The Droplet-Size Effect Of Squalene@cetylpyridinium Chloride Nanoemulsions On Antimicrobial Potency Against Planktonic And Biofilm MRSA

Abstract

Jia-You Fang,1–4,* Yin-Ku Lin,5,6,* Pei-Wen Wang,7 Ahmed Alalaiwe,8 Yu-Ching Yang,1 Shih-Chun Yang9 1Pharmaceutics Laboratory, Graduate Institute of Natural Products, Chang Gung University, Kweishan, Taoyuan, Taiwan; 2Chinese Herbal Medicine Research Team, Healthy Aging Research Center, Chang Gung University, Kweishan, Taoyuan, Taiwan; 3Research Center for Food and Cosmetic Safety and Research Center for Chinese Herbal Medicine, Chang Gung University of Science and Technology, Kweishan, Taoyuan, Taiwan; 4Department of Anesthesiology, Chang Gung Memorial Hospital, Kweishan, Taoyuan, Taiwan; 5School of Traditional Chinese Medicine, Chang Gung University, Kweishan, Taoyuan, Taiwan; 6Department of Traditional Chinese Medicine, Chang Gung Memorial Hospital at Keelung, Keelung, Taiwan; 7Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan; 8Department of Pharmaceutics, College of Pharmacy, Prince Sattam Bin Abdulaziz University, Al Kharj, Saudi Arabia; 9Department of Cosmetic Science, Providence University, Taichung, Taiwan*These authors contributed equally to this workCorrespondence: Shih-Chun YangDepartment of Cosmetic Science, Providence University, 200 Taiwan Boulevard Sec. 7, Shalu, Taichung 433, TaiwanTel [phone] Ext 15041Fax [phone]Email [email protected]: It is important to explore the interaction between antibacterial nanoparticles and microbes for understanding bactericidal activity and developing novel applications. It is possible that the nanoparticulate size can govern the antibacterial potency.Purpose: The purpose of this study was to evaluate the antimicrobial and antibiofilm properties of cetylpyridinium chloride (CPC)–decorated nanoemulsions against methicillin-resistant Staphylococcus aureus (MRSA).Methods: The droplet size could be adjusted by varying the percentage of squalene, the main ingredient of the oily core.Results: We fabricated cationic nanoemulsions of three different sizes, 55, 165, and 245 nm. The nanoemulsions showed greater storage stability than the self-assembled CPC micelles. The tested nanoemulsions exhibited more antimicrobial activity against Gram-positive bacteria than Gram-negative bacteria and fungi. The killing of MRSA was mainly induced by direct cell-membrane damage. This rupture led to the leakage of cytoplasmic DNA and proteins. The nanoemulsions might also degrade the DNA helix and disturb protein synthesis. The proteomic analysis indicated the significant downregulation of DNA-directed RNA polymerase (RNAP) subunits β and β’. The antibacterial effect of nanoemulsions increased with decreasing droplet size in the biofilm MRSA but not planktonic MRSA. The small-sized nanoemulsions had potent antibiofilm activity that showed a colony-forming unit (CFU) reduction of 10-fold compared with the control. The loss of total DNA concentration also negatively correlated with the nanoemulsion size.Conclusion: The present report established a foundation for the development of squalene@CPC nanosystems against drug-resistant S. aureus.Keywords: cetylpyridinium chloride, nanoemulsion, MRSA, biofilm, size effect

Keywords

• cetylpyridinium chloride
• nanoemulsion
• MRSA
• biofilm
• size effect