Contents lists available at ScienceDirect Materials Today Communications journal homepage: www.elsevier.com/locate/mtcomm Synergetic antibacterial potential, dye degrading capability and biocompatibility of Asperagus racemosus root assisted ZnO nanoparticles Panduranga Naga Vijay Kumar Pallela a , Lakshmi Kalyani Ruddaraju b , Sarath Chandra Veerla c , Ravichandra Matangi d , Pratap Kollu e , Shameem Ummey a, *, S.V.N. Pammi f, * a Department of Zoology, Andhra University, Visakhapatnam 530003, India b Shri Vishnu College of Pharmacy, Bhimavaram 530041, A.P, India c Department of Humanities and Basic Sciences, Godavari Institute of Engineering and Technology (Autonomous), Rajahmundry 53329, A.P, India d Department of Chemistry, Indian Institute of Technology Patna, Bihta 801106, Bihar, India e School of Physics, University of Hyderabad, Gachibowli, Hyderabad 500046, India f Department of Materials Science and Engineering, Chungnam National University, Daeduk Science Town, 305-764, Daejeon, South Korea ARTICLE INFO Keywords: Green synthesis Zinc oxide nanoparticles Antibacterial activity Malachite green dye degradation ABSTRACT In recent decades, increasing awareness towards green chemistry has led to a desire to develop an eco-friendly approach for the synthesis of nanoparticles especially through plant-based bio-reduction. Green synthesized metal oxide nanoparticles have received wide interest due to its wide range of applicability as antibacterial agents and photocatalytic dye degradation. In the present study, aiming at green synthesis, Asperagus racemosus root extract mediated zinc oxide nanoparticles (Ar-ZnO NPs) were successfully synthesized and characterized using SEM, XRD, TEM, FTIR and TG-DTA analysis. The prime focus of the study is to explore the combinational antibacterial activity of Ar-ZnO NPs towards both human and fish bacterial pathogens. In addition, efficiency of Ar-ZnO NPs in dye degradation (malachite green) has been demonstrated. The synthesized ZnO nanoparticles have shown spherical and hexagonal particles with a size range of 30−70 nm with a significant fold increase in antibacterial activity in combination with neomycin. Furthermore, HEK cell lines have shown 81 % viability even at a higher concentration of Ar-ZnO NPs (100 ug/mL) indicating biocompatibility. The removal efficiency of Ar-ZnO for MG dye is 93.20 % for 3 h, which represents high dye degrading capacity of synthesized nano- particles. 1. Introduction In the antibiotic resistance era, scientists are in search of new an- timicrobials with modification of existing classes through combina- tional assay. However, there has been no new class of antibiotics dis- covered in past decade [1]. Considering the antibacterial capability of nanoparticles as a new class, there have been recent studies on nano- particles against various gram-positive and gram-negative bacterial pathogens [1–3]. Furthermore, combinational assay of greener nano- particles with standard drugs is of recent interest to admit resistance- free and toxic-free antimicrobials [1,4–6]. Recently various metal oxide nanoparticles are gaining much interest, especially ZnO as it is re- cognized as a safe substance (GRAS) by USFDA and is the essential element for nucleic acid synthesis, neurogenesis, and haemopoiesis along with constituting body tissues [7]. ZnO is profound semi-con- ductor that belongs to group IIeIV with a wide band gap and excitation binding energy of ∼3.2 eV and 60 meV respectively. ZnO NPs possess excellent UV-blocking properties with indegenious multi-tasking ap- plications in antibacterial, wound healing, anti-cancer, bio imaging, drug/ gene delivery, photo- catalytic, and so on [8–10]. By contrast, malachite green (MG) belongs to triphenylmethane compound and used as controversial antibacterial agent (ectoparasiticide and fungicide) in aquaculture and as dye in pigment industry. MG is effective against the oomycete Saprolegnia, which infects fish eggs in commercial aqua- culture. However, apart from its effective action, intake of MG leads to accumulation in fish skin, gills and lungs, which may cause carcino- genic and mutagenic effects in fishes and therefore; in humans through a food chain (zoonotic) [11,12]. Nevertheless, it is the most used dye in fisheries due to its ready availability, efficiency and economical value [12,13]. Considering the photocatalytic and antibacterial activity of ZnO NPs, in the present study, we have chosen fish pathogens along with human pathogens, as consuming infected fish may pose risk to https://doi.org/10.1016/j.mtcomm.2020.101574 Received 18 February 2020; Received in revised form 19 June 2020; Accepted 17 August 2020 ⁎ Corresponding author. E-mail addresses: ummeyshameem@gmail.com (S. Ummey), sreepammi@gmail.com (S.V.N. Pammi). Materials Today Communications 25 (2020) 101574 Available online 19 August 2020 2352-4928/ © 2020 Elsevier Ltd. All rights reserved. T