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A novel type of ethylene glycol dimethacrylate (EGDMA) cross-linked guar gum oleate- graft- poly(methacrylic acid) (GGO- g -PMAc) hydrogel was prepared as a pH-responsive controlled release carrier for colon-specific drug delivery. The structure of GGO- g -PMAc hydrogel was characterized by FT-IR, 1 H NMR and X-ray diffraction (XRD) analysis. The swelling degree of the GGO- g -PMAc hydrogel at pH 7.4 was found to be higher than that at pH 1.2. The drug release studies performed in pH 7.4 and 1.2 buffer solutions at 37 °C revealed that the rate and amount of drug released from the GGO- g -PMAc hydrogel at pH 7.4 were higher than that at pH 1.2. The MTT assay revealed that there is no noticeable cytotoxicity of GGO- g -PMAc hydrogel at the concentration range of 0–100 μg/ml against the mouse mesenchymal stem cell line (C3H10T1/2). These results suggested that GGO- g -PMAc hydrogel can be a prospective pH-sensitive carrier for colon-targeted drug delivery. [ABSTRACT FROM AUTHOR]

Guar gum succinate − sodium alginate (GGS-SA) beads cross-linked with barium ions were prepared and characterized as a pH sensitive carrier for colon-specific drug delivery. The structure of GGS-SA beads was confirmed by FT-IR spectroscopy. Scanning Electron Microscope (SEM) studies revealed that the drug loaded GGS-SA beads prepared using 2:2 (w/v) weight percent of GGS and SA had a diameter about 1.4 mm and roughly spherical in shape. X-ray diffraction (XRD) studies showed that the peaks corresponding to GGS and SA at 13.5°, 17.5°, 20.2° and 13.5°, 22°, 24.1°, respectively were destroyed in GGS-SA beads which show that these beads are more amorphous in nature. Swelling studies demonstrated the pH-dependent swelling behavior of GGS-SA beads. The beads showed higher swelling degrees in pH 7.4 than that in pH 1.2 due to the existence of anionic groups in the polymer chains. The drug release study showed that the amount of model drug, ibuprofen, released from the GGS-SA beads was higher in pH 7.4 than that in pH 1.2 due to the pH-dependent swelling behavior of the beads. MTT assay revealed that GGS-SA beads at a concentration range of 0–30 μg/ml had no cytotoxic effect on the cultured mouse mesenchymal stem cells (C3H10T1/2). These results suggest that GGS-SA beads can be used as effective colon-specific drug delivery system with pH-dependent drug release ability. [ABSTRACT FROM AUTHOR]

A novel type of pH-sensitive colon-specific controlled drug delivery carrier based on guar gum succinate (GGS) was prepared by reacting guar gum (GG) with succinic anhydride (SA) in the presence of 4-dimethylaminopyridine (DMAP). The formation of GGS was confirmed by FT-IR and 1 H NMR and characterized using XRD techniques. GGS microparticles with 460–740 μm in size were prepared using sodium trimetaphosphate (STMP) as a cross-linking agent. The size and morphologies of GGS microparticles were assessed by scanning electron microscopy (SEM). The swelling degree of the GGS microparticles was found to be higher in pH 7.4 than in pH 1.2. In addition, GGS microparticles showed a pH dependent drug release profile when compared to the GG microparticles. The MTT assay revealed that there is no apparent cytotoxicity of GGS against a mouse mesenchymal stem cell line at a concentration range of 0–200 μg/ml. These results confirm that GGS could be used as a carrier for colon-specific drug delivery. [ABSTRACT FROM AUTHOR]