-Hildebrand method and pseudo-phase model, respectively. The values of DeltaH degrees < 0 (-22.11 kJ/mol) and DeltaS degrees > 0 (12.58+/-0.07 J/(mol K)) show that electrostatic attractive interaction plays an important role in the location of toluidine blue in surfactin micelles.

Preparation and characterization of 4-dedimethylamino sancycline (CMT-3) loaded nanostructured lipid carrier (CMT-3/NLC) formulations

Chemically modified tetracyclines (CMTs) have been reported to strongly inhibit proliferation and metastasis of various cancers, but their efficacy is restricted by poor water solubility. In the present study, a hydrophilic 4-dedimethylamino sancycline (CMT-3) loaded nanostructured lipid carrier (CMT-3/NLC) was produced by high pressure homogenization (HPH). The physical properties of CMT-3/NLC formulations were characterized by dynamic light scattering (DLS), high efficiency liquid chromatography (HPLC), atomic force microscopy (AFM), scanning electron microscopy (SEM), small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS) and wide-angle X-ray powder diffraction (XRD). The lipid and surfactant ingredients, as well as drug/lipid concentrations (m/m) were optimized to produce stable and sustained NLC formulations. In vitro cytotoxicity of CMT-3/NLC against HeLa cells was evaluated by MTT assay. The diameter of CMT-3/NLC was found to increase from 153.1±3.0 nm to a maximum of 168.5±2.0 nm after 30 days of storage, while the entrapment efficiency remained constant at >90%. CMT-3/NLC demonstrated a burst-sustained release profile in release media with different pH, a property attributed to the 3-dimensional structure of CMT-3/NLC. Cell uptake and localization studies indicated that NLC reached the cytoplasm and could thereby facilitate CMT-3 entry into HeLa cells.

Advances in structural design of lipid-based nanoparticle carriers for delivery of macromolecular drugs, phytochemicals and anti-tumor agents

The present work highlights recent achievements in development of nanostructured dispersions and biocolloids for drug delivery applications. We emphasize the key role of biological small-angle X-ray scattering (BioSAXS) investigations for the nanomedicine design. A focus is given on controlled encapsulation of small molecular weight phytochemical drugs in lipid-based nanocarriers as well as on encapsulation of macromolecular siRNA, plasmid DNA, peptide and protein pharmaceuticals in nanostructured nanoparticles that may provide efficient intracellular delivery and triggered drug release. Selected examples of utilisation of the BioSAXS method for characterization of various types of liquid crystalline nanoorganizations (liposome, spongosome, cubosome, hexosome, and nanostructured lipid carriers) are discussed in view of the successful encapsulation and protection of phytochemicals and therapeutic biomolecules in the hydrophobic or the hydrophilic compartments of the nanocarriers. We conclude that the structural design of the nanoparticulate carriers is of crucial importance for the therapeutic outcome and the triggered drug release from biocolloids.

Mixture of Nonionic/Ionic Surfactants for the Formulation of Nanostructured Lipid Carriers: Effects on Physical Properties

The objective of the present work was to investigate the effects of the mixture of nonionic/ionic surfactants on nanostructured lipid carriers (NLCs). Nonionic surfactant (polyethylene-poly(propylene glycol), Pluronic F68) and ionic surfactant (octenylsuccinic acid modified gum arabic, GA-OSA) were chosen as emulsifier for NLCs. The NLCs systems, which were composed of lipid matrix, modified 4-dedimethylaminosancycline (CMT-8), and various emulsifier agents, were characterized with dynamic light scattering (DLS), high performance liquid chromatography (HPLC), transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), in vitro release, and phagocytosis assay. This mixture of nonionic/ionic surfactants showed significant effects on physical properties including particle size, polydispersity index (PDI), entrapment efficiency, and particle morphology. Compared with single stabilizer, this mixed nonionic/ionic surfactant system provided NLCs with better drug carrier properties including prolonged release profile and low phagocytosis by phagocyte. We expect that these explorations can provide a new strategy for the development of lipid nanoparticles as drug delivery.

Micellization activity of the natural lipopeptide [Glu1, Asp5] surfactin-C15 in aqueous solution.

Surface tension, small angle neutron scattering (SANS), freeze-fracture transmission electron microscopy (FF-TEM), and circular dichroism (CD) have been used to study the self-aggregation properties of the natural lipopeptide [Glu(1), Asp(5)] surfactin-C15 in 0.01 M phosphate buffer solution (PBS) at pH 7.4. It has been found that the critical micelle concentration (cmc) of surfactin is 1.54 x 10(-5) M, the surface tension at the cmc (sigma(cmc)) is 27.7 mN/m, and the area per molecule at the air-water interface is 107.8 A(2). Surfactin molecules adopt a beta-sheet conformation already at low concentrations. This feature probably makes it surface-active at such low concentrations. From SANS and FF-TEM results, it is seen that surfactin exhibits a strong self-assembly ability to form sphere-like micelles and some larger aggregates even at the rare low concentration. The aggregation number of sphere-like micelles is much smaller than that for conventional surfactants of similar alkyl chain length.

Insights into the Interactions among Surfactin, Betaines, and PAM: Surface Tension, Small-Angle Neutron Scattering, and Small-Angle X-ray Scattering Study

The interactions among neutral polymer polyacrylamide (PAM) and the biosurfactant Surfactin and four betaines, N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SDDAB), N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (STDAB), N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (SHDAB), and N-dodecyl-N,N-dimethyl-2-ammonio-acetate (C12BE), in phosphate buffer solution (PBS) have been studied by surface tension measurements, small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and rheological experiments. It has been confirmed that the length of alkyl chain is a key parameter of interaction between betaines and PAM. Differences in scattering contrast between X-ray and neutrons for surfactants and PAM molecules provide the opportunity to separately follow the changes of structure of PAM and surfactant aggregates. At concentrations of betaines higher than CMC (critical micelle concentration) and C2 (CMC of surfactant with the presence of polymer), spherical micelles are formed in betaines and betaines/PAM solutions. Transition from spherical to rod-like aggregates (micelles) has been observed in solutions of Surfactin and Surfactin/SDDAB (αSurfactin = 0.67 (molar fraction)) with addition of 0.8 wt % of PAM. The conformation change of PAM molecules only can be observed for Surfactin/SDDAB/PAM system. Viscosity values follow the structural changes suggested from scattering measurements i.e., gradually increases for mixtures PAM → Surfactin/PAM → Surfactin/SDDAB/PAM in PBS.

Self-assembled stable sponge-type nanocarries for Brucea javanica oil delivery

Sponge-type nanocarriers (spongosomes) are produced upon dispersion of a liquid crystalline sponge phase formed by self-assembly of an amphiphilic lipid in excess aqueous phase. The inner organization of the spongosomes is built-up by randomly ordered bicontinuous lipid membranes and their surfaces are stabilized by alginate chains providing stealth properties and colloidal stability. The present study elaborates spongosomes for improved encapsulation of Brucea javanica oil (BJO), a traditional Chinese medicine that may strongly inhibit proliferation and metastasis of various cancers. The inner structural organization and the morphology characteristics of BJO-loaded nanocarriers at varying quantities of BJO were determined by cryogenic transmission electron microscopy (Cryo-TEM), small angle X-ray scattering (SAXS) and dynamic light scattering (DLS). Additionally, the drug loading and drug release profiles for BJO-loaded spongosome systems also were determined. We found that the sponge-type liquid crystalline lipid membrane organization provides encapsulation efficiency rate of BJO as high as 90%. In vitro cytotoxicity and apoptosis study of BJO spongosome nanoparticles with A549 cells demonstrated enhanced anti-tumor efficiency. These results suggest potential clinical applications of the obtained safe spongosome formulations.