Electrically conductive flexible carbon papers were prepared, based on hydroxyl functionalized few layer graphene (G-OH). G-OH was obtained from the reaction of KOH with nanosized graphite with a very high surface area (HSAG), greater than 300 m2 g-1, and with high shape anisotropy, with the help of mechanical and thermal energy. Wide angle X-ray and Raman analyses showed that the core of G-OH had the structure of infinite and ideal graphene layers and that the interlayer distance between the few stacked graphene layers was the same as in pristine HSAG. Hydroxyl groups were thus essentially located in peripheral positions. High resolution transmission electron microscopy revealed the presence of graphene aggregates made by a number of layers as low as 6. Stable water suspensions were obtained, with concentrations up to 4 mg mL-1. Mild centrifugation of such suspensions had interesting efficiency as a method for producing few layer graphene: about 35% by mass of pristine HSAG was isolated as few layer graphene from supernatant suspensions. Flexible and electrically conductive carbon papers were prepared by coating a paper support with a G-OH water suspension. This work demonstrates that carbon papers can be prepared without adopting the traditional oxidation-reduction procedure, avoiding harsh reaction conditions, dangerous and toxic reagents, solvents and catalysts
An emitting nanoassembly composed of a novel amphiphilic cyclodextrin functionalised with a covalently appended fluorophore and an anionic porphyrin internalizes effectively in tumor cells, allowing simultaneously the detection of carrier and photosensitiser.
Light scattering and time-resolved fluorescence spectroscopy results showed that specially
designed amphiphilic cyclodextrins are able to bind a specific protein, PA-I lectin. When
containing a galactosyl group, the self-assembled cyclodextrins interact with the protein
affecting the dynamical properties of the system and the fluorescence lifetimes (as well as
the fluorescence anisotropy) of the protein itself. The self-assembled cyclodextrins
containing a glucosyl group, on the other hand, do not induce any change in
these measured quantities, suggesting no interaction with protein. This binding
capability of galactosyl-modified cyclodextrins offers perspectives on exploiting
self-assembled supramolecular structures as nano-carriers to deliver drugs to target tissues.
Heparin has been conjugated to Fe3O4, Co3O4, and NiO nanoparticles (NPs) through electrostatic interactions, producing colloidal suspensions of hybrid metal oxide heparin NPs that are stable in water. Negative zeta potentials and retention of heparin’s ability to capture toluidine blue indicate that heparin’s negative charges are exposed on the surface of the coated NPs. IR results confirmed the formation of nanohybrids as did NMR experiments, which were also interpreted on the basis of toluidine blue tests. Transmission electron microscopy results revealed that the heparin coating does not modify the shape or dimension of the NPs. Dynamic light scattering and negative zeta potential measurements confirmed that heparin surface functionalisation is an effective strategy to prevent NP aggregation.
High-grade cellulose (97% α-cellulose content) of 48% crystallinity index was extracted from the renewable marine biomass waste Posidonia oceanica using H2O2 and organic peracids following an environmentally friendly and chlorine-free process. This cellulose appeared as a new high-grade cellulose of waste origin quite similar to the high-grade cellulose extracted from more noble starting materials like wood and cotton linters. The benefits of α-cellulose recovery from P. oceanica were enhanced by its transformation into cellulose acetate CA and cellulose derivative GMA-C. Fully acetylated CA was prepared by conventional acetylation method and easily transformed into a transparent film. GMA-C with a molar substitution (MS) of 0.72 was produced by quenching Fenton’s reagent (H2O2/FeSO4) generated cellulose radicals with GMA. GMA grafting endowed high-grade cellulose from Posidonia with adsorption capability. GMA-C removes β-naphthol from water with an efficiency of 47%, as measured by UV-Vis spectroscopy. After hydrolysis of the glycidyl group to glycerol group, the modified GMA-C was able to remove p-nitrophenol from water with an efficiency of 92%, as measured by UV-Vis spectroscopy. α-cellulose and GMA-Cs from Posidonia waste can be considered as new materials of potential industrial and environmental interest.
High-yield regioselective synthesis of imines and oxazolidines derivatives of 2-amino-1,3-propandiol (serinol) was achieved by performing the reaction with aldehydes and ketones, in the absence of solvents and catalysts. Only imines were obtained when the carbonyl compound was aromatic and/or sterically hindered and when conjugated double bonds were formed. 1,3-Oxazolidines were specifically obtained with either aldehydes or ketones with limited steric hindrance. The "green" reaction conditions here adopted for the synthesis of these classes of derivatives are not due to the structural and functional peculiarity of the serinol as a reactant and can also be extended to lipophilic amines with the same good results in terms of yield and selectivity. A revision of the mechanism typically accepted in the presence of solvent and catalysis is proposed, and the quantum mechanics calculations applied to some derivatives are in good agreement with the proposed rationalizations of the selectivity observed. Serinol itself and the imine and oxazolidine derivatives were used, in place of guanidine, as accelerators in compounds based on diene rubbers and silica, suitable for application in tire treads with low environmental impact. Efficient sulfur-based cross-linking and composites with a low dissipation of energy were obtained. The oxazolidine and imine appear to act as protective groups of the serinol primary amine. This work paves the way for the selective synthesis of biosourced families of chemicals, which could be used for large-scale applications, such as the one in rubber compounds, replacing toxic oil-based chemicals.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.