July 2019  Vol. 29  No. 7 J. Microbiol. Biotechnol. (2019), 29(7), 1009–1013 https://doi.org/10.4014/jmb.1904.04065 Research Article jmb Special Topic - Antibiotics Potential Antimicrobial Applications of Chitosan Nanoparticles (ChNP) Nur Amiera Syuhada Rozman 1 , Tong Woei Yenn 1 * , Leong Chean Ring 1 , Tan Wen Nee 2 , Muhammad Ariff Hasanolbasori 3 , and Siti Zubaidah Abdullah 1 Universiti Kuala Lumpur, Branch Campus Malaysian Institute of Chemical and Engineering Technology, Lot 1988 Kawasan Perindustrian Bandar Vendor, Taboh Naning, 78000 Alor Gajah, Melaka, Malaysia School of Distance Education, Universiti Sains Malaysia, 11800 Gelugor, Pulau Pinang, Malaysia Nanotechnology and Catalyst Research Centre (Nanocat), University of Malaya, 50630 Kuala Lumpur, Malaysia Introduction Chitosan, a derivative of chitin is a cationic polysaccharide composed of N-acetyl glucosamine and D- glucosamine [1]. Interestingly, chitosan consists of several functional groups which can be modified for numerous applications. Chitosan has been recognized as a versatile biopolymer because of its non-toxicity, biocompatibility, low allergenicity and biodegradability properties [2]. Chitosan is also classified as safe to be used by the US Food and Drug Administration (FDA) for wound dressing applications [3]. However, chitosan is a weak base and it has low solubility in neutral and alkaline media which limits its applications. Nevertheless, this limitation can be overcome by improving the formulation [4]. The most significant characteristic of this biopolymer which makes it able to adhere to the scaffold is the high porosity characteristic [5]. In addition, chitosan is the only biodegradable polymer that exhibits cationic character because of its primary amino groups [6]. Furthermore, chitosan and chitin have been employed as a base material in nanotechnology application. Besides, chitosan shows significant antimicrobial properties because it binds the negatively charged residues of the bacterial cell wall. Electrostatic force between positively charged chitosan promotes a closer interaction with negatively charged bacteria cell wall, that leads to the penetration of drug through the bacteria cell wall. This is because bacterial cell wall is made up with a layer of peptidoglycan which is rich in negatively charged carboxyl and amino groups [7]. So, the potential of chitosan to gather at the site of infection will increase. Chitosan is also able to alter the electron transport chain of bacterial membranes [8]. This system is responsible to generate electron carriers and builds a proton gradient in the inner membrane of mitochondria, which is important for ATP production [9]. The antimicrobial activity of chitosan depends on the type of chitosan, degree of deacetylation and most importantly, the molecular weight [10]. Other Received: April 29, 2019 Revised: June 21, 2019 Accepted: July 8, 2019 First published online July 10, 2019 *Corresponding author Phone: +6016-4822046; Fax: +606-5512001; E-mail: wytong@unikl.edu.my pISSN 1017-7825, eISSN 1738-8872 Copyright © 2019 by The Korean Society for Microbiology and Biotechnology Polymeric nanoparticles are widely used for drug delivery due to their biodegradability property. Among the wide array of polymers, chitosan has received growing interest among researchers. It was widely used as a vehicle in polymeric nanoparticles for drug targeting. This review explored the current research on the antimicrobial activity of chitosan nanoparticles (ChNP) and the impact on the clinical applications. The antimicrobial activities of ChNP were widely reported against bacteria, fungi, yeasts and algae, in both in vivo and in vitro studies. For pharmaceutical applications, ChNP were used as antimicrobial coating for promoting wound healing, preventing infections and combating the rise of infectious disease. Besides, ChNP also exhibited significant inhibitory activities on foodborne microorganisms, particularly on fruits and vegetables. It is noteworthy that ChNP can be also applied to deliver antimicrobial drugs, which further enhance the efficiency and stability of the antimicrobial agent. The present review addresses the potential antimicrobial applications of ChNP from these few aspects. Keywords: Chitosan, nanoparticle drug delivery, chitosan nanoparticle, microbial infection