Amoxicillin-Loaded Polymeric Nanoparticles of Less than 100 nm: Design, Preparation and Antimicrobial Activity Against Methicillin-Resistant Staphylococcus aureus

  • Mahnaz HadizadehEmail author
  • Asma Toraji
Research Paper


Amoxicillin is commonly used to treat a wide range of infections, but its use is limited by a relatively short biological half-life. This study developed a controlled-release amoxicillin nanoformulation and evaluated its antibacterial activity. The nanoparticles were synthesized by ionic gelation method assisted by sonication and characterized by Fourier transformed infrared, scanning electron microscopy and dynamic light scattering. The antibacterial effect was studied using micro-dilution method to determine the minimum inhibitory concentration of nanoparticles. Inhibition zone diameters of nanoformulation were also compared to those of the free amoxicillin. Sonication reduced the average size of nanoparticles by 70%. The encapsulation efficiency was 95 ± 2%. In vitro release studies showed the initial burst release in the first 10 h and continuous slow release up to the end. The antimicrobial results indicated that the amoxicillin-loaded chitosan nanoparticles were more effective than free amoxicillin against methicillin-susceptible- and methicillin-resistant forms of Staphylococcus aureus. The results highlight that the chitosan and sodium tripolyphosphate concentration and the sonication has a significant influence on nanoparticle size. The optimized chitosan nanoparticles with proper size and controlled release of β-lactam antibiotics may be a good candidate for treating antibiotic-resistant Staphylococcus aureus infections.


Drug delivery Amoxicillin Nanoparticles Chitosan Methicillin resistant Staphylococcus aureus 



Financial assistance from Iran National Science Foundation (INSF), Grant no. 94014310 is gratefully acknowledged. The authors sincerely thank Mrs. Zahra Zahedi for help with the DLS experiments.

Author Contributions

MH contributed in conception of the work, study design, conducting the study, manuscript preparation, revising the draft, approval of the final version of the manuscript, and agreed for all aspects of the work. AT contributed in conception of the work, conducting the study, data analysis, revising the draft, approval of the final version of the manuscript, and agreed for all aspects of the work.

Compliance with Ethical Standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Shiraz University 2017

Authors and Affiliations

  1. 1.Department of BiotechnologyIranian Research Organization for Science and Technology (IROST)TehranIran
  2. 2.Pharmaceutical Sciences Branch, Department of Biotechnology, Faculty of Advanced Sciences and TechnologyIslamic Azad UniversityTehranIran

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