Síntese de nanopartículas à base do polissacarídeo Anadenanthera macrocarpa (angico) como matriz para incorporação de fármacos

• Autor(a) principal: Oliveira, Marilia de Albuquerque
• Data de Publicação: 2010
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/15672
• topic: Polissacarideos; Nanopartículas; Gomas

Polysaccharide nanoparticles obtained from Anadenanthera macrocarpa tree exudates (angico gum, AG) and chitosan (CH) were produced by polyelectrolyte complex formation as well as by graft polymerization of acrylic acid onto a AG backbone. The polyelectrolyte complexes (PECs) were obtained by using AG and its carboxymethylated derivatives with degrees of substitution 0.20 and 0.63 as polianions. Reaction parameters investigated were polymer concentration, molar mass, order of solution addition, charge ratio (n+/n-) and AG degree of substitution of carboxymethylated samples. Data revealed that nanoparticles formed by adding AG to CH (AGCH) are in the range of 17.4 to 41.9 nm. Increasing polyelectrolyte concentration led to a decrease in particle size. Larger sizes were observed for charge ratios (n+/n-) > 1. Regarding the molar mass effect, the higher the chitosan molar mass, the larger are the particle sizes. Atomic Force Spectroscopy revealed that for samples with charge ratio n+/n- = 1, particle sizes were 10 and 14 nm, for high (CHa) and low (CHb) chitosan molar mass, respectively. These figures are lower than those analyzed by light scattering measurements (25.1 and 28.2 nm respectively for AGCHa at n+/n- = 1). Nanoparticles prepared using carboxymethylated AG (CMA) have their sizes strongly dependent on charge ratio; for those samples obtained from CMA with degree of substitution (DS) 0.20 and CHa, size distribution is similar to that of AGCHa samples. For samples synthesized with 0.63 DS, size distribution is dependent on charge ratio: for n+/n-< 0.8 similar distribution is observed as those of AGCHa and CMCHa; for n+/n- > 0.8 larger particles (140 - 636 nm) are produced. CMACHa with 0.63 DS, n+/n- = 4, was used as a matrix for chloroquine encapsulation resulting in a efficiency of encapsulation of 43 %. In vitro release was investigated at pH 5.8 and 7.4, a slower release profile being observed at pH 5.8, whereby only 20 % of drug was released in 22 days. Faster release was observed at pH 7.4, where 84 % of drug was released in 6 h, completion being achieved only after 10 days. Data obtained seem to point out that this system can be used for oral drug administration. AG nanoparticles were also produced by acrylic acid radical polymerization on AG backbone, using cerium ammonium nitrate (CAN) as initiator and methylene bisacrylamide as crosslinking agent. It was investigated the effects of glycosidic unit/acrylic acid (GU/AA) and AA/CAN molar ratios on particle size. AG/AA nanoparticles were found to have sizes in the range 6.4 – 19.4 nm, according to GU/AA ratio and an average reaction yield of 56.6 %. Decreasing initiator concentration resulted in low particle size and high polidispersity. By inserting AA onto AG backbone, smaller particle size was obtained than homopolymer one (417 nm). No pH response was found for AG/AA nanoparticles. Bovine serum albumin (BSA) was doped in AG/AA nanoparticles, with an encapsulation efficiency of 50 % resulting in a low release profile, where 69 % of BSA being released in 30 days.