On-line Method for Montelukast Determination in Bile Salt Medium with Multivariate Optimization and Fluorescent Detection

Journal of Analytical Chemistry - The present development involved a flow injection strategy using a mini-column of multiwalled carbon nanotubes and fluorescent detection (λex of 283 nm,...     

A preliminary assessment of the provenance of ancient pottery through instrumental neutron activation analysis at the Monte Castelo site,Rondônia,Brazil

Journal of Radioanalytical and Nuclear Chemistry - This research aims to contribute to the discussion of ceramic objects found at the Monte Castelo shellmound, an archaeological site located at...     

Quantifying Guest–Host Dynamics in Supramolecular Assemblies to Analyze Their Robustness

The most basic function of synthetic microenvironments for tissue engineering is to act as a physical substrate for cell attachment, migration, and proliferation, similar to the natural cell environment. Functionalization of supramolecular materials with guest compounds that display the same recognition moieties is a common strategy to introduce biofunctionality. However, besides a robust interaction with the material, a certain level of dynamics needs to be conserved for an adaptive interface toward the living environment. A balance between robust material functionalization and dynamic cell interaction needs to be met. The detailed analysis hereof using a ureido‐pyrimidinone (UPy) poly(ethylene glycol) system in dilute and transient network regime is demonstrated. Monovalent and bivalent UPy‐functionalized guest molecules are designed and their interaction with UPy‐host fibers is evaluated. Analysis of guest interaction in the dilute state by microfluidics, and in the gel state, by fluorescence recovery after photobleaching and fluorescence resonance energy transfer is proven to be suitable to quantify the local and ensemble guest mobility. The results demonstrate that the interaction of bioactive moieties through supramolecular host–guest chemistry yields a dynamic system, which is stronger for divalent guests but risks unintended leakage in the case of functional monomeric units.     

The First Study on the Reactivity of Water Vapor in Metal–Organic Frameworks with Platinum Nanocrystals

We first studied the reactivity of H₂O vapor in metal–organic frameworks (MOFs) with Pt nanocrystals (NCs) through the water–gas shift (WGS) reaction. A water‐stable MOF, UiO‐66, serves as a highly effective support material for the WGS reaction compared with ZrO₂. The origin of the high catalytic performance was investigated using in situ IR spectroscopy. In addition, from a comparison of the catalytic activities of Pt on UiO‐66, where Pt NCs are located on the surface of UiO‐66 and Pt@UiO‐66, where Pt NCs are coated with UiO‐66, we found that the competitive effects of H₂O condensation and diffusion in the UiO‐66 play important roles in the catalytic activity of Pt NCs. A thinner UiO‐66 coating further enhanced the WGS reaction activity of Pt NCs by minimizing the negative effect of slow H₂O diffusion in UiO‐66.     

End group polarity and block symmetry effects on cloud point and hydrodynamic diameter of thermoresponsive block copolymers

Thermoresponsive block copolymers are of interest for delivery vehicles in the body. Often an interior domain is designed for the active agent and the exterior domain provides stability in the bloodstream, and may carry a targeting ligand. There is still much to learn about how block sequence and chain end identity affect micelle structure, size, and cloud points. Here, hydrophilic oligo(ethylene glycol) methyl ether acrylate and more hydrophobic di(ethylene glycol) methyl ether methacrylate monomers were polymerized to give amphiphilic block copolymers with amphiphilic chain ends. The block sequence and chain end identity were both controlled by appropriate choice of RAFT chain transfer agents to study the effect of ‘matched’ and ‘mismatched’ chain end polarity with amphiphilic block sequence. The affect of matching or mismatching chain end polarity and block sequence was studied on the hydrodynamic diameter, cloud point, and temperature range of the chain collapse on linear di‐ and triblock copolymers and star diblock polymers. The affects of matching or mismatching chain end polarity were significant with linear diblock copolymers but more complex with triblock and star copolymers. Explanations of these results may help guide others in designing thermoresponsive block copolymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2838–2848     

Cosmetic Formulations with Melaleuca alternifolia Essential Oil for the Improvement of Photoaged Skin: A Double-Blind,Randomized, Placebo-Controlled Clinical Study

This aim of this study was to evaluate the penetration depth, antioxidant capacity and the clinical efficacy of Melaleuca alternifolia pure essential oil and in a nanoemulsion to prevent skin photoaging. For this, 2% of pure essential oil or 2% of this essential oil in a nanoemulsion were vehiculated in a formulation. The skin penetration was evaluated using confocal Raman microspectroscopy. The radical protection factor was evaluated using electron paramagnetic resonance spectroscopy. For a clinical study, 40 male participants, aged 18–28 years, were enrolled, being divided into three groups: vehicle formulation, M. alternifolia pure essential oil and M. alternifolia Nanoemulsion. All the participants also received a sunscreen SPF 50 to use during the day. Before and after 90 days of study, skin hydrolipidics and morphological characteristics were performed by skin imaging and biophysical techniques. The nanoemulsion presented a lower antioxidant capacity and a higher penetration through the stratum corneum, reaching the viable epidermis, improving the stratum granulosum morphology. The groups presented an increase in the papillary depth, improving in the dermis echogenicity and the collagen fibers. Melaleuca alternifolia essential provides the potential to improve photoaged skin, being the application of nanoemulsion able to reach deeper skin layers.