Biocompatible electrochemical devices are challenging to develop due to the toxicity of many advanced electrode materials and the difficulty to degrade the discarded material. Few recent advances were made in the synthesis of conducting biodegradable composites of polymers for electrode materials. In this article we describe the synthesis of two new inorganic/organic nanocomposites of Au nanoparticles and conducting polymers based on the biodegradable polymer poly(D,L-lactic acid) (PDLLA): Au nanoparticles/oligomers of 3,4-ethylenedioxythiophene (EDOT)-PDLLA and Au nanoparticles with poly(3,4-ethylenedioxythiophene) (PEDOT)-PDLLA. The nanocomposites were carefully analyzed; the gold nanoparticles mean sizes were 8 ± 3 and 7 ± 2 nm, respectively. 1H and 13C nuclear magnetic resonance (NMR) demonstrated the polymerization of EDOT-PDLLA made through one-pot reaction with AuIII precursor. Raman spectra show that PEDOT-PDLLA is formed in the synthesis of Au/PEDOT-PDLLA. The immobilization of Au/PEDOT-PDLLA on glassy carbon electrodes is easy and more stable than the immobilization of simple PEDOT. Au/PEDOT-PDLLA catalyzes the reduction of H2O2(aq), which was detected by chronoamperometry. The sensor is stable and presents sensitivity of 8.36 × 10-3 A mol-1 L cm-2, linear range of 1-45 mmol L-1 and limit of detection of 0.17 mmol L-1.

ABSTRACT Proteins have been the subject of electrochemical studies. It is possible to apply electrochemical techniques to obtain information about their structure due to the presence of five electroactive amino acids that can be oriented to the outside of the peptidic chain. These amino acids are L-Tryptophan (L-Trp), L-Tyrosine (L-Tyr), L-Histidine (L-His), L-Methionine (L-Met) and L-Cysteine (L-Cys); their electrochemical behavior being subject of extensive research, but it is still controversial. No spectroscopic investigations have been reported on L-Trp, and due to the short life time of the intermediates, ex situ techniques cannot be employed, leading to a never-ending discussion about possible intermediates. In the L-Tyr and L-His cases, spectroelectrochemical studies were performed and different intermediates were observed, suggesting that some intermediates may be observed under specific conditions, as proposed for L-Cys. This amino acid is the most interesting among the electroactive ones because of the presence of a thiol moiety at its side chain, leading to a wide range of oxidation states. It can adsorb onto surfaces of different crystallographic orientation in stereoselective conformation, modifying the surface for different applications.as a surface engineering tool since it plays the role of as an anchor for the growing of nanocrystals inside proteic templates.

Blendas formadas pela polimerização eletroquímica de pirrol em matriz de acrilamida (hidrogel) foram utilizadas, neste trabalho, como dispositivos para a liberação controlada de drogas. A influência de vários parâmetros nesta síntese, como tipo de matriz de hidrogel e condições de polimerização, foi estudada empregando-se planejamento fatorial fracionário. O objetivo final consistiu na obtenção de um material adequado para liberação baseada no controle de potencial. Para os testes de liberação foi utilizada Safranina, como substância modelo. As curvas de liberação demonstram a potencialidade do uso de tais dispositivos. Estes dispositivos foram também caracterizados por espectroscopia Raman e voltametria cíclica.

Blends formed by electrochemical polymerization of polypyrrole (PPy) into polyacrylamide (PAAm) hydrogels were used as devices for controlled drug release. The influence of several parameters in the synthesis, such as type of hydrogel matrix and polymerization conditions was studied by using a fractional factorial design. The final goal was to obtain an adequate device for use in controlled release tests, based on electrochemical potential control. For controlled release tests, Safranin was used as model drug and release curves (amount of drug vs. time) have shown that these blends are promising materials for this use. The optimized blends obtained were characterized by cyclic voltammetry and Raman spectroscopy.

Quimica Nova and the Journal of the Brazilian Chemical Society are two examples of successful initiatives taken by the Brazilian Chemical Society (SBQ - Sociedade Brasileira de Química), and may serve as models for the scientific societies of developing countries. Pillars of the SBQ, these two periodicals are undeniable demonstrations that idealism, utopia and dignity are the essential ingredients for transforming dreams into reality. Few believed that the Brazilian chemical community would one day have, as it does today, two scientific research periodicals indexed in the principal international data banks.

Some aspects of electrochromism phenomena are presented in this review paper. A deep literature revision about the subject dealing with materials and device configurations developed in the last years, is presented. Great efforts of the scientific community have been done in this field. On the other hand, new electrochomic devices based on reversible deposition of metals are specially emphasized here. These devices present many advantages such as simple operation and construction and they have also shown high cycling rates. These factors make them suitable for application in display industry. In this way, many concepts used in the developement of electrodeposition baths are very useful for the improvement of these new devices; specially, all knowledge about the use of additives for modifying films microstructure and morfology.

Os processos redox da polianilina dopada secundariamente e dopada primariamente pré-aquecidas (150oC, 6-12 horas) foram investigados pela espectroscopia Raman ressonante in-situ. Os espectros Raman do polímero dopado secundariamente mostram uma maior dependência com o aumento do potencial do que o polímero dopado primariamente pré-aquecido. Estes diferentes comportamentos foram atribuídos à presença de diferentes graus de ligações cruzadas nos polímeros. A presença de diferentes quantidades de ligações cruzadas foi confirmada por análise termogravimétrica, espectroscopia UV-vis e voltametria cíclica.

The redox processes of secondarily doped and the pre-heated primarily doped polyaniline (150oC, 6-12 h) were investigated by in-situ resonance Raman spectroscopy. Raman spectra of secondarily doped polymer is more dependent on potential than those observed in the pre-heated primarily doped polymer. These different behaviors were attributed to the presence of different degree of crosslinking in the polymers. The presence of different amounts of crosslinking was confirmed by thermogravimetric analysis, UV-vis spectroscopy and cyclic voltammetry.