Superstructures of lipids and graphene

This thesis systematically analyzes the physical-chemistry of lipid-graphene interactions with the major objective of reconciliating the variety of results reported in the literature. By using five major characterization techniques typically used to study lipids, namely IR spectroscopy, ellipsometry, AFM, neutron reflectivity and QCM-D, this thesis characterizes – in details – layered structures of graphene and lipids (so called superstructures) and separately studies the dynamics of the interaction between lipids and graphene. The most remarkable result is that through the systematic construction of i) a lipid monolayer on a silicon substrate; ii) the subsequent coating with graphene and iii) the deposition of a last lipid monolayer on top of the two layers stack; graphene could be encapsulated in the hydrophobic core of a lipid bilayer for the first time, promising a range of applications to sense biological processes occurring near or inside a lipid bilayer. Supramolecular & Biomaterials Chemistr

Graphene-stablized lipid monolayer heterostructures: a novel biomembrane superstructure

Supramolecular & Biomaterials Chemistr

Contact angle measurement of free-standing square-millimeter single-layer graphene

Supramolecular & Biomaterials Chemistr

Sensing at the surface of graphene field-effect transistors

Supramolecular & Biomaterials Chemistr

Sensing at the Surface of Graphene Field-Effect Transistors

Recent research trends now offer new opportunities for developing the next generations of label‐free biochemical sensors using graphene and other two‐dimensional materials. While the physics of graphene transistors operated in electrolyte is well grounded, important chemical challenges still remain to be addressed, namely the impact of the chemical functionalizations of graphene on the key electrical parameters and the sensing performances. In fact, graphene – at least ideal graphene – is highly chemically inert. The functionalizations and chemical alterations of the graphene surface – both covalently and non‐covalently – are crucial steps that define the sensitivity of graphene. The presence, reactivity, adsorption of gas and ions, proteins, DNA, cells and tissues on graphene have been successfully monitored with graphene. This review aims to unify most of the work done so far on biochemical sensing at the surface of a (chemically functionalized) graphene field‐effect transistor and the challenges that lie ahead. The authors are convinced that graphene biochemical sensors hold great promise to meet the ever‐increasing demand for sensitivity, especially looking at the recent progresses suggesting that the obstacle of Debye screening can be overcome.Supramolecular & Biomaterials Chemistr

Third-generation cholecystectomy by natural orifices: transgastric and transvesical combined approach (with video)

An isolated transgastric port has some limitations in performing transluminal endoscopic cholecystectomy. However, transvesical access to the peritoneal cavity has recently been reported to be feasible and safe. Background An isolated transgastric port has some limitations in performing transluminal endoscopic cholecystectomy. However, transvesical access to the peritoneal cavity has recently been reported to be feasible and safe. Objective To assess the feasibility and the technical benefits of transgastric and transvesical combined approach to overcome the limitations of isolated transgastric ports. Design We created a transgastric and transvesical combined approach to perform cholecystectomy in 7 consecutive anesthetized female pigs. The transgastric access was achieved after perforation and dilation of the gastric wall with a needle knife and with a balloon, respectively. Under cystoscopic control, an ureteral catheter, a guidewire, and a dilator of the ureteral sheath were used to place a transvesical 5-mm overtube into the peritoneal cavity. By using a gastroscope positioned transgastrically and a ureteroscope positioned transvesically, we carried out cholecystectomy in all animals. Results Establishment of transvesical and transgastric accesses took place without complications. Under a carbon dioxide pneumoperitoneum controlled by the transvesical port, gallbladder identification, cystic duct, and artery exposure were easily achieved in all cases. Transvesical gallbladder grasping and manipulation proved to be particularly valuable to enhance gastroscope-guided dissection. With the exclusion of 2 cases where mild liver-surface hemorrhage and bile leak secondary to the sliding of cystic clips occurred, all remaining cholecystectomies were carried out without incidents. Limitations Once closure of the gastric hole proved to be unreliable when using endoclips, the animals were euthanized; necropsy was performed immediately after the surgical procedure. Conclusions A transgastric and transvesical combined approach is feasible, and it was particularly useful to perform a cholecystectomy through exclusive natural orifices

Lectins: production and practical applications

Lectins are proteins found in a diversity of organisms. They possess the ability to agglutinate erythrocytes with known carbohydrate specificity since they have at least one non-catalytic domain that binds reversibly to specific monosaccharides or oligosaccharides. This articles aims to review the production and practical applications of lectins. Lectins are isolated from their natural sources by chromatographic procedures or produced by recombinant DNA technology. The yields of animal lectins are usually low compared with the yields of plant lectins such as legume lectins. Lectins manifest a diversity of activities including antitumor, immunomodulatory, antifungal, HIV-1 reverse transcriptase inhibitory, and anti-insect activities, which may find practical applications. A small number of lectins demonstrate antibacterial and anti-nematode activities