Exploring Potential Impact of Graphene Oxide and Graphene Oxide-Polyethylenimine on Biological Behavior of Human Amniotic Fluid-Derived Stem Cells.

Regenerative medicine and tissue engineering aim to restore or replace impaired organs and tissues using cell transplantation supported by scaffolds. Recently scientists are focusing on developing new biomaterials that optimize cellular attachment, migration, proliferation, and differentiation. Nanoparticles, such as graphene oxide (GO), have emerged as versatile materials due to their high surface-to-volume ratio and unique chemical properties, such as electrical conductivity and flexibility.

Fine-tuning of membrane permeability by reversible photoisomerization of aryl-azo derivatives of thymol embedded in lipid nanoparticles.

Responsiveness of liposomes to external stimuli, such as light, should allow a precise spatial and temporal control of release of therapeutic agents or ion transmembrane transport. Here, some aryl-azo derivatives of thymol are synthesized and embedded into liposomes from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine to obtain light-sensitive membranes whose photo-responsiveness, release behaviour, and permeability towards Cl ions are investigated. The hybrid systems are in-depth characterized by dynamic light scattering, atomic force microscopy and Raman spectroscopy.

3D Graphene Oxide-Polyethylenimine Scaffolds for Cardiac Tissue Engineering.

The development of novel three-dimensional (3D) nanomaterials combining high biocompatibility, precise mechanical characteristics, electrical conductivity, and controlled pore size to enable cell and nutrient permeation is highly sought after for cardiac tissue engineering applications including repair of damaged heart tissues following myocardial infarction and heart failure. Such unique characteristics can collectively be found in hybrid, highly porous tridimensional scaffolds based on chemically functionalized graphene oxide (GO). By exploiting the rich reactivity of the GO's basal epoxydic and edge carboxylate moieties when interacting, respectively, with NH and NH groups of linear polyethylenimines (PEIs), 3D architectures with variable thickness and porosity can be manufactured, making use of the layer-by-layer technique through the subsequent dipping in GO and PEI aqueous solutions, thereby attaining enhanced compositional and structural control.

Exploring the Assembly of Resorc[4]arenes for the Construction of Supramolecular Nano-Aggregates.

Many biologically active compounds feature low solubility in aqueous media and, thus, poor bioavailability. The formation of the host-guest complex by using calixarene-based macrocycles (i.e.

On-column quantification of amino functionalities bonded to solid porous matrices packed within high performance liquid chromatography columns.

Stationary phases (SPs) based on silica matrices functionalized with amino groups linked to their surface through alkyl chains of various length have found remarkable success in performing HILIC separations, showing really effective resolution towards a wide typology of compounds of biological interest, such as carbohydrates, nucleosides, purine and pyrimidine bases. Recently, we developed an operationally simple procedure, named DNBA-M, non-destructive for the analysed SP, designed to quantify the density of basic groups (typically amino groups) chemically bonded to the surface of porous solids. In the present study the DNBA-M procedure has been suitably modified to allow the quantification of any typology of amino groups present on silica matrices packed into HPLC columns.

Calixarene-based artificial ionophores for chloride transport across natural liposomal bilayer: Synthesis, structure-function relationships, and computational study.

An amphiphilic calix[6]arene, alone or complexed with an axle to form a pseudo-rotaxane, has been embedded into liposomes prepared from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and the permeability of the membrane-doped liposomes towards Cl ions has been evaluated by using lucigenin as the fluorescent probe. The pseudo-rotaxane promotes transmembrane transport of Cl ions more than calix[6]arene does. Surprisingly, the quenching of lucigenin was very fast for liposomes doped with the positively charged axle alone.

Modular and conservative procedure for the quantification of amino functionalities bonded to solid porous matrices.

Nowadays solid materials in which amino groups are linked to silica matrices through alkyl chains of different length (C18, C8, C4) are successfully employed in CO capture and storage technologies, as well as in a variety of chromatographic applications. In particular, their use as stationary phases finds remarkable success in performing HILIC separations and, in general, in the effective resolution of important compound classes (e.g.

Embedding calix[4]resorcinarenes in liposomes: Experimental and computational investigation of the effect of resorcinarene inclusion on liposome properties and stability.

Two calix[4]resorcinarenes, which differ in the length of the alkyl chain on the methylene bridge between the aromatic rings, have been embedded in unilamellar liposomes prepared from 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine in three host/guest ratios, following two different procedures. The effect of the insertion of the guests has been evaluated through the measurements of the viscosity and the kinetic stability of the liposomal systems by means of the fluorescent probes pyrene and 5(6)-carboxyfluorescein. The presence of the guests reduces the viscosity of the liposomes, suggesting a modification of the bilayer structure.

Covalent Decoration of Cortical Membranes with Graphene Oxide as a Substrate for Dental Pulp Stem Cells.

(1) Background: The aim of this study was to optimize, through a cheap and facile protocol, the covalent functionalization of graphene oxide (GO)-decorated cortical membrane (Lamina) in order to promote the adhesion, the growth and the osteogenic differentiation of DPSCs (Dental Pulp Stem Cells); (2) Methods: GO-coated Laminas were fully characterized by Scannsion Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) analyses. In vitro analyses of viability, membrane integrity and calcium phosphate deposition were performed; (3) Results: The GO-decorated Laminas demonstrated an increase in the roughness of Laminas, a reduction in toxicity and did not affect membrane integrity of DPSCs; and (4) Conclusions: The GO covalent functionalization of Laminas was effective and relatively easy to obtain. The homogeneous GO coating obtained favored the proliferation rate of DPSCs and the deposition of calcium phosphate.

Effect of the Incorporation of Functionalized Cyclodextrins in the Liposomal Bilayer.

Liposomes loaded with drug–cyclodextrin complexes are widely used as drug delivery systems, especially for species with low aqueous solubility and stability. Investigation of the intimate interactions of macrocycles with liposomes are essential for formulation of efficient and stable drug-in-cyclodextrin-in-liposome carriers. In this work, we reported the preparation of unilamellar vesicles of 1-palmitoyl-2-oleoyl--glycero-3-phosphocholine (POPC) embedded with native β-cyclodextrin and two synthetic derivatives: heptakis(2,3,6-tri--methyl)-β-cyclodextrin (TMCD) and heptakis(2,3-di--acetyl)-β-cyclodextrin (DACD).

Dispersive magnetic solid phase extraction exploiting magnetic graphene nanocomposite coupled with UHPLC-PDA for simultaneous determination of NSAIDs in human plasma and urine.

A novel, rapid, simple graphene/FeO based dispersive magnetic solid phase extraction was developed for the simultaneous separation/preconcentration and determination of non steroidal anti-inflammatory drugs with ultra high performance liquid chromatography coupled with photodiode array detection. Several parameters influencing the extraction efficiency of the investigated analytes such as the extraction time, the amount of graphene/FeO, the sample pH, the ionic strength and the elution solvent were evaluated and optimized. Under optimal conditions, the linearity was in the range of 0.

Antimicrobial and Antibiofilm Efficacy of Graphene Oxide against Chronic Wound Microorganisms.

Chronic wounds represent an increasing problem worldwide. Graphene oxide (GO) has been reported to exhibit strong antibacterial activity toward both Gram-positive and Gram-negative bacteria. The aim of this work was to investigate the antimicrobial and antibiofilm efficacy of GO against wound pathogens.

Ionic Liquids as "Masking" Solvents of the Relative Strength of Bases in Proton Transfer Reactions.

Equilibrium constants for the proton transfer reaction between pyridines and trifluoroacetic acid were measured in room-temperature ionic liquids (ILs) of different cation-anion compositions. The experimental equilibrium constants for ion-pair formation were corrected according to the Fuoss equation. The calculated equilibrium constants for the formation of free ions were taken as a quantitative measure of the base strength in IL solutions and compared with the relative constants in water.

Optimizing the Interactions of Surfactants with Graphitic Surfaces and Clathrate Hydrates.

Surfactants are amphiphilic molecules active at the surface/interface and able to self-assemble. Because of these properties, surfactants have been extensively used as detergents, emulsifiers, foaming agents, and wetting agents. New perspectives have been opened by the exploitation of surfactants for their capacity to interact as well with simple molecules or surfaces.

Thermodynamic analysis of anion and cation effects on the keto-enol equilibrium in ionic liquids. A comparative study with conventional solvents.

A comparative thermodynamic investigation of the keto-enol interconversion reaction has been performed in several organic solvents and room-temperature ionic liquids (RTILs) to evaluate the role of the solvent and the effect of the ionic composition of RTILs. The tautomeric constant (KT) values at different temperatures have been analyzed in terms of the van't Hoff relationship to give the relevant thermodynamic parameters. The ΔG° values are the results of quite different combinations of the ΔH° and ΔS° values depending on the nature of the solvent.

Light-driven directed proton transport across the liposomal membrane.

We have developed a simple artificial photoresponsive ion-gating device by inserting molecular switches in the membrane of liposomes. A controlled and directed proton transport across the bilayer membrane can lower the internal pH of the liposomes from neutral to around 4 under combined light and chemical stimulation.

Effect of ring size on the tautomerization and ionization reaction of cyclic 2-nitroalkanones: an experimental and theoretical study.

The keto-enol tautomerism of some cyclic 2-nitroalkanones was studied in cyclohexane. Keto-enol equilibrium constants, K(T), at 25 °C were obtained from (1)H NMR spectra. The relative enol content for the investigated ketones as a function of ring size decreases in the order 6 > 7 > 11 > 12 > 15.

Kinetics of demetallation of a zinc-salophen complex into liposomes.

A Zn-salophen complex has been incorporated into POPC large unilamellar liposomes (LUV) obtained in phosphate buffer at pH 7.4. Fluorescence optical microscopy and anisotropy measurements show that the complex is located at the liposomal surface, close to the polar headgroups.

Characterization of cationic liposomes. Influence of the bilayer composition on the kinetics of the liposome breakdown.

The cationic large unilamellar mixed liposomes from 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and didodecyldimethylammonium bromide (DDAB) or dioctadecyldimethylammonium bromide (DODAB) were prepared. The influence of the addition of Triton X-100 (TX-100) or octaethylene glycol mono-n-dodecylether (C(12)E(8)) on the membrane integrity was investigated turbidimetrically. The stability of the liposomal systems was estimated by monitoring fluorimetrically at 25 °C the rate of spontaneous and surfactant-induced release of entrapped 5(6)-carboxyfluorescein (CF).

Synthesis and aggregation behaviour of a new sultaine surfactant.

The aggregation properties of a new sultaine surfactant have been studied in buffered aqueous solution at pH 7.4 under controlled condition of osmolarity. Spontaneously formed sultaine vesicles with a mean diameter of about 1 μm can be observed by optical microscopy.

Basicity of pyridine and some substituted pyridines in ionic liquids.

The equilibrium constants for ion pair formation of some pyridines have been evaluated by spectrophotometric titration with trifluoroacetic acid in different ionic liquids. The basicity order is the same in ionic liquids and in water. The substituent effect on the equilibrium constant has been discussed in terms of the Hammett equation.

Fine-tuning of POPC liposomal leakage by the use of beta-cyclodextrin and several hydrophobic guests.

The effect of entrapped beta-cyclodextrin (beta-CD) on the stability of multilamellar vesicles (MLVs) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), prepared by the dehydration-rehydration method, was studied by monitoring the release of 5(6)-carboxyfluorescein encapsulated into the liposomes. Different hydrophobic guests, such as Fullerene C(60), have been incorporated into the POPC bilayer in order to modify the membrane composition. The kinetic results as well as ESI-MS measurements evidenced that the destabilizing activity of beta-CD is due to the formation of beta-CD inclusion complexes and the consequent removal of selected bilayer constituents from the liposomal membrane.

The base-catalyzed keto-enol interconversion of 2-nitrocyclohexanone in ionic liquids.

While the solvent effect on the rate of tautomerization of 2-nitrocyclohexanone in several organic solvents appears to depend essentially on the permittivity of the solvent, a different behavior is observed in some ionic liquids. In particular the rate of the reaction in ionic liquids (ILs) is much faster than expected solely on the basis of the permittivity of the studied ILs. However, if more solvent parameters are taken into consideration (namely the polarizability, H-bond acidity, and cohesive pressure of the solvent) one comprehensive linear solvation energy relationship (LSER) for both organic and IL media can be obtained and no special "ionic liquid effect" can be highlighted.

Perturbing effects of chiral stationary phase on enantiomerization second-order rate constants determined by enantioselective dynamic high-performance liquid chromatography: a practical tool to quantify the accessible acid and basic catalytic sites bonded on chromatographic supports.

Second-order rate constants of the diethylamine-promoted enantiomerization of 2-[2-(1-methyl-1H-pyrrol-2-yl)-2-oxo-1-phenylethyl]-isoindole-1,3-dione, a chiral alpha-substituted ketone endowed with high anti-MAO activity type-A, were measured by dynamic high-performance liquid chromatography (DHPLC), stopped-flow high-performance liquid chromatography (sf-HPLC), and a classical method based on enantioselective HPLC as the monitoring tool. The chiral column used in all determinations was the commercial Chiralpak AD. By comparison of the obtained data, perturbing effects of the stationary phase on the DHPLC and sf-HPLC determinations were highlighted and distinguished in indirect (SP(IPC)) and direct (SP(DPC)) type.

Solvent effects on the rate of the keto-enol interconversion of 2-nitrocyclohexanone.

The rates of tautomerization of 2-nitrocyclohexanone (2-NCH) have been measured spectrophotometrically at 25.0 +/- 0.1 degrees C in several organic aprotic solvents and their binary mixtures.