SYNTHESIS, CHARACTERIZATION AND ANTIBACTERIAL ACTIVITY OF ALUMINIUM OXIDE NANOPARTICLES Original Article MANYASREE D. a , KIRANMAYI P. a* , RAVI KUMAR R. V. S. S. N. b a Department of Biochemistry, Acharya Nagarjuna University, Nagarjuna Nagar 522510, India, b Received: 10 Jun 2017 Revised and Accepted: 22 Nov 2017 Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar 522510, India Email: kiranmayikodali@rediffmail.com ABSTRACT Objective: In the present study, synthesized alumina (Al 2 O3) Methods: The synthesis was carried out by coprecipitation method using aluminium sulfate and NaOH as precursors. The synthesized aluminium oxide nanoparticles were characterized by using X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) with nanoparticles were characterized and their antibacterial activity against gram positive and gram negative organisms were studied. Energy Dispersive X-ray Analysis (EDX) techniques. Besides, this study determines the antibacterial activity and minimum inhibitory concentration (MIC) of Al 2 O3 Results: The average crystallite size of Al nanoparticles against gram-positive (Staphylococcus aureus and Streptococcus mutans) and gram-negative (E. coli and Proteus vulgaris) bacteria. 2 O3 nanoparticles was found to be 35 nm by X-ray diffraction. FT-IR spectrum exhibited the peaks at 615 and 636 were assigned to the aluminium oxide stretching. The EDX measurements indicated the presence of Al along with O peaks. It indicates the purity of the sample. The antimicrobial assay revealed that E. coli showed a maximum zone of inhibition (39 mm) at 50 mg/ml concentration of Al 2 O3 Conclusion: In conclusion, aluminium oxide is a good antibacterial agent against both gram positive and gram-negative organisms. nanoparticles. Keywords: Al 2 O3 © 2018 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license ( nanoparticles, XRD, FTIR, SEM, EDX, Antibacterial activity and MIC http://creativecommons.org/licenses/by/4.0/) DOI: http://dx.doi.org/10.22159/ijpps.2018v10i1.20636 INTRODUCTION Nanotechnology is evolving as a rapidly developing area with its application in science and technology for the purpose of engineering new materials at the nanoscale level [1]. Nanoparticles possess different chemical properties when compared to bulk types of similar chemical composition [2]. Metal oxide nanoparticles have exhibited better durability, lower toxicity, higher stability and selectivity when compared to organic compounds [3]. Moreover, the size of such particles is responsible for the changes in their basic physical and chemical properties. These particles exhibits remarkable applications in catalysis, diagnosis, drug delivery, water treatment, cosmetics, semiconductors, sensing and solid oxide fuels [4, 5]. Aluminium oxide nanoparticles have important applications in ceramic industry [6] and can be used as an abrasive material, in heterogeneous catalysis as an absorbent, as a biomaterial and as reinforcements of metal-matrix composites [7, 8]. In recent years, a rapid increase in microbes that are resistant to conventionally used antibiotics has been observed [9]. A reduction in the particle size from ∼10 µm to 10 nm will increase the contact surface area by 10 9 . In this context nanoscale materials have emerged up as novel antimicrobial agents owing to their high surface area to volume ratio and its unique chemical and physical properties [10]. Such a large contact surface is expected to enhance the extent of bacterial elimination [11]. Reactive groups on a particle surface are likely to modify its biological activity. Therefore, changes in surface chemistry and the type of metal oxide nanoparticle are important in terms of microbial toxicity issues [12]. Alumina nanoparticles are thermodynamically stable particles over a wide temperature range. They are corundum like structure with oxygen atoms adopting hexagonal close packing with alumina ions filling two-thirds of the octahedral sites in the lattice [13]. To the best of our knowledge, there is not much significant research work on the antibacterial properties of alumina nanoparticles. So an attempt has been made to investigate the antibacterial activity and minimum inhibitory concentration of Al 2 O3 MATERIALS AND METHODS nanoparticles synthesized by co- precipitation method. Synthesis of alumina nanoparticles The alumina nanoparticles were prepared by coprecipitation method using aluminium sulfate and sodium hydroxide precursors. Aluminium sulfate, 0.1M, was dissolved in distilled water and the solution was kept under constant stirring using a magnetic stirrer for one hour. After complete dissolution of aluminium sulfate, 0.2M of sodium hydroxide solution was added. The obtained white creamy solution was allowed to settle for an overnight and the supernatant was then discarded carefully. The precipitate was washed several times using distilled water, then dried at 80 °C for overnight. During drying, complete conversion of aluminium hydroxide into alumina takes place. Characterization The X-ray diffraction (XRD) of a powdered sample of Al 2O3 was recorded using an XRD-6100 diffractometer (Shimadzu), and the patterns were recorded with 1.54060 Å Cu Kα radiation. Molecular analysis of the samples was performed by Fourier transform infrared spectroscopy (FT-IR) using IR Affinity-1s (Shimadzu) spectrometer, recorded in the wave number range of 400–4,000 cm- 1 The antibacterial activity of the Al . Morphological study of the nanoparticles was carried out with a scanning electron microscope (SEM) (EVO 18 carlzeiss). 2O3 nanopowder was determined by agar well diffusion method [1] against four microorganisms, E. coli (MCC 2412) and Staphylococcus aureus (MCC2408) were procured from MCC, Pune, India and Proteus vulgaris (MTCC 426) and Streptococcus mutans (MTCC 497) were procured from MTCC, Chandigarh, India. Once the medium was solidified, a suspension of each sample for testing microorganism diluted prior to 10 -1 , 10 -2 and 10 -3 (1 ml of 108 cells/ml) was spread on a solid agar medium in International Journal of Pharmacy and Pharmaceutical Sciences ISSN- 0975-1491 Vol 10, Issue 1, 2018