Biosynthesis of Silver Nanoparticles Using Licorice Extract and Evaluation of their Antioxidant Activity

This paper presents a simple and eco-friendly method for the synthesis of silver nanoparticles (AgNPs) using licorice (Glycyrrhiza glabra) root extract and the evaluation of their antioxidant activity. UV-Vis spectroscopy, FTIR, TEM and EDX methods were used to characterize the AgNPs. The UV-Vis spectrum shows the characteristic surface plasmon resonance peak at 430 nm. The synthesized AgNPs have a spherical shape and are capped by biomolecules. Furthermore, FTIR spectra and EDX analysis demonstrate the presence of phytochemicals from extract which act as reducing and stabilizing agents. The presence of elemental silver was demonstrated by the peak at 3 keV from EDX spectra. The results following the DPPH free radical scavenging assay suggest that AgNPs present a better antioxidant activity compared to that of the extract. Therefore, the obtained results confirm that licorice represents a source of biomolecules that can be used for synthesizing AgNPs with antioxidant potential.

Aqueous Dispersion of Single-Walled Carbon Nanotubes Using Tetra-Phenyl Bimesitylene Derivative via Noncovalent Modification and Improved Antimicrobial Activity

Tetra-arylbimesityl derivative containing carboxylic groups have successfully been utilized in dispersing single-walled carbon nanotubes (SWNTs) in aqueous solutions through sonication and centrifugation procedures. The dispersion process and the characterization of final stabilized SWNTs were accomplished using analytical techniques, providing sufficient evidences on the preparation of the dispersed SWNTs in water. All the prepared SWNT water dispersions were evaluated for antimicrobial activity against three different reference strains namely Escherichia coli, Staphylococcus aureus and Candida albicans, and have shown considerable selective activity against the Gram-positive strain Staphylococcus aureus.

Novel cyclodextrin-based pH-sensitive supramolecular host–guest assembly for staining acidic cellular organelles

A novel supramolecular approach for the preparation of new non-toxic systems for staining cellular organelles is described.

Etiologic Agents and Antifungal Susceptibility of Oral Candidosis from Romanian patients with HIV-infection or type 1 diabetes mellitus

This is the first Romanian investigation of oral candidosis in patients suffering of HIV-infection or type 1 diabetes mellitus (T1DM). Candida albicans was the dominant species in both types of isolates: n = 14 (46.7%) in T1DM, n = 60 (69.8%) in HIV. The most frequent non-albicans Candida spp. were Candida kefyr (n = 6; 20%) in T1DM and Candida dubliniensis (n = 8; 9.3%) in HIV. Resistance to fluconazole was detected only in the HIV non-albicans Candida group (n = 8; 9.3%). All isolates were susceptible to VOR. The experimental drug MXP had MIC values equal or close to the ones of VOR. Echinocandin resistance was more frequent than azole resistance.

Inclusion complexes of propiconazole nitrate with substituted β-cyclodextrins: the synthesis and in silico and in vitro assessment of their antifungal properties

Inclusion complexes with sulfobutylether-β-cyclodextrin, β-cyclodextrin sulphated sodium salt and monochlorotriazinyl-β-cyclodextrin were characterized and assessed for antifungal activity and cytotoxicity.

Electrochemical evidence for inclusion complexes of thiotriazinone with cyclodextrins

Electrochemical behavior changes due to the formation of inclusion complexes.

Species distribution and susceptibility profile to fluconazole, voriconazole and MXP-4509 of 551 clinical yeast isolates from a Romanian multi-centre study

This is the first multi-centre study regarding yeast infections in Romania. The aim was to determine the aetiological spectrum and susceptibility pattern to fluconazole, voriconazole and the novel compound MXP-4509. The 551 isolates were identified using routine laboratory methods, matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) and DNA sequence analysis. Susceptibility testing was performed using the European Committee for Antimicrobial Susceptibility Testing (EUCAST) method and breakpoints. The yeasts originated from superficial infections (SUP, 51.5 %), bloodstream infections (BSI, 31.6 %) and deep-seated infections (DEEP, 16.9 %), from patients of all ages. Nine genera and 30 species were identified. The 20 Candida species accounted for 94.6 % of all isolates. C. albicans was the overall leading pathogen (50.5 %). Lodderomyces elongisporus is reported for the first time as a fungaemia cause in Europe. C. glabrata and Saccharomyces cerevisiae, as well as the non-Candida spp. and non-albicans Candida spp. groups, showed decreased fluconazole susceptibility (<75 %). The overall fluconazole resistance was 10.2 %. C. krusei accounted for 27 of the 56 fluconazole-resistant isolates. The overall voriconazole resistance was 2.5 % and was due mainly to C. glabrata and C. tropicalis isolates. Fluconazole resistance rates for the three categories of infection were similar to the overall value; voriconazole resistance rates differed: 4 % for BSI, 3.2 % for DEEP and 1.4 % for SUP. The antifungal activity of MXP-4509 was superior to voriconazole against C. glabrata and many fluconazole-resistant isolates. There was a large percentage of non-albicans Candida isolates. A large part of the high fluconazole resistance was not acquired but intrinsic, resulting from the high percentage of C. krusei.

Theoretical study on β-cyclodextrin inclusion complexes with propiconazole and protonated propiconazole

The synthesis of the β-cyclodextrin/propiconazole nitrate inclusion complex and the advantages of the encapsulation of this drug were recently reported, but the experimental data only partially revealed the structure of the supramolecular complex due to the limitations in understanding the intermolecular association mechanism. The present work describes the equilibrium molecular geometries of β-cyclodextrin/propiconazole and β-cyclodextrin/protonated propiconazole, established by the AM1 and PM3 semi-empirical methods. The affinity between different parts of the guest molecule and the cyclodextrin cavity was studied considering that propiconazole possesses three residues able to be included into the host cavity through primary or secondary hydroxyl rims. The results have revealed that the most stable complex is formed when the azole residue of the propiconazole enters the cavity of the cyclodextrin through the narrow hydroxyl’s rim.

Polysiloxane ionic liquids as good solvents for β-cyclodextrin-polydimethylsiloxane polyrotaxane structures

An ionic liquid based on polydimethylsiloxane with imidazolium salt brushes was synthesized as a good solvent for β-cyclodextrin-polydimethylsiloxane rotaxane. As expected the PDMS-Im/Br ionic liquid had a liquid-like non-Newtonian behavior with rheological parameters dependent on frequency and temperature. The addition of rotaxane to the ionic liquid strengthened the non-Newtonian character of the sample and a type of stable liquid-like network was formed due to the contribution of weak ionic interactions. The structure is stable in the 20 to 80 °C domain as proved by the oscillatory and rotational rheological tests.

Synthesis and Characterization of Polyrotaxanes based on Cyclodextrins and Viologen-modified Polydimethylsiloxanes

β-Cyclodextrin ( 1 -CD) and 2 -cyclodextrin ( 2 -CD) (hosts) formed inclusion complexes with 4,41-bipyridinium dication derivatives with long chains (guests), in which the substituents on the bipyridinium nitrogen atoms are 1,3-bis(chloromethylphenethyl)-1,1,3,3-tetramethyldisiloxane. The number of 2 -CD molecules threaded onto the polymer chain increases with the length of the guest chain. In contrast, the number of β-CD molecules threaded onto the polymer is approximately 4 corresponding to each molecular chain, due to the repulsive interaction between β-CD and the quaternary bipyridinium units. The complexes were isolated in high yield and characterized by 1H NMR, 13C NMR, X-ray diffraction, thermal and scanning electron micrographs studies. As proven by X-ray analysis, the synthesized polyrotaxanes are crystalline materials with crystalline patterns significantly different from that of native cyclic oligosaccharide. The thermal stabilities of polyrotaxanes are higher than that of the physical mixture between cyclodextrin and the alternating copolymer, denoting the formation of the inclusion complexes. Scanning electron micrographs of polyrotaxanes reveal cubic and linear shapes without a well formed shape. Shape regularity and geometrical regularities in the agglomerating forms can be observed.

Polyrotaxanes composed of β-cyclodextrin and polydimethylsiloxanes: synthesis, morphology and thermal behavior

Epoxy-terminated polydimethylsiloxanes (E-PDMSs) of different molecular weight Mn were proved to undergo inclusion complexation into the inner cavity of β-cyclodextrin (β-CD), resulting in polyrotaxanes (PRots). The dethreading of the macrocycle was prevented by blocking the siloxane chain with a bulky substituent derived from 4-aminophenyltriphenyl methane (APhTPhM). As revealed by thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy (SEM), wide-angle X-ray diffraction and statistical analysis of SEM images, the thermal properties and the morphology of polyrotoxanes are dependent upon Mn, β-CD/E-PDMS molar ratio and the presence of free β-CD in the complexes.