Formulation and evaluation of floating mucoadhesive alginate beads for targetingHelicobacter pylori

Objectives: There are various obstacles in the eradication of Helicobacter.pylori (H. pylori) infections, including low antibiotic levels and poor accessibility of the drug at the site of the infection. This study describes the preparation and characterisation of novel floating-mucoadhesive alginate beads loaded with clarithromycin (CMN) for delivery to the gastric mucosa to improve the eradication of this micro-organism. Methods: Calcium alginate beads were prepared by ionotropic gelation. The formulation was modified through addition of oil and coating with chitosan in order to improve floating, mucoadhesion and modify drug release. Key findings: SEM confirmed the sphericity of the beads with X-ray microtomography (XμMT) showing the 3D structure of the beads with the layered internal structure of the bead and the even distribution of the drug within the bead. This formulation combined two gastro-retentive strategies and these formulations produced excellent in vitro floating, mucoadhesive and drug release characteristics. Enhanced stability of the beads in phosphate buffer raises a potential for the modified formulations to be targeted to regions of higher pH within the gastrointestinal tract with a higher pH. Drug release from these beads was sustained through an unstirred mucin layer simulating in vivo conditions under which the H. pylori resides in the gastric mucosa. Conclusions: This novel formulation will ensure retention for a longer period in the stomach than conventional formulations and control drug release, ensuring high local drug concentrations, leading to improved eradication of the bacteria

Encapsulation-Induced Stress Helps <em>Saccharomyces cerevisiae </em>Resist Convertible Lignocellulose Derived Inhibitors

The ability of macroencapsulated <em>Saccharomyces cerevisiae </em>CBS8066<em> </em>to withstand readily and not readily <em>in situ</em> convertible lignocellulose-derived inhibitors was investigated in anaerobic batch cultivations. It was shown that encapsulation increased the tolerance against readily convertible furan aldehyde inhibitors and to dilute acid spruce hydrolysate, but not to organic acid inhibitors that cannot be metabolized anaerobically. Gene expression analysis showed that the protective effect arising from the encapsulation is evident also on the transcriptome level, as the expression of the stress-related genes <em>YAP1</em>, <em>ATR1</em> and <em>FLR1</em> was induced upon encapsulation. The transcript levels were increased due to encapsulation already in the medium without added inhibitors, indicating that the cells sensed low stress level arising from the encapsulation itself. We present a model, where the stress response is induced by nutrient limitation, that this helps the cells to cope with the increased stress added by a toxic medium, and that superficial cells in the capsules degrade convertible inhibitors, alleviating the inhibition for the cells deeper in the capsule

Evaluation of Chitosan/Alginate Beads Using Experimental Design: Formulation and In Vitro Characterization

Bovine serum albumin-loaded beads were prepared by ionotropic gelation of alginate with calcium chloride and chitosan. The effect of sodium alginate concentration and chitosan concentration on the particle size and loading efficacy was studied. The diameter of the beads formed is dependent on the size of the needle used. The optimum condition for preparation alginate–chitosan beads was alginate concentration of 3% and chitosan concentration of 0.25% at pH 5. The resulting bead formulation had a loading efficacy of 98.5% and average size of 1,501 μm, and scanning electron microscopy images showed spherical and smooth particles. Chitosan concentration significantly influenced particle size and encapsulation efficiency of chitosan–alginate beads (p < 0.05). Decreasing the alginate concentration resulted in an increased release of albumin in acidic media. The rapid dissolution of chitosan–alginate matrices in the higher pH resulted in burst release of protein drug