Congo red as molecular probe to study interactions between biopolymeric gel microspheres and drugs

BOSIO VALERIA E.; BASU SRESEE; CHACON VILLALBA M. ELIZABETH; GÜIDA JORGE A.; MUKHERJEE ARUP; CASTRO, GUILLERMO R

BIORESOURCE TECHNOLOGY

ELSEVIER SCI LTD

Año: 2011 p. 1 - 21

0960-8524

Congo Red was used as molecule model for controlled release studies of antibiotics with aromatic motifs using biopolymers. Guar gum was derivatized to carboxymethyl guar gum in order to improve aqueous solubility and reduce surface tension. The Carboxymethyl guar gum was confirmed by FTIR spectroscopy, and elemental analysis. Surface tension of carboxymethyl guar gum is reduced in about 50 % compared with the native polymer. Viscosimetric studies of 2.0 % biopolymers dissolved in water showed a dramatic decrease from 30,000 cps of guar gum to 350-400 cps for carboxymethyl guar gum indicating pseudoplastic fluid behavior. Gel microsphere composed of 68 % alginate and 32 % carboxymethyl guar gum were found the best blend Congo Red encapsulation. Raman and FTIR spectroscopic analysis of the formulation revealed interaction among Congo Red and the biopolymer matrix attributed mainly to the aromatic motif of the dye with apolar regions of alginate. Controlled release of Congo Red from the gel microspheres under in vitro stomach fluid simulated conditions (pH= 1.2, and 37 °C) showed no release in 25 minutes. However, Congo Red started to be released from the gel microspheres when the pH was increased to 7.4 reaching 62 % in the supernatant in about 8 hours incubation.