Use of DMA-material pocket to determine the glass transition temperature of nitrocellulose blends in film form.

This work describes an unexploited use of DMA-material pocket to determine the glass transition temperature of blends composed by nitrocellulose and poly(Ɛ-caprolactone) in film form. A total of eight blends were prepared increasing the poly(Ɛ-caprolactone) content and changes in the mechanical properties of the blends were determined by DMA-material pocket. Storage modulus, loss modulus, and tan δ were analyzed as a function of temperature. The blends and each former polymer were also analyzed by FTIR-ATR. By the spectroscopy measurements, the intermolecular interactions between poly(Ɛ-caprolactone) and nitrocellulose in the blend is observed, been an evidence of miscibility. Tg of nitrocellulose and poly(Ɛ-caprolactone), 68 and -52 °C respectively, agree with reported values. Tg of the blends shows a single peak of tan δ between the Tg values of isolated former polymers, reinforcing the good miscibility between them. Finally, Tg of the blends exhibits a logarithmic dependence of PCL content, decreasing as poly(Ɛ-caprolactone) content increases.

Trypanosoma cruzi: evaluation of (-)-cubebin derivatives activity in the messenger RNAs processing.

No fully effective treatment has been developed since the discovery of Chagas' disease. Since drug-resistant Trypanosoma cruzi strains are occurring and the current therapy is effective in the acute phase but with various adverse side effects, more studies are needed to characterize the susceptibility of T. cruzi to new drugs. Pre-mRNA maturation in trypanosomatids occurs through a process called trans-splicing, which is unusual RNA processing reaction, and it implies the processing of polycistronic transcription units into individual mRNAs; a short transcript spliced leader (SL RNA) is trans-spliced to the acceptor pre-mRNA, giving origin to the mature mRNA. Cubebin derivatives seem to provide treatments with less collateral effects than benznidazole and showed similar or better trypanocidal activities than benznidazole. Therefore, the cubebin derivatives ((-)-6,6'-dinitrohinokinin (DNH) and (-)-hinokinin (HQ)) interference in the mRNA processing was evaluated using T. cruzi permeable cells (Y and BOL (Bolivia) strains) following by RNase protection reaction. These substances seem to intervene in any step of the RNA transcription, promoting alterations in the RNA synthesis, even though the RNA processing mechanism still occurs. Furthermore, HQ presented better activity against the parasites than DNH, meaning that BOL strain seems to be more resistant than Y.

Dextrin-microencapsulated porphyrin: luminescent properties.

Photophysical properties of porphyrins in aqueous solutions are strongly affected by aggregation. One possible solution to this problem is to encapsulate the porphyrin into polymeric spheres, to provide an environment where the photosensitizer can be administered in its monomeric form in such treatments as photodynamic therapy. Here we report the microencapsulation of the meso-tetrakis(4-sulphonatophenyl) porphyrin (TPPS(4)) photosensitizer by the ultrasonic spray-drying technique. The encapsulated TPPS(4) was morphologically characterized by scanning electron microscopy, and its photophysical properties were studied and compared with those of a physical blend of dextrin and TPPS(4). We successfully encapsulated TPPS(4) into dextrin microspheres, and the encapsulated photosensitizer displays higher luminescence intensity than that of the prepared physical blends.

Europium luminescent polymeric microspheres fabricated by spray drying process.

The spray drying method was used to prepare luminescent microspheres. These microspheres were prepared by spraying an aqueous solution of dextrin and an europium(III) complex with subsequent drying in a hot medium. The spray dried powder was characterized by scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). Particle size distribution was estimated from SEM images. The ultrasonic spray drying technique was successfully applied to yield a microparticulated and red luminescent powder composed by the [Eu(dpa)(3)](3-) (dpa = dipicolinic acid) complex incorporated in dextrin microspheres.