Studies of small molecules controlled release using hydro-biogel microspheres

BOSIO V.E.; AMALVY J.I.; CASTRO G.R

Ciudad de Hyderabad, India

Congreso; International Congress on Bioprocesses in Food Industries (ICFB-2008) ? The 5th Convention of the Biotech Research Society (BRSI).; 2008

Biotech Research Society (BRSI)

Molecular aggregation and instability of small molecules, e.g. liposoluble vitamins,are common problems required to be solved for the development of next generation ofpharmaceuticals and foods. Stimuli responsive hydrobiogels for control release ofmolecules are becoming increasingly attractive for industry. Alginate (Alg) gels arecommonly used for encapsulation of many compounds and cells. However, alginate gelsare unstable under physiological conditions present in biological fluids and usually arerequired to be combined with other polymers. Among them, guar gum (GG) is a strongthickening galactomannan, and also emulsifier. Using Congo Red (CR) as probe because ofits tendency to aggregate in aqueous solutions and also in organic environments, andhydrobiogel microspheres as depot, controlled release of CR was tested under differentformulations and experimental conditions. Encapsulation of CR in the matrix containingAlg/GG produces a decrease of 1/3 viscosity in biopolymer solution indicating aninteraction between CR and the matrixes. This interaction was confirmed by FTIRspectroscopy by the bathochromic band shift of ?NH2 and ?SO3 groups of CR.The kinetic of CR release was studied changing the Alg/GG ratio from 3/1 to 25/1.The best formulation was determined at Alg/GG: 7/1, concomitantly with the reduction ofsolution viscosity. At pH 1.2 (stomach simulation) the microspheres were stable for 48 hswithout RC decay. However, at pH 6.8 (small intestine) Alg/GG microspheres weredissolved in 20 minutes. Coating microspheres with the microbial biopolymer emulsanincreases at least 3 times the half life of the microspheres.