Research Article Green Fabrication of Copper Nanoparticles Dispersed in Walnut Oil Using Laser Ablation Technique Amir Reza Sadrolhosseini, 1 Suraya Abdul Rashid, 1 Azmi Zakaria, 2 and Kamyar Shameli 3 1 Materials Processing and Technology Laboratory (MPTL), Nanomaterials and Nanotechnology Group, Institute of Advanced Technology, Universiti Putra Malaysia (UPM), 43400 Serdang, Selangor, Malaysia 2 Department of Physics, Faculty of Science, Universiti Putra Malaysia (UPM), 43400 Serdang, Malaysia 3 Malaysia-Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, 54100 Kuala Lumpur, Malaysia Correspondence should be addressed to Amir Reza Sadrolhosseini; amir17984818@gmail.com and Suraya Abdul Rashid; suraya ar@upm.edu.my Received 23 November 2015; Revised 1 February 2016; Accepted 9 February 2016 Academic Editor: Nathan C. Lindquist Copyright © 2016 Amir Reza Sadrolhosseini et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Synthesis of copper nanoparticles was achieved by laser irradiation of copper plate in walnut oil. Te copper plate was irradiated using Nd:YAG pulse laser at diferent ablation time from 5 to 50 minutes, and the prepared samples were characterized using analytical methods to fnd the optical absorption, morphology, particle size, and capping of copper nanoparticles with walnut oil. Consequently, the absorption peak appeared at about 615, 606, 588, 576, and 561 nm; and the nanoparticles formed in spherical shape in walnut oil. Te particle size varied from 25 to 4.01 nm, and the tail of the carbonyl band capped the copper nanoparticles through the electron transfer from the carboxylic group to copper nanoparticles. Te refractive indices of the nanofuid were measured using a surface plasmon resonance technique and changed from 1.4691 + 0.008i to 1.4682 + 0.043i as the volume fraction increased from 0.0257 × 10 −5 to 1.26 × 10 −5 . Consequently, the laser ablation method is environmentally sensitive (i.e., green) and thus is suitable for the fabrication of copper nanoparticles in walnut oil without any agent. 1. Introduction Copper nanoparticles (Cu-NPs) have broad application in industry and medicine due to their physical and chemical properties [1–3]. Te high electrical conductivity of Cu- NPs makes them suitable for applications such as modern electrical circuits, biosensors [4], and sintering additives [5]. Cu-NPs also have other uses including anti-infammatory [6], antioxidative [7], and antiulcer [8] application. In addition, they have been used in medicine to prevent skin photosensi- tivity [9] and nanoprobes. Copper nanoparticles also include considerable localized surface plasmon resonance (LSPR) in the visible region and high surface-enhanced Raman scattering. Many methods including solution phase [10], photo- chemical [11], sonochemical [12], and electrochemical syn- thesis [13] are used to prepare and disperse copper nanopar- ticles in various mediums. Laser ablation introduces a green method for fabricating Cu-NPs [14]. Te preparation of Cu- NPs in water [15], dichloromethane [16], acetonitrile [16], chloroform [16], alcohol [16, 17], and coconut oil [14] using laser ablation has been reported in the literature. Walnut oil contains oleic (18:1), linoleic (18:2), and linolenic (18:3) acids and palmitic acid (c16:1), while concen- trations of other fatty acids such as myristic acid, palmitoleic acid, eicosenoic acid, and stearic acid are very low. However, walnut oil is rich in omega-3 fatty acids, vitamins B-1, B-2, and B-3, vitamin E, and niacin, and the LDL (bad cholesterol) ratio to HDL (good cholesterol) is lower than that with other oils; hence, it is healthier and more helpful than other oils in reducing the risk of coronary artery disease [18]. Walnut oil is used in cooking and skin care because the omega-3 fatty acids it contains have high permeation in human skin and have become popular ingredients in natural skin care products [19]. Hindawi Publishing Corporation Journal of Nanomaterials Volume 2016, Article ID 8069685, 7 pages http://dx.doi.org/10.1155/2016/8069685