1,720,986 research outputs found
Natural and Synthetic Vesicles:Preparation, Interaction with Organic Molecules and Kinetic Effects
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Polymeric Aggregates in Ionic Liquids: the Green Future of the Delivery Systems
No full textThe self-assembly of a series of triblock copolymers Pluronics (P85, P105 and L121) has been investigated in some ionic liquids (BMIMBF4, BMIMPF6 and BMIMTf2N) by using Near-Infrared spectroscopy. The formation of supramolecular structures has been confirmed by optical microscopy. The solvation degree and the aggregation behaviour of P85, P105 and L121 depend on the interactions between the imidazolium ring of the ionic liquid and the hydrophilic moiety of the copolymer. Fluorescent vesicles can be observed after the incorporation of Nile Red into the polymeric bilayer of L121 or by linking fluorescein isothiocyanate to the copolymer structur
Green synthesis and properties of silver nanoparticles in sulfobutylether-β-cyclodextrin aqueous solution
No full textSpherical and monodisperse silver nanoparticles (AgNPs) were obtained in aqueous solution at neutral pH in the presence of sulfobutyl ether β-CD (SBE-βCD) by using an eco-friendly approach. Their stability and size were determined by spectroscopic analysis and light scattering measurements. The SBE-βCD molecules are highly distributed around the AgNPs as observed in the SEM-EDX images and tend to act as stabilizers by preventing their aggregation in solution as suggested by the zeta potential measurements. Furthermore, the dissolution of the investigated nanoparticles was tested by oxidation in the Fenton-like reaction
Polarizability over dipolarity for the spectroscopic behavior of azobenzenes in room-temperature ionic liquids and organic solvents
No full textThe Catalán and Spange empirical solvent parameters scales were applied to the solvatochromismof azobenzene and para-monosubstitued derivatives in a series of solvents. The experimental solvent-dependentwavenumbers of the maximumadsorption band (νmax) were spectrophotometrically determined at 25 °C and compared to the values calculated by multiple linear regression analysis. The results show that polarizability (SP) is the dominant parameter over dipolarity (SdP), solvent acidity (SA) and solvent basicity (SB) in the solute-solvent interactions for the azobenzene derivatives in the investigated media
Combined Liposome–Gold Nanoparticles from Honey: The Catalytic Effect of Cassyopea® Gold on the Thermal Isomerization of a Resonance-Activated Azobenzene
Full text linkGold nanoparticles (AuNPs) have been synthesized directly inside liposomes using honey as a reducing agent. The obtained aggregates, named Cassyopea® Gold due to the method used for their preparation, show remarkable properties as reactors and carriers of the investigated AuNPs. A mean size of about 150 nm and negative surface charge of about -46 mV were determined for Cassyopea® Gold through dynamic light scattering and zeta potential measurements, respectively. The formation of the investigated gold nanoparticles into Cassyopea® liposomes was spectroscopically confirmed by the presence of their typical absorption band at 516 nm. The catalytic activity of the combined liposome–AuNP nanocomposites was tested via the thermal cis–trans isomerization of resonance-activated 4-methoxyazobenzene (MeO-AB). The kinetic rate constants (kobs) determined at 25 °C in the AuNP aqueous solution and in the Cassyopea® Gold samples were one thousand times higher than the values obtained when performing MeO-AB cis–trans conversion in the presence of pure Cassyopea®. The results reported herein are unprecedented and point to the high versatility of Cassyopea® as a reactor and carrier of metal nanoparticles in chemical, biological, and technological applications
An overview on the role of cyclodextrins in the synthesis of silver nanoparticles by chemical reduction
Full text linkThe association between cyclodextrins (CDs) and silver nanoparticles (AgNPs) has been successfully exploited in
a large number of applications. Generally, CDs act as stabilizers, however, their reactivity as reducing agents can
be directly involved in the synthesis of AgNPs. Herein, the most recent results regarding AgNPs prepared by
chemical reduction from native α-, β- and γ-cyclodextrins are reported. The behavior of CDs in host-guest
inclusion complexes onto the metal surface, and the effects on the AgNPs properties have also been examined.
Unlike β-CD/AgNPs and γ-CD/AgNPs, additional reducing agents were required for the investigated α-CD/AgNPs
Learning organic chemistry day by day: The best choice of the best pharmacy students
No full textBackground and purpose
During over ten years of experience in teaching organic chemistry at the Department of Pharmacy we have tried to answer the following question: why do most students tend to take the exam one, two, or more years after the end of the course they have attended? Several reasons could justify this delay, but three seem to be the most common drawbacks for our students: a) time needed for the comprehension of the arguments; b) the number of mandatory exams to pass before organic chemistry; c) lack of a self-evaluation method.
Educational activity and setting
To increase the number of students in the exam sessions of the semester just after the course we have proposed two strategies: 1) a systematic, but stressless, approach by which homework and everyday life examples concerning organic chemistry are used to increase the sense of responsibility in studying; 2) the modification of the number of mandatory exams required for organic chemistry.
Findings
The rate of successful students in the exam sessions at the end of the course increased from 38.3 up to 61.3%. Interestingly, the highest scores tend to be obtained by students in the first session available just after the conclusion of the course.
Discussion and summary
The combined effect of Strategy 1 and Strategy 2 seems to be effective in promoting the learning of organic chemistry and points out that the best performances tend to be associated with students which follow organized studying
Cyclocurcumin as Promising Bioactive Natural Compound: An Overview
No full textAlthough identical in molecular formula and weight, curcumin and cyclocurcumin show remarkable differences in their reactivity. Both are natural compounds isolated from the rhizome of turmeric, the former is involved in the diketo/keto-enol tautomerism through the bis-α,β-unsaturated diketone unit according to the polarity of the solvent, while the latter could react by trans-cis isomerization due to the presence of the α,β-unsaturated dihydropyranone moiety. Even if curcumin is generally considered responsible of the therapeutical properties of Curcuma longa L. due to its high content, cyclocurcumin has attracted great interest over the last several decades for its individual behavior and specific features as a bioactive compound. Cyclocurcumin has a hydrophobic nature characterized by fluorescence emission, solvatochromism, and the tendency to form spherical fluorescent aggregates in aqueous solution. Molecular docking analysis reveals the potentiality of cyclocurcumin as antioxidant, enzyme inhibitor, and antiviral agent. Promising biological activities are observed especially in the treatment of degenerative and cardiovascular diseases. Despite the versatility emerging from the data reported herein, the use of cyclocurcumin seems to remain limited in clinical applications mainly because of its low solubility and bioavailability
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