- Nano Express
- Open Access
Facile Synthesis of Monodisperse Gold Nanocrystals Using Virola oleifera
- Bárbara A. Milaneze1,
- Jairo P. Oliveira1,
- Ingrid Augusto1,
- Wanderson J. Keijok1,
- Andressa S. Côrrea1,
- Débora M. Ferreira1,
- Otalíbio C. Nunes1,
- Rita de Cássia R. Gonçalves1,
- Rodrigo R. Kitagawa1,
- Vinícius G. Celante2,
- André Romero da Silva2,
- Ana Claudia H. Pereira3,
- Denise C. Endringer2, 3,
- Ricardo P. Schuenck1 and
- Marco C. C. Guimarães1Email author
© The Author(s). 2016
- Received: 22 June 2016
- Accepted: 8 October 2016
- Published: 18 October 2016
The development of new routes and strategies for nanotechnology applications that only employ green synthesis has inspired investigators to devise natural systems. Among these systems, the synthesis of gold nanoparticles using plant extracts has been actively developed as an alternative, efficient, cost-effective, and environmentally safe method for producing nanoparticles, and this approach is also suitable for large-scale synthesis. This study reports reproducible and completely natural gold nanocrystals that were synthesized using Virola oleifera extract. V. oleifera resin is rich in epicatechin, ferulic acid, gallic acid, and flavonoids (i.e., quercetin and eriodictyol). These gold nanoparticles play three roles. First, these nanoparticles exhibit remarkable stability based on their zeta potential. Second, these nanoparticles are functionalized with flavonoids, and third, an efficient, economical, and environmentally friendly mechanism can be employed to produce green nanoparticles with organic compounds on the surface. Our model is capable of reducing the resin of V. oleifera, which creates stability and opens a new avenue for biological applications. This method does not require painstaking conditions or hazardous agents and is a rapid, efficient, and green approach for the fabrication of monodisperse gold nanoparticles.
- Gold nanoparticles
- Green synthesis
- Virola oleifera
The emergence of nanotechnology has significantly expanded the applications of nanoparticles by allowing intimate interfaces among materials science, chemistry, physics, and biology to better manipulate and utilize their properties [1, 2]. Several current studies have been devoted to the synthesis, stabilization, and functionalization of gold nanoparticles (AuNPs) [3, 4].
The interest in AuNPs is largely due to the relative ease of their synthesis, which offers good control of their sizes and shapes as well as their optical characteristics. Moreover, the versatile surface chemistry of gold nanoparticles allows them to be coated with a wide range of molecules [5, 6]. Therefore, various applications [7–12] have been integrated into different areas to enable the development of new manufacturing processes [13, 14].
Recently, structural studies of nanoparticles have indicated that chemical synthesis can be replaced by an environmentally friendly process using plant extracts [15–20], in which nanoparticles that are traditionally synthesized in a chemical process are attached to and subsequently released from rigid delivery substrates for biomedical applications [21, 22]. Therefore, the main roles of the plant extract are to act as reducing and capping agents during the synthesis process . Moreover, plant extracts appear to be the best route for the large-scale synthesis of nanoparticles. The green growth of nanoparticles depends on many polyphenol quantities . In this study, gold nanoparticles were synthesized using a V. oleifera extract.
V. oleifera offers numerous distinct advantages, such as biocompatibility, non-toxicity, aqueous solubility, and their beneficial composition that is rich in phenols (i.e., ferulic and gallic acid, epicatechin, tannins, and quercetin) .
Here, we have investigated the design of a new route for the production of gold nanoparticles using a vegetable extract, and the AuNPs produced in this study were distinct from those previously reported [26, 27]. Our method offers several advantages in terms of easy scale-up, environmental friendliness, and low cost. We believe that the broad application of this strategy will contribute to the development of the next generation of green nanotechnology.
Virola oleifera (Schott) A. C. Smith is grown in the Atlantic forest in the southeastern region of Brazil. The plant material was verified by D.Sc. Luciana Dias Thomaz from the Department of Botany, Federal University of Espírito Santo, where the voucher specimen was deposited (VIES 19648). The fluid exudate was obtained by creating a 0.5-m incision in the tree trunk and collecting the resin in an aseptic plastic container, and this resin was transferred to an amber glass vial that was stored at 4 °C prior to analysis. Then, the fluid exudate was subjected to drying at 40 °C followed by grinding to yield 24 g of dried resin.
Experimental Design and Statistical Analysis
Volume of Virola oleifera
Time of the synthesis
The effects of each selected variable on the nanoparticle size were analyzed using STATISTICA version 10.0. The inputs included the absorbance values of the as-prepared samples at 530 nm, and the corresponding diameters were calculated using a trial version of the ImageJ software. An analysis of variance (ANOVA) of the data was also performed, and the values were considered significant at p values <0.05. The optimal values of the independent variables were determined using a three-dimensional analysis of the response surface of the independent and dependent variables.
Gold Nanoparticles Synthesis
To produce AuNPs, we performed a 32 factorial design with 3 levels and 2 variables (Table 1) to investigate the cause and effect relationship between the reducing agent and the time. For the gold nanoparticle synthesis, a 2.5 × 10−4 M gold chloride solution (Sigma-Aldrich, St Louis, MO, USA) was employed, and three percentages of the reducing agent (V. oleifera) were added according to the experimental plan. The plant extract was added to the gold precursor solution. The mixture was maintained at room temperature (25 °C) under stirring (200 rpm) for three time periods (Table 1) and protected from light. The AuNP formation was observed by the appropriate color change.
The electrochemical measurements were carried out using a Metrohm Autolab PGSTAT 128n instrument. Three electrodes were employed. The working electrode was Pt (0.5 cm2), a leak-free saturated Ag/AgCl/KCl electrode was employed as the reference electrode, and the counter electrode consisted of a Pt plate (3.0 cm2).
Characterization of Gold Nanoparticles (UV-Vis, TEM, DLS, SEM, HR-SEM, FTIR, Raman, and X-ray)
A UV-visible spectrophotometer (UV-1800 Shimadzu, Japan) was used to determine the surface plasmon resonance absorption (SPR) by scanning from 400 to 700 nm. For transmission electron microscopy (TEM) visualization, AuNPs were mounted on formvar-coated 200 mesh grids (Ted Pella Inc., USA), negatively stained using an 5 % aqueous uranyl acetate solution (Sigma-Aldrich) and visualized using a transmission electron microscope JEM-1400 (JEOL, São Paulo-SP, Brazil) at 120 kV with lab6 filament. The particle size distribution and zeta potential were determined using dynamic light scattering (DLS) technology (NPA152 Zetatrac, Microtrac Instruments, York, USA) combined with the interaction of random Brownian motion and the driven electric field motion of the particle suspensions. The total mass of the recovered nanoparticles that were obtained after the washing step was suspended in 50 mL of deionized water and sonicated at 50 Hz for a period of 1 min. The zeta potential values represent the average standard deviations for three independent preparations of nanoparticles. The total AuNP concentration was determined using ICP-MS (Perkin Elmer, Optima 7000, USA). The surface, shape, and dispersity characteristics were determined by SEM (JEM 6610-LV, JEOL, São Paulo-SP, Brazil) and HRSEM (Auriga, Zeiss, German). The monodispersity of the AuNPs was determined based on the aspect ratio (length to diameter, L:D) using the ImageJ software (N = 200 nanoparticles). After the AuNP synthesis, the samples were centrifuged at 15,000 rpm for 30 min and freeze-dried using a speed vac. A Fourier transform infrared spectroscopy (FTIR) analysis was performed in ATR mode (FT-MIR FTLA 2000 Bomem) to investigate the interactions between the organic compounds of the V. oleifera extract and the nanoparticles, and the functionalized AuNPs were characterized by Raman spectrometry (ALPHA 300R Confocal Raman Spectrometer) in the 500–3500 cm−1 region at a laser power of 532 nm. Finally, the crystal structure was determined using X-ray diffraction (XRD). The AuNP samples were prepared by drop-coating the pelletized AuNPs on a glass slide and scanning in a 2θ region from 30° to 90° at 0.01° per minute with a time constant of 2 s using a D8 Advance (Bruker-axs) X-ray diffractometer.
Fabrication of Colloidal Gold Nanoparticles and Effects of Two Parameters on AuNP Formation
The influence of the volume of the V. oleifera extract and the reaction time on the formation of AuNPs was evaluated to determine the optimal conditions for this synthesis. We applied a 32 factorial design that was performed by varying the values of the studied parameters, as shown in Table 1. The details of the experimental procedures and characterizations are provided in the “Methods” section.
The relative contributions from the concentration and time to the AuNP growth are presented in a Pareto chart (Fig. 1b). When we independently analyzed the variables, only the concentration resulted in a significant effect (value 7.916) (Fig. 1b). No significant combined effect was observed for the preparation of the nanoparticles. The relative importance of the independent variables was specified by the standardized main effect of the Pareto chart (Fig. 1b). The significance was based on the F values and P values. A larger F value and a smaller P value indicate a more significant variable and corresponding coefficient.
Electrochemical Performance of AuNPs Versus V. oleifera Extract
This process may be related to the initial oxidation. To compare V. oleifera and AuNPs, we focus on the results using a scan rate of 100 mV/s (Fig. 2c). Notably, the gold system undergoes a reduction process that is much more defined. However, the system containing only V. oleifera does not exhibit the same characteristic due to a lack of previous oxidation.
Characterization of Gold Nanoparticles
Gold nanoparticle properties are dependent on their dimensions. Therefore, a monodispersity analysis is important for evaluating the nanoparticles’ synthesis and application. The aspect ratio (D/L) was calculated. As observed in the TEM images (Fig. 4a–d) and confirmed by HR-SEM (Fig. 4e, f), the resulting particles are relatively monodisperse under these nucleation and growth conditions.
The amount of Au present in the AuNP nanoparticle was quantified using inductively coupled plasma mass spectrometry (ICP-MS). The ICP-MS analysis indicated that the total amount of AuNPs changed from 60.0 to 49.9 and 42.8 mg/L when the synthesis was performed with 1, 2, and 3 mL of the V. oleifera extract, respectively. The adsorption of a larger amount of V. oleifera extract on the nanoparticle surface may limit the increase in the amount of Au in the nanoparticle.
Presence of Phenolic Compounds on the Surface of the AuNPs Synthesized with V. oleifera Ace
To investigate the Raman scattering performance, the signal of the AuNPs coated with organic compounds from V. oleifera was measured (with 633-nm laser excitation at 17 mW for 1 s) (Fig. 8b). To analyze the AuNP-associated biomolecules, two characteristics are extremely important: similarity and intensity. The V. oleifera and AuNPs-V. oleifera spectra were similar, and the spectrum of a molecule in contact with the nanocrystal was enhanced, which indicated that the compounds present in the plant extract functionalized the nanoparticles via irreversible electrostatic interactions. The Raman spectra for the HAuCl4 incubation conditions contained two very strong peaks at 1358 and 1571 cm−1. The position peaks corresponding to the symmetric and asymmetric stretching carboxylic groups (COO−1) are related to the peaks observed at 1358 and 1571 cm−1, respectively . The observed vibrations have also been reported for free and Na feluric acid salt .
The green synthesis of biofunctionalized AuNPs from V. oleifera was simple, environmentally friendly, and economical. Due to the reducing and capping nature of the bioactive compounds present in the aqueous extract of V. oleifera, a cap was formed around the gold ions of the stable biofunctionalized NPs. The presence of the functional group of the bioactive compounds was confirmed by FTIR and Raman spectroscopy. The particle size, quasi-spherical shape, and monodispersity of the AuNPs were determined by TEM, SEM, HRSEM, and XRD analyses. V. oleifera may serve as a source of biofunctionalized NPs for a wide range of in vitro assays. The results of this study are as follows: (i) the synthesis using V. oleifera allows for the preparation of monodisperse AuNPs that are homogenous in size and shape and stable in solution, (ii) the presence of organic compounds that can potentially offer important biological activity for these nanoparticles, and (iii) a new route for the production of bioactive gold nanoparticles.
Our studies provide an important basis for the application of the green synthesis of gold nanoparticles using V. Oleifera.
This work was partially supported by the Brazilian Ministry of Science and Technology (CNPq Grant 483036/2011-0), the Education Ministry (MEC-PROEXT Grant 04/2011), the Ministry of Science and Technology (MCTI/FINEP/CT-INFRA grant PROINFRA 01/2006), and Espírito Santo Research Foundation (FAPES). The authors wish to acknowledge the LABIOM at Universidade Federal do Espírito Santo for providing the equipment and technical support for the UV-vis experiments.
MBA, who was the student responsible for the work, conceived and designed the experiments. OJP, AI, CAS, FDM, and KWJ provided support and performed the synthesis, physical characterization, and electron microscope experiments. NOC, GRCR, and KRR performed the analytical assays and co-wrote the paper. CVG performed cyclic voltammetry. RA measured the zeta potential. PACH and EDC performed the V. oleifera isolation and characterization and co-wrote the paper. SRP analyzed the data. GMCC supervised the project, and all of the authors contributed to data discussions. All of the authors commented on the manuscript. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
- Dreaden EC, Alkilany AM, Huang X, Murphy CJ, El-Sayed MA (2012) The golden age: gold nanoparticles for biomedicine. Chem Soc Rev 41:2740–2779View ArticleGoogle Scholar
- Kelly KL, Coronado E, Zhao LL, Schatz GC (2003) The optical properties of metal nanoparticles: the influence of size, shape and dieletric environment. J Phys Chem B 107:668–677View ArticleGoogle Scholar
- Boruah SK, Boruah PK, Sarma P, Medhi C, Medhi OK (2012) Green synthesis of gold nanoparticles using Camellia sinensis and kinetics of the reaction. Adv Mater Lett 3:481–486View ArticleGoogle Scholar
- Ganesan RM, Prabu HG (2015) Synthesis of gold nanoparticles using herbal Acoruscalamus rhizome extract and coating on cotton fabric for antibacterial and U blockin applications. Arab J Chem. doi:10.1016/j.arabjc.2014.12.017 Google Scholar
- Nie Z, Petukhova A, Kumacheva E (2010) Properties and emerging applications of self-assembled structures made from inorganic nanoparticles. Nat Nanotechnol 5:15–25View ArticleGoogle Scholar
- Khlebtsov NG, Dykman LA (2010) Optical properties and biomedical applications of plasmonic nanoparticles. J Quant Spectrosc Radiat Transf 111:1–35View ArticleGoogle Scholar
- Becheri A, Dürr M, Nostro PL, Baglioni P (2008) Synthesis and characterization of zinc oxide nanoparticles: application to textiles as UV-absorbers. J Nanopart Res 10:679–689View ArticleGoogle Scholar
- Sperling RA, Gil PR, Zhang F, Zanella M, Parak WJ (2008) Biological applications of gold nanoparticles. Chem Soc Rev 37:1896–1908View ArticleGoogle Scholar
- Ghosh P, Han G, De M, Kim CK, Rotello VM (2008) Gold nanoparticles in delivery applications. Adv Drug Deliv Rev 60:1307–1315View ArticleGoogle Scholar
- Dykman L, Khlebtsov N (2012) Gold nanoparticles in biomedical applications: recent advances and perspectives. Chem Soc Rev 41:2256–2282View ArticleGoogle Scholar
- Pissuwan D, Niidome T, Cortie MB (2011) The forthcoming applications of gold nanoparticles in drug and gene delivery systems. J Control Release 149:65–71View ArticleGoogle Scholar
- Khlebtsov N, Bogatyrev V, Dykman L, Khlebtsov B, Staroverov S, Shirokov A, Matora L, Khanadeev V, Pylaev T, Tsyganova N, Terentyuk G (2013) Analytical and theranostic applications of gold nanoparticles and multifunctional nanocomposites. Theranostics 3:167–180View ArticleGoogle Scholar
- Omidfar K, Khorsand F, Azizi MD (2013) New analytical applications of gold nanoparticles as label in antibody based sensors. Biosens Bioelectron 43:336–347View ArticleGoogle Scholar
- Patel J, Němcová L, Maguire P, Graham WG, Mariotti D (2013) Synthesis of surfactant-free electrostatically stabilized gold nanoparticles by plasma-induced liquid chemistry. Nanotechnology 24:1–12View ArticleGoogle Scholar
- Kumar V, Yadav SK (2009) Plant-mediated synthesis of silver and gold nanoparticles and their applications. J Chem Technol Biotechnol 84:151–157View ArticleGoogle Scholar
- Sujitha MV, Kannan S (2013) Green synthesis of gold nanoparticles using Citrus fruits (Citrus limon, Citrus reticulata and Citrus sinensis) aqueous extract and its characterization. Spectrochim Acta A Mol Biomol Spectrosc 102:15–23View ArticleGoogle Scholar
- Elia P, Zach R, Hazan S, Kolusheva S, Porat Z, Zeiri Y (2014) Green synthesis of gold nanoparticles using plant extracts as reducing agents. Int J Nanomedicine 9:4007–4021Google Scholar
- Daizy P (2010) Green synthesis of gold and silver nanoparticles using Hibiscus rosa sinensis. Physica E 42:1417–1424View ArticleGoogle Scholar
- Das RK, Gogoi N, Babu PJ, Sharma P, Mahanta C, Bora U (2012) The synthesis of gold nanoparticles using Amaranthus spinosus leaf extract and study of their optical properties. Adv Mater Phys Chem 2:275–281View ArticleGoogle Scholar
- Gopinath K, Gowri S, Karthika V, Arumugam A (2014) Green synthesis of gold nanoparticles from fruit extract of Terminalia arjuna, for the enhanced seed germination activity of Gloriosa superba. J Nanostruct Chem 4:1–11Google Scholar
- Pal R, Panigrahi S, Bhttacharyya D, Chakraborti AS (2013) Characterization of citrate capped gold nanoparticle-quercetin complex: experimental and quantum chemical approach. J Mol Struct 1046:153–163View ArticleGoogle Scholar
- Katti KK, Kattumuri V, Bhaskaran S, Katti KV, Kannan R (2009) Facile and general method for synthesis of sugar coated gold nanoparticles. Int J Green Nanotechnol Biomed 1:53–59View ArticleGoogle Scholar
- Vadlapudi V, Kaladhar DSVGK (2014) Green synthesis of silver and gold nanoparticles. Middle East J Sci Res 19:834–842Google Scholar
- Kharissova OV, Dias HVR, Kharisov BI, Perez BO, Perez VMJ (2013) The greener synthesis of nanoparticles. Trends Biotechnol 31:240–248View ArticleGoogle Scholar
- Baliano AP, Alves FS, Pereira ACH, Aquije GMFV, Lenz D, Andrande TU, Endringer DC (2015) Centennial knowledge of medicinal plants held in communities of Espírito Santo, Brazil. Ethnobot Res Appl 14:155–162Google Scholar
- Rao KJ, Paria S (2014) Green synthesis of gold nanoparticles using aqueous Aegle marmelos leaf extract and their application for thiamine detection. RSC Adv 4:28645–28652View ArticleGoogle Scholar
- Isaac RSR, Sakthivel G, Murthy C (2013) Green synthesis of gold and silver nanoparticles using Averrhoa bilimbi fruit extract. J Nanotechnol 1:1–6View ArticleGoogle Scholar
- Li K, Ma C, Liu Y, Zhao F, Tong S (2000) Rayleigh light scattering and its applications to biochemical analysis. Chin Sci Bull 45:386–387View ArticleGoogle Scholar
- Kuznetsova YV, Rempela AA (2015) Size and zeta potential of CdS nanoparticles in stable aqueous solution of EDTA and NaCl. Inorg Mater 51:215–219View ArticleGoogle Scholar
- Stuart BH (2004) Infrared spectroscopy: fundamentals and applications. John Wiley & Sons, Chichester, p 244View ArticleGoogle Scholar
- Stuart BH (1997) Biological applications of infrared spectroscopy, ACOL series. Wiley, Chichester, p 204Google Scholar
- Albuquerque MLS, Guedes I, Alcântara PJ, Moreira SGC (2003) Infrared absorption spectra of Buriti (Mauritia flexuosa L.) oil. Vib Spectrosc 33:127–131View ArticleGoogle Scholar
- Tavares SA, Pereira J, Guerreiro MC, Pimenta CJ, Pereira L, Missagia SV (2011) Physical and chemical characteristics of the mucilage of lyophilized yam. Ciênc Agrotec 35:973–979View ArticleGoogle Scholar
- Costa MNFS, Muniz MAP, Negrao CAB, Costa CEF, Lamarao MLN, Morais L, Silva-Junior JOC, Costa RMR (2014) Characterization of Pentaclethra macroloba oil. J Therm Anal Calorim 115:2269–2275View ArticleGoogle Scholar
- Lopes WA, Fascio M (2004) Flow chart for infrared spectra interpretation of organic compounds. Quim Nova 27:670–673View ArticleGoogle Scholar
- Pu W, Dongmei W, Zhou D (2015) Structural characterization and evaluation of the antioxidant activity of phenolic compounds from Astragalus taipaishanensis and their structure-activity relationship. Sci Rep 5:1–11Google Scholar
- Argolo ACC, SantAna AEG, Coelho LCBB (2004) Antioxidant activity of leaf extracts from Bauhinia monandra. Bioresour Technol 95:229–233View ArticleGoogle Scholar
- Mak JSW, Rutledge SA, Abu-Ghazalah RM, Eftekhari F, Irizar TNCM, Zheng G, Helmy AS (2013) Recent developments in optofluidic-assisted Raman spectroscopy. Prog Quantum Electron 37:1–50View ArticleGoogle Scholar
- Khvan YAM, Kristallovich EL, Abduazimov KA (2001) Complexation of caffeic and ferulic acids by transition-metal ions. Chem Nat Compd 37:72–75View ArticleGoogle Scholar