3D Filaments Based on Polyhydroxy Butyrate-Micronized Bacterial Cellulose for Tissue Engineering Applications.

In this work, scaffolds based on poly(hydroxybutyrate) (PHB) and micronized bacterial cellulose (BC) were produced through 3D printing. Filaments for the printing were obtained by varying the percentage of micronized BC (0.25, 0.50, 1.00, and 2.00%) inserted in relation to the PHB matrix. Despite the varying concentrations of BC, the biocomposite filaments predominantly contained PHB functional groups, as Fourier transform infrared spectroscopy (FTIR) demonstrated. Thermogravimetric analyses (i.e., TG and DTG) of the filaments showed that the peak temperature (Tpeak) of PHB degradation decreased as the concentration of BC increased, with the lowest being 248 °C, referring to the biocomposite filament PHB/2.0% BC, which has the highest concentration of BC. Although there was a variation in the thermal behavior of the filaments, it was not significant enough to make printing impossible, considering that the PHB melting temperature was 170 °C. Biological assays indicated the non-cytotoxicity of scaffolds and the provision of cell anchorage sites. The results obtained in this research open up new paths for the application of this innovation in tissue engineering.

Stationary phase based on cellulose dodecanoate physically immobilized on silica particles for high-performance liquid chromatography.

The chemical agent free preparation of a stationary phase using a natural macromolecule was the focus of this paper. Thermal immobilization of cellulose dodecanoate on silica particles was used for the preparation of a stationary phase without the use of chemical reagents. Cellulose modification was performed to produce a hydrophobic macromolecule with solubility in common organic solvents. The new stationary phase was characterized morphologically and physico-chemically, presenting as spherical particles immobilized with a thin cellulose dodecanoate layer. The degree of substitution of cellulose dodecanoate was 1.7, which resulted in a separation mechanism in reversed phase mode, but with lower hydrophobicity and higher steric selectivity, which are properties from cellulose. These characteristics resulted in a stationary phase with intrinsic selectivity that was able to separate mixtures of polar drugs, homologs of an anionic surfactant and omeprazole isomers, which are not well resolved in typical C18 phases. Considering that cellulose is a natural polymer and the preparation method of stationary phase involves only physical processes of silica modification, the final material presents as a stationary phase with specific retention properties coming from both dodecanoate and cellulose.

Chemically Modified Polyvinyl Chloride for Removal of Thionine Dye (Lauth's Violet).

The chemical modification of hydrophobic polymer matrices is an alternative way to elchange their surface properties. The introduction of sulfonic groups in the polymer changes the surface properties such as adhesion, wettability, catalytic ability, and adsorption capacity. This work describes the production and application of chemically modified polyvinyl chloride (PVC) as adsorbent for dyes removal. Chemical modification of PVC was evaluated by infrared spectroscopy and elemental analysis, which indicated the presence of sulfonic groups on PVC. The chemically modified PVC (PVCDS) showed an ion exchange capacity of 1.03 mmol-1, and efficiently removed the thionine dye (Lauth's violet) from aqueous solutions, reaching equilibrium in 30 min. The adsorption kinetics was better adjusted for a pseudo second order model. This result indicates that the adsorption of thionine onto PVCDS occurs by chemisorption. Among the models for the state of equilibrium, SIPS and Langmuir exhibited the best fit to the experimental results and PVCDS showed high adsorption capacities (370 mg-1). Thus, it is assumed that the system presents homogeneous characteristics to the distribution of active sites. The modification promoted the formation of surface characteristics favorable to the dye adsorption by the polymer.

Characterization and use of Moringa oleifera seeds as biosorbent for removing metal ions from aqueous effluents.

Moringa oleifera seeds were investigated as a biosorbent for removing metal ions from aqueous effluents. The morphological characteristics as well as the chemical composition of M. oleifera seeds were evaluated using Fourier Transform Infrared (FT-IR) Spectroscopy, Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The FT-IR spectra showed the presence of lipids and protein components. Scanning electron micrographs showed that Moringa seeds have an adequate morphological profile for the retention of metal ions. The results suggest that M. oleifera seeds have potential application in Cd(II), Pb(II), Co(II), Cu(II) and Ag(I) decontamination from aqueous effluents.