Ultrasonic-assisted green synthesis of flower like silver nanocolloids using marine sponge extract and its effect on oral biofilm bacteria and oral cancer cell lines D. Inbakandan a, * , C. Kumar a , M. Bavanilatha b , Dune Naga Ravindra b , R. Kirubagaran c , S. Ajmal Khan d a Centre for Ocean Research, Sathyabama University, Chennai, 600 119, India b Department of Biotechnology, Sathyabama University, Chennai, 600 119, India c Earth System Sciences Organization - National Institute of Ocean Technology, Pallikaranai, Chennai, 600 100, India d Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai, 608 502, India article info Article history: Received 9 April 2016 Received in revised form 18 August 2016 Accepted 18 August 2016 Available online 21 August 2016 Keywords: Ultrasonic Biosynthesis Silver nanoparticles Antibacterial Oral biofilms Oral cancer cells abstract The knowhow followed for synthesis, characterization and application of nanomaterials has become an important branch of nanoscience. The use of marine sponges for the synthesis of metal nanoparticles is still in the budding level of current nanobiotechnology. This paper reports a single step one pot biosynthesis utilizing marine sponge (Haliclona exigua) extract as a reducing agent by means of a con- ventional ultrasonic bath on the formation and growth of flower like silver nanocolloids. These silver nanocolloids were characterized through UV visible spectroscopy, High Resolution Transmission Electron Microscope, Fourier Transform Infrared spectroscopy and X-ray Diffractometer. Further, antibacterial activity and antiproliferative activity were done against oral biofilm bacteria and oral cancer cell lines for the biosynthesized flower like silver nanocolloids. Water soluble organic amines were responsible for the syntheses of nanomaterials which have a size range from 100 to 120 nm. An average size of 9.1 mm zone of inhibition was recorded with 10.0 mg of silver nanocolloids against oral biofilm bacteria. The estimated half maximal inhibitory concentration value for flower like silver nanocolloids was 0.6 mg/ml for oral cancer cell lines. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction In recent days, a lot of attention was devoted to study nano- structured materials due to their unique properties and poten- tials. However, the control over particle size and its morphology is still a challenge in science. Colloidal silver is of particular interest because of distinctive properties, such as good conductivity, chemical stability, catalytic and antibacterial activity. Chemical reduction is the most frequently applied method for the prepara- tion of silver nanoparticles as stable, colloidal dispersions in water or organic solvents. Commonly used reductants are borohydride, citrate, ascorbate, and elemental hydrogen. Green synthetic methods include mixed-valence polyoxometallates, poly- saccharide, tollens, irradiation and bioresources. These methods were carried out in water, an environmentally-friendly solvent. The green synthesis of silver nanoparticles involves three main steps, which must be evaluated based on green chemistry perspectives, including (1) selection of solvent medium, (2) selection of envi- ronmentally benign reducing agent, and (3) selection of nontoxic substances for the stability of silver nanoparticles [1]. Nevertheless, these methods usually spend too much time and use high tem- perature and pressures, besides most procedures were reported for the continuous stirring process. In this direction, development of fast and simple methods to prepare silver nanoparticles is still required. Ultrasonic waves have been successfully used in the syntheses of new materials, since they provide smaller particle size and higher surface area than that re- ported by other methods. Sonochemistry uses high power ultra- sonic waves (20 kHz-10 MHz) to promote chemical reactions. The advantages of sonochemical methods are high velocity rates, controllable reaction conditions, capacity to form unique shapes, narrow distributions of particle size and high purity [2]. Despite the * Corresponding author. Tel.: þ91 44 2450 0646, þ91 9965540310 (mobile). E-mail address: inbakandan@gmail.com (D. Inbakandan). Contents lists available at ScienceDirect Microbial Pathogenesis journal homepage: www.elsevier.com/locate/micpath http://dx.doi.org/10.1016/j.micpath.2016.08.018 0882-4010/© 2016 Elsevier Ltd. All rights reserved. Microbial Pathogenesis 99 (2016) 135e141