Preparation of hybrid triple‐stimuli responsive nanogels based on poly(L‐histidine)

A series of novel multi‐responsive disulfide cross‐linked polypeptide nanogels has been synthesized by a one‐step ring‐opening polymerization process. The pH‐responsive core of the prepared nanogels was based on poly(L‐histidine), the difunctional N‐carboxy anhydride of l ‐cystine (l ‐Cys‐NCA) was used as a reduction‐cleavable cross‐linking agent, while the outer hydrophilic corona was comprised of a poly(ethylene oxide) block. Extensive molecular characterization studies were conducted in order to confirm the formation of the desired polymeric nanostructures and also to prove their responsiveness to external stimuli within the physiological values of healthy and cancer tissues. Furthermore, the disruption of the disulfide‐bond linkages between the polymeric chains was achieved by the presence of the reductive tripeptide glutathione (GSH), leading to size variations that were monitored by dynamic light scattering (DLS) and size‐exclusion chromatography (SEC). “Stealth” properties of the formed nanostructures were examined by zeta potential measurements. The described nanogels are clearly promising candidates for drug delivery applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1278–1288     

Antimicrobial activity of the essential oil of Greek endemic Stachys spruneri and its main component, isoabienol

The essential oils of Stachys spruneri Boiss. (sample A and sample B) were analyzed by GC and GC-MS. (+)-Isoabienol was the dominant component (49.5 and 48.2%, respectively of the total oils) among seventy-two identified constituents. Isoabienol was separated, purified by preparative thin-layer chromatography, and further identified by means ofphysicochemical and spectrometric analysis. The microbial growth inhibitory properties of the essential oil and its main metabolite, the labdane diterpene isoabienol, were determined using the broth microdilution method against eight laboratory strains of bacteria (Gram-positive: Staphylococcus aureus, S. epidermidis, Micrococcus luteus, Enterococcus faecalis, Bacillus subtilis, and Gram- negative: Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and two strains of the yeast Candida albicans. Both essential oil and isoabienol showed considerable activity against all the microorganisms tested, with the isolated compound being most active.     

Volatile constituents of different parts of Smyrnium olusatrum from Greece

The essential oils from stems, leaves, inflorescences, and both unripe and ripe infructescences of Smyrnium olusatrum L. (Umbelliferae) collected in Greece were obtained by hydrodistillation and analyzed by GC-FID and GC-MS. Fifty-eight components were identified. Among the samples analyzed, the differences observed were mainly quantitative. All oils were characterized by the abundance of sesquiterpenes. The major components of the stem and leaf oils were furanoeremophil-1-one (54.3% and 28.7%, respectively) and curzerene (18.8%, 29.0%). The main constituents of the inflorescence oil were curzerene (38.1%), germacrone (20.2%) and furanoeremophil-1-one (20.0%), while those of the unripe and ripe infructescence oils were 1beta-acetoxy-furanoeudesm-4(15)-ene (22.1%, 30.8%) and curzerene (29.7%, 17.4%).     

Synthesis of 4-hydroxy-3-[(E)-2-(6-substituted-9H-purin-9-yl)vinyl]coumarins as lipoxygenase inhibitors

The synthesis of 4-hydroxy-3-[(E)-2-(6-substituted-9H-purin-9-yl)vinyl] coumarins has been achieved from the reactions of 4-hydroxycoumarin with 2-(6-substituted-9H-purin-9-yl)acetaldehydes in DMF under heating. The new compounds showed significant lipoxygenase inhibitory activity (e.g., 6a: IC₅₀ = 6.25 μM).     

Mechanical properties and crystallization of high-density polyethylene composites with mesostructured cellular silica foam

In this study, composites of high-density polyethylene (HDPE) with mesostructured cellular foam (MCF) silicas have been prepared by melt mixing and studied for the first time. Two different MCF silica analogues having different pore size were used, i.e., 12 nm (MCF-12) and 50 nm (MCF-50). The MCF content in the mesocomposites was 1, 2.5, 5, and 10 mass%. All HDPE/MCF-50 mesocomposites exhibited improved mechanical properties compared with neat HDPE, indicating that the mesocellular silica foam particles with the large mesopore size can act as efficient reinforcing agents. On the other hand, the MCF-12 silica with the smaller size mesopores induced inferior mechanical properties, mainly due to the poorer dispersion of the silica particles and the formation of large aggregates. The mesocellular silica foam particles also affected the thermal properties and the crystallization characteristics of HDPE. Crystallization of mesocomposites was faster than that of neat HDPE. Crystallization kinetics was analyzed with the Avrami equation for both isothermal and non-isothermal conditions. For isothermal crystallization, the Avrami exponent increased with increasing crystallization temperature from 2 to 3. In non-isothermal crystallization, the values of the Avrami exponent increased from 3 to 6.3 with decreasing cooling rate. Lower activation energy values of non-isothermal crystallization were calculated using the isoconversional method of Friedman, as well as using the Kissinger’s equation. Finally, the nucleation efficiency of the mesocellular silica foam particles was estimated from data associated with non-isothermal crystallization, according to the method of Dobreva.     

Phosphonated fully aromatic polyethers for PEMFCs applications

New homopolymers and copolymers based on aromatic polyethers bearing side diphosphonate and diphosphonic groups have been synthesized. These synthetic efforts resulted in homo and copolymers of high thermal stability but moderate molecular weights. To evaluate the influence of the immobilized phosphonate ester and phosphonic acid moieties on polymer electrolyte membranes for fuel cells applications, blends of the newly synthesized homo and copolymers with a pyridine‐based aromatic polyether were prepared. These blends were miscible with high glass transition temperatures and high thermal stabilities. Furthermore, the introduction of these groups to a polymeric backbone significantly increases the doping ability in phosphoric acid compared to the net matrix as well as the ionic conductivity for high doping levels. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2817–2827, 2010     

Selective corneal imaging using combined second-harmonic generation and two-photon excited fluorescence

A multiphoton microscope employing second-harmonic generation (SHG) and two-photon excited fluorescence (TPF) is used for high-resolution ex vivo imaging of rabbit cornea in a backscattering geometry. Endogenous TPF and SHG signals from corneal cells and extracellular matrix, respectively, are clearly visible without exogenous dyes. Spectral characterization of these upconverted signals provides confirmation of the structural origin of both TPF and SHG, and spectral imaging facilitates the separation of keratocyte and epithelial cells from the collagen-rich corneal stroma. The polarization dependence of collagen SHG is used to highlight fiber orientation, and three-dimensional SHG tomography reveals that approximately 88% of the stromal volume is occupied by collagen lamellae.     

Melatonin/Cyclodextrin Inclusion Complexes: A Review

Melatonin (MLT) is involved in many functions of the human body, mainly in sleeping-related disorders. It also has anti-oxidant potential and has been proven very effective in the treatment of seasonal affective disorders (SAD), which afflict some people during short winter days. Melatonin has been implicated in a range of other conditions, including Parkinson’s disease, Alzheimer’s and other neurological conditions, and in certain cancers. Its poor solubility in water leads to an insufficient absorption that led scientists to investigate MLT inclusion in cyclodextrins (CDs), as inclusion of drugs in CDs is a way of increasing the solubility of many lipophilic moieties with poor water solubility. The aim of this review is to gather all the key findings on MLT/CD complexes. The literature appraisal concluded that MLT inclusion leads to a 1:1 complex with the majority of CDs and increases the solubility of the hormone. The interactions of MLT with CDs can be studied by a variety of techniques, such as NMR, FT-IR, XRD and DCS. More importantly, the in vivo experiments showed an increase in the uptake of MLT when included in a CD.     

Comparative Evaluation of Different Targeted and Untargeted Analytical Approaches to Assess Greek Extra Virgin Olive Oil Quality and Authentication

Extra virgin olive oil (EVOO) is a key component of the Mediterranean diet, with several health benefits derived from its consumption. Moreover, due to its eminent market position, EVOO has been thoroughly studied over the last several years, aiming at its authentication, but also to reveal the chemical profile inherent to its beneficial properties. In the present work, a comparative study was conducted to assess Greek EVOOs’ quality and authentication utilizing different analytical approaches, both targeted and untargeted. 173 monovarietal EVOOs from three emblematic Greek cultivars (Koroneiki, Kolovi and Adramytiani), obtained during the harvesting years of 2018–2020, were analyzed and quantified as per their fatty acids methyl esters (FAMEs) composition via the official method (EEC) No 2568/91, as well as their bioactive content through liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) methodology. In addition to FAMEs analysis, EVOO samples were also analyzed via HRMS-untargeted metabolomics and optical spectroscopy techniques (visible absorption, fluorescence and Raman). The data retrieved from all applied techniques were analyzed with Machine Learning methods for the authentication of the EVOOs’ variety. The models’ predictive performance was calculated through test samples, while for further evaluation 30 commercially available EVOO samples were also examined in terms of variety. To the best of our knowledge, this is the first study where different techniques from the fields of standard analysis, spectrometry and optical spectroscopy are applied to the same EVOO samples, providing strong insight into EVOOs chemical profile and a comparative evaluation through the different platforms.