Efficient skin interactions of graphene derivatives: challenge, opportunity or both?

Interactions between graphene, with its wide deployment in consumer products, and skin, the body's largest organ and first barrier, are highly relevant with respect to toxicology and dermal delivery. In this work, interaction of polyglycerol-functionalized graphene sheets, with 200 nm average lateral size and different surface charges, and human skin was studied and their potential as topical delivery systems were investigated. While neutral graphene sheets showed no significant skin interaction, their positively and negatively charged counterparts interacted with the skin, remaining in the stratum corneum.

Human serum albumin nanotubes with esterase activity.

A nanocylindrical wall structure was obtained by layer-by-layer (LbL) assembly of poly-L-arginine (PLA) and human serum albumin (HSA) and characterized by scanning electron microscopy (SEM), scanning force microscopy (SFM), and cryogenic transmission electron microscopy (cryo-TEM). SEM and SFM measurements of a lyophilized powder of (PLA/HSA)(3) nanotubes yielded images of round, chimney-like architectures with approximately 100 nm wall thickness. Cryo-TEM images of the hydrated sample revealed that the tube walls are composed of densely packed HSA molecules.

Flexible loops of thread-like micelles are formed upon interaction of L-alpha-dimyristoyl-phosphatidylcholine with the biosurfactant surfactin as revealed by cryo-electron tomography.

Vesicles of L-alpha-dimyristoyl-phosphatidylcholine (DMPC) are known to disintegrate upon treatment with surfactin, a lipoheptapeptide biosurfactant from Bacillus subtilis OKB 105, as was observed by static light scattering (SLS) and cryo-transmission electron microscopy (cryo-TEM) recently. The lysis of DMPC bilayers occurs strongly dependent on the surfactin concentration according to a three-stage model. Unilamellar DMPC vesicles are disrupted to form sheet-like lamellar intermediates at a moderate surfactant concentration, but undergo a transition towards smaller particles of unknown structure at a higher surfactant concentration according to earlier neutron scattering experiments.

A novel green template for the synthesis of mesoporous silica.

Mesoporous pure silicas and functionalized silica with a narrow pore size distribution centered at 3.8 nm were prepared by a novel template, amphiphilic dendritic polyglycerol. The resulting silica materials were characterized by electron microscopy; nitrogen adsorption; (1)H, (13)C, and (29)Si solid-state cross-polarization magic-angle spinning NMR spectroscopy.

Physicochemical studies of the interaction of the lipoheptapeptide surfactin with lipid bilayers of L-alpha-dimyristoyl phosphatidylcholine.

To understand the biological action of surfactin from Bacillus subtilis we investigated its effects on the phase transition of L-alpha-dimyristoyl phosphatidylcholine (DMPC)-vesicles from the crystalline to the fluid state using differential scanning calorimetry; light scattering; small angle neutron scattering and cryo-electron microscopy. DSC-thermograms revealed two phase transition peaks. Light scattering profiles showed two branches with characteristic hysteresis phenomena.