Carbon dots (C-dots) possess the attractive properties of high stability, low toxicity, good water solubility, simple synthetic routes as well as size and excitation-dependent photoluminescence (PL).The aim of this work was to synthesize photoluminescent C-dots by hydrothermal method using acerola fruit (Malpighiaemarginata) as a row material, since this fruit contains large number of organic molecules. Studies about the optimal synthesis conditions were performed, where these organic molecules were converted into C-dots by hydrothermal carbonization at 180 ºC for 18 h. The C-dots exhibited a green emission light at 459 nm when excited under UV-light ( λ _ex= 370 nm). These nanomaterials were also successfully used to prepare C-dots/poly (vinyl alcohol) luminescent composites (C-dots/PVA). Both C-dots and C-dots/PVA composite films were investigated by using colorimetric visual sensor for Fe³⁺ metal ions detection. The results show that the prepared C-dots and C-dots/poly presented strong green emission light. The emission spectra of above materials were quenched in the presence of Fe³⁺ ions. Thus, highly specific “turn off” fluorescence sensing of Fe³⁺ was achieved using fluorescent C-dots. Regarding, this work describe that the polymeric films as sensors of metallic ions in aqueous solution appears as a new perspectives to design new composite materials.

This communication aims to propose new insights of Nb₂O₅-based coatings on the 316L SS surface with great prospects to be used in the dentistry field as brackets. The Nb₂O₅thin film was incorporated into the 316L SS by using PVD method. For this purpose, the studied system was characterized structurally and morphologically by using AFM, FTIR-IRRAS, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Biological assays were performed using human gingival fibroblast cell-line HGF-1. In agreement with FTIR and Raman results, the XPS technique indicates that Nb is present in an oxidation state assigned to Nb₂O_5.Furthermore, the coatings produced by PVD technique are less toxic and induces less inflammation in gingival cells (cell-line HGF-1), suggesting the strategy of use Nb₂O₅thin film to cover the 316L SS promoted since its protection of the physiological environment to its biocompatibility improvement.

The development of controlled delivery system formulations has received increasing interest in the agriculture area. Tebuthiuron (TBH) is the most commonly used herbicide for weed control in sugar cane and cotton crops. The TBH and some of its metabolites are detected in surface water by leaching process, evidencing contamination and the need for an efficient process to decrease pesticide residues. The development of a controlled system release appears as a good solution. The present investigation aimed to study the development and evaluation of alginate microparticles as a delivery system for the TBH. The calcium alginate microparticles were prepared from the crosslinking of sodium alginate by Ca⁺⁺ containing varied amounts of TBH supplied in CaCl₂ aqueous solution. The particle size and morphological analysis of microparticles were determined by optical microscopy (OM) and by field emission gun scanning electron microscopy (FEG-SEM). The encapsulation efficiency and release of TBH studies was accessed by UV-vis spectroscopy. The results show that the polymeric microparticles containing TBH can be obtained successfully through a simple method and is suitable as a controlled release carrier system for herbicides and can be effective for controlling weeds.