Antibiotics have a short residence time and have low concentrations when absorbed through the basolateral membrane in the stomach; this causes a failure to enhance drug concentrations at Helicobacter pylori infection sites. This study developed a nanocarrier system with the ability to carry amoxicillin to increase its efficacy against H. pylori. We used a water-in-oil emulsification system to prepare a positively charged nanoemulsion particle composed of amoxicillin, chitosan, and heparin. The particle size of the prepared nanoemulsion particle was controlled by the constituted compositions. The morphology of the nanoemulsion particles was spherical. In vitro analysis of amoxicillin released indicated that the nanocarrier system controlled amoxicillin release in the gastrointestinal dissolution medium and amoxicillin-loaded nanoemulsion particles localized to the site of H. pylori infection. Meanwhile, results of in vivo clearance assays indicated that the prepared amoxicillin-loaded nanoemulsion particles had a significantly greater H. pylori clearance effect in the gastric infection mouse model than the amoxicillin solution alone. (c) 2012 Elsevier Ltd. All rights reserved.