Study of a heteropolyanion-doped poly(5-amino-1-naphthol) film electrode and its catalytic activity

Influence of Reduced Graphene Oxide on the Electropolymerization of 5-amino-1-naphthol and the Interaction of 1,4-phenylene Diisothiocyanate with the Poly(5-amino-1-naphtol)/Reduced Graphene Oxide Composite

A new composite base on reduced graphene oxide (RGO) and poly(5-amino-1-naphthol) (P5A1N) was synthesized by the electrochemical polymerization of 5-amino-1-naphthol (5A1N) in the presence of HClO₄ and H₄SiW₁₂O₄₀ onto the surface of Au electrode covered with the RGO sheets. The linear dependence of the current densities of the anodic and cathodic peaks with the scan rate of the potential range (0; 0.8) V vs. SCE, reported during electropolymerization of 5A1N, indicates an electron transfer that is controlled by diffusion. A covalent functionalization of the RGO sheets with P5A1N is argued by: (i) the simultaneous disappearance of the IR band at 1584 cm^-1 and the appearance of the new IR bands at 812, 976 and 3744 cm^-1, and (ii) the appearance of two Raman lines at 738 and 1428 cm^-1. An application of the RGO sheets covalently functionalized with P5A1N is demonstrated to support 1,4-phenylene diisothiocyanate (PDITC), a compound used as a cross-linking agent for various biological applications. The chemical adsorption of PDITC onto the RGO sheets covalently functionalized with P5A1N, which involves the appearance of new functional groups of the type thiourea, was proven by Raman scattering and IR spectroscopy.

LF, Ferreira CA, Meneguzzi A. Estudo da obtenção através de síntese eletroquímica de poliaminonaftalenos e poliaminoantracenos

Os poliaromáticos são um grupo de polímeros condutores composto por poliaminonaftalenos, poliaminoantracenos, poliaminonaftóis e polinaftoquinonas com a presença de dois ou três anéis aromáticos. Neste trabalho, filmes de poliaminoantraceno (PAA) e 1,5 polidiaminonaftaleno (1,5-PDAN) foram obtidos por eletropolimerização sobre eletrodos de platina, utilizando uma célula de três eletrodos e um único compartimento. Espectroscopia de infravermelho com transformada de Fourier (FTIR) e espectroscopia RAMAN foram usadas para investigar a estrutura do PAA e foi determinada que ela é similar àquela encontrada na polianilina (PAni) e nos poliaminonaftalenos. Estudos do comportamento eletroquímico por voltametria cíclica mostraram que tanto o PAA como o 1,5-PDAN apresentam somente um par redox e que o PAA não tem boa estabilidade à ciclagem repetitiva, ao contrário do 1,5-PDAN. Micrografias obtidas por Microscopia Eletrônica de Varredura mostraram filmes compactos e homogêneos, com estrutura globular para ambos os polímeros.

Electrochemical method for entrapment of oligonucleotides in polymer-coated electrodes

Oligonucleotides were incorporated into conducting films of poly(3, 4-ethylene dioxythiophene) by an electrochemical method that involves two steps. The electrode is first coated with the polymer film by electropolymerization followed by electrooxidation of the formed polymer in the presence of the oligonucleotide. Neutral water soluble polymers such as poly(vinylpyrrolidone) or poly(ethylene glycol) were added to the polymerizing medium resulting in higher incorporation yields of oligonucleotides. The results showed that a payload of about 1.5 nmol/cm2 can be achieved in an 8 micron thick film for an oligomer concentration of about 70 microM in the working solution. Various physical methods were used to analyze the surface of the polymer-coated electrodes. Results showed the presence of domains of varying sizes at the film surface, corresponding to the insertion of the hydrophilic polymer within the matrix of the conductive polymer. The release of entrapped oligonucleotides from the coated film exhibited a three-step profile: a "burst" period during the first 5 min followed by an intermediate and a very slow release period lasting several days. Such polymer films could be exploited as useful reservoirs of biologically active substances for in vivo delivery to targeted tissues. For example, coated stents that can release antiproliferative agents such as antisense oligonucleotides at the site of balloon dilatation may be of interest in the treatment of postangioplasty restenosis.