Tansy fruit mediated greener synthesis of silver and gold nanoparticles

Process Biochemistry 45 (2010) 1065–1071 Contents lists available at ScienceDirect Process Biochemistry journal homepage: www.elsevier.com/locate/procbio Tansy fruit mediated greener synthesis of silver and gold nanoparticles Shashi Prabha Dubey a,∗ , Manu Lahtinen b,1 , Mika Sillanpää a,∗∗ a b Laboratory of Applied Environmental Chemistry, Department of Environmental Sciences, University of Eastern Finland, FI-50100, Mikkeli, Finland University of Jyväskylä, Department of Chemistry, P.O. Box 35, FI-40014 JY, Finland a r t i c l e i n f o Article history: Received 29 November 2009 Received in revised form 7 March 2010 Accepted 16 March 2010 Keywords: Tansy fruit extract Metal nanoparticles SPR Zeta potential XRD a b s t r a c t In this paper we have reported the green synthesis of silver (AgNPs) and gold (AuNPs) nanoparticles by reduction of silver nitrate and chloroauric acid solutions, respectively, using fruit extract of Tanacetum vulgare; commonly found plant in Finland. The process for the synthesis of AgNPs and AuNPs is rapid, novel and ecofriendly. Formation of the AgNPs and AuNPs were confirmed by surface plasmon spectra using UV–Vis spectrophotometer and absorbance peaks at 452 and 546 nm. Different tansy fruit extract concentration (TFE), silver and gold ion concentration, temperature and contact times were experimented in the synthesis of AgNPs and AuNPs. The properties of prepared nanoparticles were characterized by TEM, XRD, EDX and FTIR. Finally zeta potential values at various pH were analyzed along with corresponding SPR spectra. © 2010 Elsevier Ltd. All rights reserved. 1. Introduction Science of the nanotechnology is supposed to have started by the lecture of Richard Feyman on “There is Plenty of Room at the Bottom” at the annual meeting of the American Physical Society at the California Institute of Technology in 1959. Due to the optical, magnetic and electrical properties [1,2], nanomaterials have a long list of applicability in improving the human life and its environment. The first relation between human life and nanoscale was developed naturally in ayurveda, which is 5000-year-old Indian system of medicine. It had some knowledge of nanoscience and technology before the term ‘nano’ was even formed, which modern science has just started exploring in the 21st century [3]. Several physical and chemical processes [4–6] for synthesis of metal nanoparticles were developed considering the real life application of nanoparticles in the area of medicine [7], catalysis [8], detection [9], etc. Recently the studies started under green chemistry for the search of benign methods for the development nanoparticles and searching antibacterial, antioxidant, and antitumor activity of natural products. Biosynthetic processes have received much attention as a viable alternative for the development of metal nanoparti- ∗ Corresponding author at: Laboratory of Applied Environmental Chemistry, Department of Environmental Sciences, University of Eastern Finland, FI-50100, Mikkeli, Finland. ∗∗ Co-corresponding author. Tel.: +358 40 355 3410; fax: +358 15 336 013. E-mail addresses: shashiprabhadubey@gmail.com, shashi.dubey@uef.fi (S.P. Dubey), Mika.Sillanpaa@uef.fi (M. Sillanpää). 1 University of Jyväskylä, Department of Chemistry, P.O.Box 35, FI-40014 JY, Finland. 1359-5113/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.procbio.2010.03.024 cles where plant extract is used for the synthesis of nanoparticles without any chemical ingredients [10–14]. Leaf extracts of neem, geranium, hibiscus, cinnamon, tamarind and coriander have also found suitable for the biosynthesis of silver and gold nanoparticles [15–20]. Among various metal nanoparticles, AgNPs and AuNPs have several effective applications as antibacterial, sensors and detectors besides their biomedical applications [21–25]. Tanacetum vulgare (tansy), a perennial herb is also known as Common Tansy, Bitter Buttons, Cow Bitter, Mugwort, or Golden Buttons. Around 1525, it was listed (by the spelling “Tansey”) as “necessary for a garden” in Britain [26]. Tansy was considered a cure for intestinal worms, rheumatism, digestive problems, fevers, sores, measles and less commonly it was used to treat menstrual irregularities and induce menstrual bleeding [27–30]. During the Middle Ages and later, high doses were used to induce abortions [28,31,32]. Contradictorily, tansy was also used to help women conceive and to prevent miscarriages [27,28,33]. Inflorescence of T. vulgare The principal chemical constituent of the herb is the volatile oil or oil of tansy. In addition, a bitter, amorphous principle, tanacetin (C11 H16 O4 ), is present [34] mainly in the flowers. Besides tanacetin, 1066 S.P. Dubey et al. / Process Biochemistry 45 (2010) 1065–1071 Fig. 1. Effect of Tansy fruit extract (TFE) quantity. (a) In silver nanoparticle (AgNPs) synthesis. (b) In gold nanoparticle (AuNPs) synthesis. (c) TEM images of silver and nanoparticles at different leaf extract quantity. (I) S1 AgNPs at 1.8 mL TFE. (II) S2 AgNPs at 2.8 mL TFE. (III) S3 AgNPs at 4.8 mL TFE. (IV) A1 AuNPs at 1.8 mL TFE. (V) A2 AuNPs at 2.8 mL TFE. (VI) A3 AuNPs at 4.8 mL TFE. flower may contain several monoterpenoids [35]. The essential oil content of tansy flowers is about twice as much as in the leaves [36]. According to Leppig [37], the herb also contain the following constituents: tanacetin, tannic acid (tanacetum–tannic acid), traces of gallic acid, volatile oil, a wax-like substance, albuminoids, tartaric, citric, and malic acids, traces of oxalic acid, a laevogyrate sugar, resin, metarabic acid, parabin, and woody fiber. Here we have explored an inventive contribution for synthesis of silver and gold nanoparticles using fruit extract of T. vulgare. The procedure for the development of stable AgNPs and AuNPs is rapid, simple and viable. Synthesized nanoparticles were characterized by various methods, such as TEM, XRD, EDX, UV–Vis and FTIR. 2. Materials and methods Fresh fruits of T. vulgare were collected from Mikkeli city. Silver nitrate and auric acid were obtained from Sigma Aldrich chemicals. All glasswares were properly washed with water and dried in oven. Tansy fruits extract (TFE) was used as a reducing agent for the development of silver and gold nanoparticles. Properly washed 50 g of fresh tansy fruits were added in 250 mL ultrapure water in 500 mL Erlenmeyer flask and boiled for 10–15 min. What- man filter paper (No. 40) was used for the filtration of boiled material to prepare the aqueous fruit extract, which was used as such for metal nanoparticle synthesis. Aqueous solution (1 mM) of silver nitrate and auric acid were prepared and 50 mL of those metal ion solutions were reduced using 1.8 mL of TFE at room temperature for 10 min. Below than this TFE quantity, the solution takes more than 20 min to get a significant SPR for both the metal nanoparticles. As a result brown–yellow and pink–red solutions were formed, indicating the formation of silver and gold nanoparticles, respectively [38,39]. The effects of reaction conditions such as the TFE amount, metal ion concentration, reaction temperature and contact time were also studied. Spectral analysis for the development of nanoparticles at different reaction conditions were observed by UV–Vis spectroscopy (Perkin-Elmer Lamda-45 spectrophotometer). AgNPs and AuNPs gave sharp peak in the range of visible region of the electromagnetic spectrum. Transmission Electron Microscope (TEM) JEM1200EX, JEOL was used for the analysis of size and shape of developed nanoparticles. 3 ␮L of the sample was placed on copper grid making a thin film of sample on the grid and kept for drying at room temperature for 15 min, then extra sample was removed using the cone of a blotting paper and reserved in grid box. The presence of elemental silver and gold was determined using energy dispersive X-ray analysis (EDX) with Zeiss Evo 50 instrument. Zetasizer (Malvern) instrumentation was used to analyze the surface charge and stability of synthesized nanoparticles at pH (2–10). The pH of the solution was maintained by 1N HCl and 1N NaOH. Resulting solutions of the developed nanoparticles of silver and gold were dried at 80 ◦ C for X-ray powder diffraction measurements. The X-ray powder diffrac- S.P. Dubey et al. / Process Biochemistry 45 (2010) 1065–1071 1067 Fig. 2. Effect of metal ion concentration. (a) In AgNPs synthesis. (b) In AuNPs synthesis. (c) TEM images of AgNPs and AuNPs at different metal concentrations. (I) S1 AgNPs at 1 mM silver ion conc. (II) S2 AgNPs at 2 mM silver ion conc. (III) S3 AgNPs at 3 mM silver ion conc. (IV) A1 AuNPs at 1 mM gold ion conc. (V) A2 AuNPs at 2 mM gold ion conc. (V) A3 AuNPs at 3 mM gold ion conc. tion data was acquired by PANalytical X’Pert PRO diffractometer in Bragg–Brentano geometry using step-scan technique and Johansson monochromator to produce pure Cu K␣1 radiation (1.5406 Å; 45 kV, 30 mA). The ICDD PDF2 powder diffraction database [40] implemented in HighScore Plus was used for the search-match phase identification analyses. To estimate crystallite sizes of the produced nanoparticles, most isolated diffraction peak positions were profile fitted using pseudo-Voigt function to establish the full-width at half-maximum values (FWHM) needed for the crystallite size evaluation made by Scherrer method. FTIR spectroscopy measurements were carried out to recognize the bio-groups that bound distinctively on the silver and gold surface and involved in the synthesis of these nanoparticles. Samples for the FTIR were prepared by drying native TFE and resulting TFE with nanoparticles similarly as for powder diffraction measurements. Hand-ground samples were measured by Bruker Tensor 27 FTIR spectrometer in attenuated total reflection mode (Pike Technologies, GladiATR for FTIR with diamond crystal) and using spectral range of 4000–400 cm−1 and resolution of 4 cm−1 . All the samples were analyzed twice to taking into account the potential preparation effects by placing a sample on the diamond crystal. Fig. 3. Effect of temperature. (a) In AgNPs synthesis. (b) In AuNPs synthesis. 1068 S.P. Dubey et al. / Process Biochemistry 45 (2010) 1065–1071 Fig. 4. Effect of contact time. (a) In AgNPs synthesis. (b) In AuNPs synthesis. 3. Result and discussion 3.1. Effects of TFE quantity Different TFE quantities were used for the synthesis of AgNPs and AuNPs. The fruit extract quantity was varied from 0.5, 1.0, 1.8, 2.8, 3.8, 4.8 mL in 50 mL of 1 mM silver nitrate and auric acid solution, respectively. With increase in TFE quantity from 0.5 to 4.8 mL in 50 mL of 1 mM metal ion solution, consistently an increase in peak absorbance was found in UV–Vis spectrum (Fig. 1a and b). Likewise, visual inspection of the solutions revealed color changes from reddish yellow to deep red and light pink to dark pink on both silver and gold solutions with an increase of TFE quantity in each reaction solution. Interpretation of TEM images of AgNPs and AuNPs at 1.8, 2.8 and 4.8 mL of TFE suggests decrease in particle size with an increase in TFE quantity (Fig. 1c). 3.2. Effect of metal ion Surface plasmon resonance spectra for AgNPs and AuNPs were obtained at 452 and 546 nm with brown–yellow and pink–red colors, respectively, at different metal ion concentration (Fig. 2a and b). In case of AgNPs, peak absorbance increases with metal ion concentration from 1 to 3 mM but decreases at 3 mM gold ion concentration in case of AuNPs. TEM images of AgNPs and AuNPs at different metal ion concentrations have been presented in Fig. 2c. The particle size of AgNPs was found larger at higher metal ion concentration and red shift occurred in the SPR spectra which in well correlation with the Mock et al.’s work [41]. In comparison to AgNPs the AuNPs express larger sized nanoparticles which were observed in TEM imaging at higher metal ion concentration. 3.3. Effect of reaction temperature The SPR spectra were taken after 10 min heating of the sample at different temperature. By increasing reaction temperature from 25 to 150 ◦ C, an increase in peak sharpness was found in case of both AgNPs and AuNPs (Fig. 3a and b). It may be due to increasing reaction rate for NPs synthesis [11]. This sharpness in absorbance peak depend on size of the synthesized nanoparticle as with higher temperature, particle size may be smaller, which results into sharpness of the plasmon resonance band of AgNPs and AuNPs [41,42]. Fig. 5. Effect of pH. (a) Zeta potential at different pH. (b) Effect of pH on SPR of AgNPs. (c) Effect of pH on SPR of AuNPs. S.P. Dubey et al. / Process Biochemistry 45 (2010) 1065–1071 1069 3.4. Effect of reaction time Formation of nanoparticles started within 10 min and spectra were recorded after at 10 min, 1, 2, 3, 4 and 5 h. Effect of the reaction time on AgNPs and AuNPs synthesis was also evaluated with UV–Vis spectra and it is noted that with an increase in time the peak become shaper (Fig. 4a and b). The reaction time found for the development of nanoparticles in this study was found significantly lower than in earlier reports [42,43]. 3.5. Effect of pH on NPs stability Zeta potential (ZP) values reveal details about the surface charge and stability of the synthesized silver and gold nanoparticles. At different solution pH, there was little variation in the zeta potential value of AuNPs. However, AgNPs demonstrate lower ZP value at strongly acidic pH, whereas higher values were obtained at more alkaline pH solutions (Fig. 5a). In overall, the results of zeta potential value for AgNPs and AuNPs are −26 and −31 mV, respectively, indicating the stability of the synthesized nanoparticles which was also supported by absorbance peaks in SPR spectra at various pH (Fig. 5b and c). It can be said that at acidic pH, the particle size are comparatively larger than the basic pH, as blue shift was clearly reported in the SPR spectra [41]. Fig. 6. Experimental diffraction patterns of silver and gold nanoparticle samples AgNPs (a), and AuNPs (b). The peak positions of elemental Ag and Au are indicated by  marks and positions of KCl phase by stick plot. ples. No other gold containing compounds than the metallic Au can be recognized from the XRD pattern. The crystallite sizes of the nanoparticles were estimated by the Scherrer method as Eq. (1): 3.6. Characterizations of the nanoparticles D= TEM images showed that particles are mostly triangular and spherical in shape, whereas some particles showed hexagonal shapes as well. The sizes found for NPs are roughly in the range of 10–40 nm (Figs. 1c and 2c). The experimental powder diffraction (XRD) patterns of the prepared silver and gold nanoparticles are shown in Fig. 6. On the XRD pattern of AgNPs, diffraction peaks at 38.13◦ , 44.21◦ , 64.47, 77.37◦ , 81.47◦ , 98.01◦ 110.56◦ and 114.80◦ can be assigned to face-centered cubic (FCC) metallic silver (identified by PDF-2 ref. 40783). Whereas any peaks originating from potential silver oxides cannot be observed. However, two crystalline “impurity” phases can also be identified from the pattern, which are AgCl (31-1238) and KCl (41-1476). In case of gold containing sample, the characteristic diffraction peaks of FCC metallic gold phase (4-0784) at 38.21◦ , 44.39◦ , 64.62◦ , 77.59◦ , 81.75◦ , 98.16◦ , 110.89◦ and 115.27◦ can be observed. Along with the AuNP phase, peak positions corresponding to a highly crystalline potassium chloride phase can be observed. By comparing the XRD patterns containing either AgNPs or AuNPs, the content of crystalline KCl is significantly higher on AuNP than on AgNP sam- K ˇs cos  (1) in which D is the average size of the crystallites, K is the shapedependent Scherrer’s constant correlating to the true shape of crystallite (0.94 is used to correspond spherical crystallites with cubic symmetry);  is the radiation wavelength (1.5406 Å); ˇs is the full peak width (given in radians) caused by structural broadening due to crystallite size subtracted by instrumental broadening obtained by standard material (Si) in identical measurement conditions;  = diffraction angle. The FWHMs of the most isolated peaks at about 38.1◦ (1 1 1), 77.5◦ (3 1 1) and 114.8◦ (4 2 0) in 2 for both AgNPs and AuNPs (structurally isomorphous with silver) were used for size evaluation. Average crystal size of 16 nm was determined for AgNPs, whereas for AuNPs somewhat smaller crystal size of 11 nm was obtained (Table 1). Elemental silver and gold peak found in the EDX study which is in accordance with the XRD results (Fig. 7). The FTIR spectra of untreated and treated AgNPs and AuNPs samples are shown in Fig. 8. The untreated fruit extract sample show medium or strong absorption bands about at 3281, 2920, 1595, 1260, 1067 cm−1 suggesting –OH [44], aliphatic –CH stretch- Fig. 7. EDX graph of AgNPs and AuNPs. 1070 S.P. Dubey et al. / Process Biochemistry 45 (2010) 1065–1071 Table 1 Average crystal size of AgNPs and AuNPs in samples. Sample Peak position (Miller indices) AgNPs AuNPs Mean value 38.1 (1 1 1) (nm) 77.5 (3 1 1) (nm) 114.8 (4 2 0) (nm) 14 14 17 10 17 10a ◦ ◦ ◦ 16 11 a Calculated from peak 110.9◦ instead of 115.2◦ because of peak overlap with KCl peak. developed nanoparticles and produce a negative surface charge for AgNPs and AuNPs. This simple, low cost and greener method for development of silver and gold nanoparticles may be valuable in environmental, biotechnological and biomedical applications. Acknowledgments The authors are pleased to acknowledge the European Commission (Brussels) for the Marie Curie Research Fellowship for Transfer of Knowledge (No. MTKD-CT-2006-042637) for financial support. References Fig. 8. FTIR spectra of samples before and after the treatment producing AgNPs and AuNPs; TFE (a), TFE + AgNPs (b), and TFE + AuNPs (c). Spectra are shifted on y-axis due to clarity. ing [45], C O stretching frequency [46] and C–O stretching of esters, ethers, and phenols [47] and symmetric C–O stretching [46]. In case of AuNPs, the OH stretching frequency shifts from 3281 to 3274 cm−1 . Comparison of untreated and the treated spectra suggest that in treated sample C O stretching frequency shift from 1595 to 1652 cm−1 to produce nanoparticles and absorption affected on the carbonyl peak (C O stretching) at 1716 cm−1 as it is clearly stronger in the treated AuNPs compared to the untreated one, on which it is nearly absent. In addition, clearly more absorption occurs on broad spectral range of 1393–1070 cm−1 on a treated gold sample indicating interactions between the gold nanoparticles. In case of the silver containing sample, the spectrum has not changed due to the treatment, as both spectra are in practise identical to each other. Oil of tansy contains variety of terpenes, which may involve in the biosynthesis of AgNPs and AuNPs and act as reducing agent for the reduction of metal ion to metal nanoparticles [48]. Specially the conversion of C O group of the terpenes to –C(O) O group, may be responsible for the reduction of Ag+ and Au+ to Ag0 and Au0 , respectively. 4. Conclusion This spanking new and simple method for biosynthesis of silver and gold nanoparticles offers a valuable contribution in the area of green synthesis and nanotechnology without adding different physical and chemical steps. Tansy fruit extract was prepared and successfully employed for the development of silver and gold nanoparticles with spherical and triangular shapes. Powder diffraction study showed the face-centered cubic lattice of both AgNPs and AuNPs. The average crystal of AgNPs and AuNPs are 16 and 11 nm estimated from Scherrer method. FTIR analysis of native and nanoparticles samples indicate the involvement of carbonyl group in the synthesis and probably the carboxylate ion cover the [1] Bar H, Bhui DK, Sahoo GP, Sarkar P, De SP, Misra A. Green synthesis of silver nanoparticles using latex of Jatropha curcas. 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