Colloids and Surfaces B: Biointerfaces 92 (2012) 209–212
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Acaricidal, insecticidal, and larvicidal efficacy of aqueous extract of Annona squamosa L peel as biomaterial for the reduction of palladium salts into nanoparticles Selvaraj Mohana Roopan a,∗ , Annadurai Bharathi a , Rajendran Kumar b , Venkatesh Gopiesh Khanna b , Arunachalam Prabhakarn c a
Organic Chemistry Division, School of Advanced Sciences, VIT University, Vellore 632 014, Tamil Nadu, India Division of Biomolecules and Genetics, School of Biosciences & Technology, VIT University, Vellore 632 014, Tamil Nadu, India c National Institute of Technology, Trichirapalli 620 015, Tamil Nadu, India b
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Article history: Received 24 October 2011 Received in revised form 22 November 2011 Accepted 23 November 2011 Available online 6 December 2011 Keywords: Biosynthesis Annona squamosa L peel Palladium Nanoparticles
a b s t r a c t In recent years the utilization of secondary metabolites from plant extract has emerged as a novel technology for the synthesis of various nanoparticles. In this paper we studied the potential of nanocrystalline palladium nanoparticles production using acaricidal, insecticidal and larvicidal efficacy of Annona squamosa L aqueous peel extract as the biomaterial for the first time. The synthesized nanoparticles were characterized and confirmed as palladium nanoparticles by using UV–visible spectroscopy, XRD and TEM analysis. The results clearly showed that the compounds containing OH as a functional group played a critical role in capping the nanoparticles. Also the results highlight the possibility of green pathways to produce palladium nanoparticles. © 2011 Elsevier B.V. All rights reserved.
1. Introduction In modern nanotechnology, eco-friendly nanoparticles production methods are gaining importance because of the reduction of toxic chemical usage. Now-a-days silver, platinum, gold and palladium metal nanoparticles have tremendous applications in heterogeneous and homogeneous catalysis, optoelectronics, diagnostic biological probes and display devices [1]. Annona squamosa L. (Annonaceae) is well known for its edible tropical fruits, custard apple and mostly distributed in America and Asia. It is reported that this plant possess several medicinal properties [2–4] such as cardiotonic and insecticidal activity etc. In nanoparticles preparation the researcher started to use various sources to control nanoparticles shape and size. There is an increasing interest in the biosynthesis of palladium nanoparticles using plants and microorganisms. In recent years, the bioreduction of noble metallic species using microorganisms has generated more interest among researchers around the world [5]. To synthesize palladium nanoparticles sulphate reducing bacterium Desulfovibrio desulfuricans NCIMB 8307 has been used [6]. But the commercial
∗ Corresponding author. Tel.: +91 09865610356. E-mail address:
[email protected] (S.M. Roopan). 0927-7765/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.colsurfb.2011.11.044
synthesis of metal nanoparticles at industrial scale is unfeasible using microbes as it requires stringent operational conditions and skilled professional. The reduction rate of metal ions by plants has been found to be much faster than the microorganisms. Further the extracellular nanoparticles synthesis using plant extracts would be economical owing to easier downstream processing [7]. Recent findings showed that palladium nanoparticles were synthesized in bulk quantities using coffee and tea extract at room temperature without using surfactant, capping agent and template [8]. Many research groups have been reported the palladium synthesis using various secondary metabolism which is present in the plant of Cinnamon zeylanicum bark [9], Curcuma longa tuber [10]. In this paper, for the first time we studied the potential of nanocrystalline palladium nanoparticles production using agricultural waste A. squamosa L aqueous peel extract as the biomaterial. 2. Materials and methods 2.1. Plant material A. squamosa fruits were collected from in and around Melvisharam (12◦ 56 23 N, 79◦ 14 23 E), Vellore district, Tamil Nadu, India. The taxonomic identification was made by Dr. B. Annadurai, Department of Plant Biology and Biotechnology, C.
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Abdul Hakeem College, Melvisharam, Vellore, India. The voucher specimen was numbered and kept in our research laboratory for further reference. 2.2. Preparation of the extract Fresh peels of A. squamosa were collected, washed thoroughly with double distilled water, air dried and powdered. About 4 g of powdered peel was transferred into a 150 mL beaker containing 40 mL double distilled water, mixed well on a rotary shaker for 1 h. The extract obtained was filtered through Whatman No.1 filter paper and the filtrate was collected in a separate flask.
2.4. Characterization The bioreduction of Pd(OAc)2 in solution was monitored using UV–visible spectrometer (Schimadzu UV spectrophotometer, model UV-1800). Further characterization was done using XRD analysis (Advance Powder X-ray diffractometer, Bruker, Germany model D8) and TEM analysis (Transmission electron microscopy – Hitachi H-7100 using an accelerating voltage of 120 kV and methanol as solvent). 3. Results and discussion 3.1. Nanoparticle composition and size distribution
2.3. Synthesis of palladium nanoparticles Aqueous solution 1 mM of palladium acetate [Pd(OAc)2 ] was freshly prepared with milli Q water and used for the synthesis of palladium nanoparticles. 10 mL of aqueous extract was added to 80 mL of 1 mM Pd(OAc)2 solution. The effect of temperature on the synthesis of palladium nanoparticles was carried out at 60 ◦ C.
The morphology and size of PdNPs in the colloidal solutions and their size distribution were investigated by TEM. TEM images of the precipitated solid phase obtained after termination of the reaction between the A. squamosa aqueous peel extract and Pd(OAc)2 solution are presented in Fig. 1. The nanoparticles are pre-dominantly spherical, the larger nanoparticles shown in Fig. 1a and b.
Fig. 1. TEM micrograph of PdNPs synthesized by Annona squamosa L peel extract (scale bar: 100 nm) (a) Overall measurement of nanoparticles; (b) Single nanoparticle measurement; (c) A histogram of size distribution of PdNPs.
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3.2. UV–visible spectrum of palladium nanoparticles UV–visible spectra of the mixture of A. squamosa L aqueous peel extract–Pd(OAc)2 solution recorded against time of reaction (Fig. 3). The formation of PdNPs was monitored by UV–visible spectroscopy in the 250–800 nm range (Fig. 3). The color of the solution gradually turned from brownish yellow into colorless in 4 h, indicating the generation of PdNPs. 3.3. Chemistry involved in PdNPs formation
Fig. 2. XRD pattern of PdNPs by Annona squamosa L peel extract.
Particle size was determined from the TEM images of the nanoparticles removed from the mixture after 4 h of reaction indicates that particles are distributed in the 80 ± 5 nm range (Fig. 1b) and the average particles size are 100 nm (Fig. 1c). XRD studies also confirmed the presence of crystalline palladium which was coherent with previous reports [11]. A comparison of our XRD spectrum with the earlier report confirmed that the palladium nanoparticles formed in our experiments were in the form of nanocrystals, as evidenced by the peaks at 2 values of 38◦ , 44◦ and 58◦ planes for palladium (Fig. 2). The prepared PdNPs have shown a small peak due to some impurity from the biomaterial at 56.8 was also noticed.
1 H NMR spectrum of A. squamosa L aqueous peel extract is depicted in Fig. 4. The strong signal observed at ı = 4.76–4.81 ppm is due to C H. Signal at ı = 5.35 ppm could be due to aliphatic OH group, whereas the signals appearing between ı = 1.26–1.32 ppm are related to aliphatic C CH2 C groups. Since the signal due to alcoholic group is expected to shift to a higher value if alcoholic and non-alcoholic groups coexist. The small signal at ı = 1.45 is related to aliphatic CH2 groups in saturated cyclic structures or CH groups. Signals at ı = 1.79 and ı = 1.80 ppm could be associated to olefinic CH3 C C or CH3 C O groups, where the latter could also be responsible for the signal at ı = 2.33 ppm. These signals are thought to be due to the CH3 C C group since the signals related to the CH3 C O group is expected to appear at ı > 2.00. The C CH2 C O group can be responsible for the signal at ı = 2.37 ppm. The aldehyde group can be responsible for the signal at ı = 9.76 ppm. It should be noted that no signal appears in the ı = 6–8 ppm and ı = 10–12 ppm ranges in which signals due to aromatic and carboxylic acids are expected, respectively. In order to identify the capping reagent(s) and the molecules responsible for the reduction of palladium ions in A. squamosa L aqueous peel extract GC–MS has been evaluated [12]. It showed that aqueous extract contains compounds having the aldehyde and hydroxyl group as a functional group in the structure [12]. Hence the reaction between broth of A. squamosa L aqueous peel extract and the Pd(II) species might occur according to the following equation.
Fig. 3. (a) UV–visible absorption spectrum of biosynthesized palladium nanoparticles at different time intervals by Annona squamosa L aqueous peel extract; (b) Color changes during PdNPs formation by Annona squamosa L peel extract.
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Fig. 4.
1
H NMR spectra of Annona squamosa L aqueous peel extract.
Hence, water soluble hydroxy functional group containing compounds are reported to be responsible for the reduction of palladium ions and the stabilization of PdNPs. 4. Conclusion Spherical PdNPs of particle sizes ranging from 80 ± 5 nm and the average particles size are 100 nm are obtained using a A squamosa L aqueous peel extract. Acknowledgements We thank the management of VIT University for providing all the facilities to carry out this work. One of the authors Dr. S.M. Roopan thank to Dr. F. Nawaz Khan for his support and encouragement. The authors also acknowledge the NMR support provided by SAIF, IIT madras, to carry out this work.
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