Nano-Structures & Nano-Objects 24 (2020) 100612 Contents lists available at ScienceDirect Nano-Structures & Nano-Objects journal homepage: www.elsevier.com/locate/nanoso Investigation of antimicrobial activity and cytotoxicity of synthesized surfactant-modified carbon nanotubes/polyurethane electrospun nanofibers Mansab Ali Saleemi a,1 , Phelim Voon Chen Yong a,1 , Eng Hwa Wong b,∗,1 a School of Biosciences, Faculty of Health and Medical Sciences, Taylor’s University Lakeside Campus, 47500 Subang Jaya, Selangor Darul Ehsan, Malaysia b School of Medicine, Faculty of Health and Medical Sciences, Taylor’s University Lakeside Campus, 47500 Subang Jaya, Selangor Darul Ehsan, Malaysia article info Article history: Received 17 August 2020 Received in revised form 17 October 2020 Accepted 21 October 2020 Keywords: Carbon nanotubes Thermoplastic polyurethane Electrospun nanofibers Antimicrobial activity Cytotoxicity abstract Carbon nanotubes (CNTs) are attractive materials because of their excellent physicochemical properties, electrical and thermal conductivity, mechanical strength, and chemical durability. Therefore, CNTs can be used in a wide range of various biological and pharmaceutical sectors. The impact of CNTs- fiber composites on the growth of microbial cells needs to be fully explored. In this work, we have investigated the antimicrobial role of thermoplastic polyurethane (TPU) nanofibers containing various concentrations of surfactant-modified CNTs, such as double-wall (DW) and multi-wall (MW) CNTs against different representative Gram-positive and Gram-negative bacterial and the fungal strains. Be- sides, the cytotoxic effects of synthesized nanofibers were also studied on the human adenocarcinomic lung epithelial cell line (A549). Various concentrations of surfactant-modified CNTs were prepared and then mixed with 10 % solution of polymer (TPU) in N, N-Dimethylformamide (DMF) solvent by using a magnetic stirrer. The prepared solution was passed through the electrospinning apparatus to obtain electrospun nanofibers using a highly stable dispersion. Fourier transform infrared spectroscopy (FTIR) results exhibited that polyurethane polymer was covalently attached to the sidewalls of functionalized CNTs. Further, the morphology of synthesized nanofibers and interaction between pathogens and TPU/f -CNTs fibers were studied by using a field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM) and fluorescence microscopy. In conclusion, the highest rate of microbial growth inhibition was recorded when using the surfactant-modified CNTs concentration of 100 —g/mL with 10 % TPU solution. The antimicrobial activity and cytotoxicity of TPU/f -CNTs nanofibers were both dependent on the treatment time and concentrations. The antimicrobial findings demonstrated the excellent microbicidal and prolonged microbial growth inhibition properties of electrospun nanofibers which propose their applicability as sustained antimicrobial biomaterials. © 2020 Elsevier B.V. All rights reserved. 1. Introduction At present, nanotechnology is a rapidly growing research field that considerably contributes to the improvement of active bio- materials. It is necessary to keep the progress of development at the present pace in order to excel in this field and innovative nanoparticle with unique and novel features are also required. Among several carbon nanomaterials, carbon nanotubes (CNTs) have attracted growing attention by several researchers to work since their discovery by Iijima in 1991 [1] because of their re- markable physicochemical properties and are likely to be applied ∗ Corresponding author. E-mail address: EngHwa.Wong@taylors.edu.my (E.H. Wong). 1 All the authors have contributed equally to the preparation of manuscript draft. in a large number of emerging and existing applications, such as composite materials science [2], electronics [3], water purifica- tion [4], energy storage [5], medical field, and biotechnology [6,7]. The ability of carbon atom can bond itself to form a structure with an extremely low dimension. Carbon can form diverse allotropes based on the formation of either sp 2 or sp 3 bonds between carbon atoms made up of graphite and have been built in cylindrical tubes with several millimeters in length and nanometer-scale in diameter. The arrangement of these atoms at the nanoscale level is particularly substantial where each carbon allotrope displays unique properties. In the field of nanotechnology, researchers have concentrated on their prevalence rate because of the associ- ation with the living tissue and their fate in organisms [8] as well as significance for the environment [9]. In addition, CNTs have triggered a great interest by the re- searchers because of their immense potential as an antibacterial https://doi.org/10.1016/j.nanoso.2020.100612 2352-507X/© 2020 Elsevier B.V. All rights reserved.