Polymer functionalized nanostructures for antibacterial application

• Main Author: Pu, Lu
• Other Authors: Duan Hongwei
• Format: Theses and Dissertations
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Materials::Biomaterials
• Online Access: http://hdl.handle.net/10356/72077
• Institution: Nanyang Technological University

Bacterial infection and contamination are of great concern for a wide spectrum of consumer and industrial applications ranging from healthcare, cosmetics and food products to water and maritime industry. While antibiotics remain the primary measure for bacterial control, the increasing emergence of superbugs that develop resistance to antibiotics by genetic mutation creates a formidable challenge in this field, stimulating considerable interest in developing alternative antibacterial materials. The purpose of this research is to take advantages of polymer-functionalized nanostructures for antibacterial applications. Due to dramatically enhanced surface area to volume ratio of nanomaterials, functionalized nanoparticles not only show superior antibacterial performance but also possess the ability to assemble into various structures. On one hand, nanomaterials serve as scaffolds for grafting abundant and distinct polymers to enlarge localized charge density of polymers, a critical factor in antibacterial material preparation, or to assemble into distinct structures for drug loading. On the other hand, intrinsic characteristics of nanomaterials may be employed into the killing system, such as hyperthermia effect and magnetic separation ability. Hence, firstly we prepared poly(4-vinylpyridine) functionalized GO and quaternized them by different alkyl chains. The composites were not only effective for microbial control in solution, but were facile to be modified into paper form to execute toxicity. Secondly, we synthesized biodegradable cationic polycarbonates and subsequently grafted them onto superparamagnetic nanoparticles. The materials display synergetic killing effect. On one hand, cationic polymers interacted with cell membrane and led to membrane destruction. On the other hand, the superparamagnetic core generated enough heat to kill bacteria under alternating magnetic field. The combined effect reached higher activity against bacteria. Thirdly, considering polymer based nanoparticles are able to be assembled into vesicles as drug carriers, we successfully synthesized vesicles based on the biodegradable polymer grafted superparamagnetic nanoparticles, encapsulating the antibiotic norfloxacin. The vesicles achieved on- demand drug release to kill bacteria triggered by bacteria secreting lipase. Besides, functionalized with targeted antibody, the vesicles were able to capture the S. aureus and enriched in lower amount of medium, reducing the requirement of material dosage.