Abstract
Conventional antibiotic therapies are becoming less efficient owing to the emergence of antibiotic-resistance towards bacteria. The rising numbers of drug-resistant diseases will eventually lead to an “antibiotic apocalypse”. Development of novel antimicrobial material to effectively inhibit or kill microorganism is crucial. Nanoscience and nanotechnology, an emerging field of 21st century might play an important role to combat with these infections. Herein, with this motivation we made an attempt to coat acid-functionalized single-walled carbon nanotubes (AFSWCNTs) onto the paper to explore their interaction mechanism towards gram-positive and gram-negative bacteria by taking advantages of simple and environmentally friendly ultrasound-assisted method (Chapter 2). The fact that not only direct physical contact and piercing action but also AFSWCNTs molecular-scale interactions with bacterial cell membrane play an important role in increasing their accessibility into bacteria through the interaction with peptidoglycan becomes apparent in this study. These findings were well supported by results from attenuated total reflectance-Fourier transform infrared, X-ray photoelectron spectroscopy, and analytical scanning transmission electron microscopy combined with electron energy-loss spectroscopy measurements. We anticipate that the novel antibacterial mechanism by AFSWCNTs might bring a promising strategy to design new antibacterial materials against the drug- bacteria species. On the other hand, there is an urgent need to develop a low-cost, bulk mass production of rapid (within 10 min) and effective (~ 99% killing efficiency) antibacterial material that can combat life-threatening infections. With this motivation, we made an attempt to design a graphene-based photothermal agent, magnetic reduced graphene oxide functionalized with glutaraldehyde (MRGOGA), for efficient capture and effective killing of both gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli) bacteria upon NIR laser irradiation. Furthermore, a comparative photothermal antibacterial property of graphene with its structural sibling i.e. CNTs was studied. We took advantage of the excellent photothermal properties of RGO upon NIR laser irradiation and glutaraldehyde as an efficient capturing agent towards both bacteria. Its magnetic characteristic facilitates the captured bacteria be readily trapped in a small volume by the external magnet. The synergetic effects increase the heating extent by MRGOGA upon NIR laser irradiation and the killing of the captured bacteria. The magnetic and low cytotoxicity properties of MRGOGA make it an ideal candidate for in vivo biomedical applications because of the advantages of easy mobilization at targeted position and minimum cellular damage. In line with the aforementioned work, owing to the graphene’s excellent photothermal properties there are plenty of rooms at the bottom. Graphene-based photothermal anticancer therapy might contribute towards a major hurdle of anticancer therapy i.e. multi-drug resistance.