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Novel semi-interpenetrating polymer network (IPN) hydrogel microspheres of chitosan (CS) and hydroxypropyl cellulose (HPC) were prepared by emulsion-cross-linking method using glutaraldehyde (GA) as a cross-linker. Chlorothiazide (CT), a diuretic and anti-hypertensive drug with limited water solubility, was successfully encapsulated into IPN microspheres. Various formulations were prepared by varying the ratio of CS and HPC, percentage drug loading and amount of GA. Microspheres were characterized by Fourier transform infrared (FTIR) spectroscopy to investigate the formation of IPN structure and to confirm the absence of chemical interactions between drug, polymer and cross-linking agent. Scanning electron microscopy (SEM) was performed to study the surface morphology of the microspheres. SEM showed that microspheres have smooth surfaces. Particle size, as measured by laser light scattering technique, gave an average size ranging from 199-359 μm. Differential scanning calorimetry (DSC) was performed to know the formation of IPN structure. X-ray diffraction (X-RD) studies were performed to understand the crystalline nature of the drug after encapsulation into IPN microspheres. Encapsulation of drug up to 76% was achieved as measured by UV spectroscopy. Both equilibrium and dynamic swelling experiments were performed in 0.1 N HCl. Diffusion coefficients (D) for water transport through the microspheres were estimated using an empirical equation. In vitro release studies indicated the dependence of release rate on the extent of cross-linking, drug loading and the amount of HPC used to produce the microspheres; slow release was extended up to 12 h. The release data were also fitted to an empirical equation to compute the diffusional exponent (n), which indicated that the release followed the non-Fickian trend. [ABSTRACT FROM AUTHOR]

Sequential interpenetrating networks of poly(methacrylic acid) and poly(vinyl alcohol) have been prepared and cross-linked with glutaraldehyde to obtain pH sensitive microspheres by a water-in-oil emulsification method. Microspheres have been used to deliver the chosen model anti-inflammatory drug viz., ibuprofen to the intestine. Ibuprofen was encapsulated up to 70% within polymeric matrices. The interpenetrating polymer network formed was analysed by Fourier transform infrared spectroscopy. Differential scanning calorimetry and X-ray diffraction analyses were done on drug-loaded microspheres to confirm the polymorphism of ibuprofen. Results of this study indicated the molecular level dispersion of ibuprofen in the developed microspheres. Scanning electron microscopy confirmed the spherical nature and smooth surfaces of the microspheres produced. Mean particle size of the microspheres as measured by laser light scattering ranged between 51-176 μm. Swelling was performed in the simulated gastric as well as the intestinal conditions. Microspheres showed a pulsatile swelling behaviour when pH of the swelling media was altered. The swelling data have been fitted to an empirical equation to understand water transport trends as well as to calculate the diffusion coefficients. Values of diffusion coefficients in acidic media were lower than those found in the basic media. Values of diffusion coefficients decrease with increasing cross-linking of the matrix. In vitro release studies have been performed in 1.2 and 7.4 pH media to simulate the gastric and intestinal conditions. The in vitro release results indicated a dependence on the pH of the release media, extent of cross-linking and the amount of drug loading. The release data were fitted to an empirical relation to estimate the transport parameters and thereby to understand the transport mechanism. [ABSTRACT FROM AUTHOR]

Poly(ether-block-amide) (PEBAX-2533) was used as a polymer matrix and micro-mesoporous activated carbon (AC) particles were chosen as the inorganic fillers in fabricating mixed matrix membranes. Performance of the novel composite membranes, in terms of selectivity towards CO2, was investigated as a function of feed pressure and carbon loading. Membranes were characterized by scanning electron microscopy (SEM) to study their surface and cross-sectional morphologies. Wide-angle X-ray diffraction (WAXD) studies were performed to check if the AC particles interacted with the polymer and also to understand the separation mechanisms. Gas permeance of CO2 and CH4 was determined for 50% and 100% carbon-loaded PEBAX-2533 membrane using an indigenously built high-pressure gas separation manifold. PEBAX-2533-AC membranes exhibited an increase in CO2 gas permeance with increasing carbon loadings in the mixed matrix membranes. [ABSTRACT FROM AUTHOR]

Blend microspheres of chitosan (CS) and guar gum (GG) have been prepared using the water-in-oil (w/o) emulsion method. Cefadroxil was loaded into the microspheres and cross-linked with glutaraldehyde, leading to the formation of a semi-interpenetrating polymer network (IPN) structure. The microspheres have been characterized by scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. Scanning electron micrographs showed the formation of non-uniform microspheres with the rough surface. X-ray diffraction and differential scanning calorimetry studies of the plain and the drug-loaded microspheres indicated that drug is dispersed at the molecular level in the semi-IPN matrix. In vitro dissolution experiments performed in pH 7.4 buffer medium indicated a sustained and controlled release of cefadroxil from semi-IPN microspheres up to 10 h. The amount of drug loaded into microspheres, CS-GG composition of the blend and the amount of cross-linking agent used have shown dependencies on the release of cefadroxil from the semi-IPN microspheres. [ABSTRACT FROM AUTHOR]