Journal of Applied Science and Agriculture, 9(9) July 2014, Pages: 176-182
AENSI Journals
Journal of Applied Science and Agriculture
ISSN 1816-9112
Journal home page: www.aensiweb.com/JASA
Synthesis of PVP-Capped Silver Nanoprism with Tunable Localized Surface Plasmon
Resonance
1
1
2
Ebrahim Heidari, 2Javad Khodaveisi and 2Razeih Dashti
Department of Sciences, Bushehr Branch, Islamic Azad University, Bushehr, Iran.
Young Researchers and Elite Club, Islamic Azad University, Bushehr Branch, Bushehr, Iran.
ARTICLE INFO
Article history:
Received 21 April 2014
Received in revised form 23
May 2014
Accepted 13 June 2014
Available online 10 August 2014
Keywords:
Silver nanoprism, Localized surface
plasmon resonance, UV–vis
spectroscopy, Polyvinylpyrrolidone
Supported Hydrogen Peroxide (PVPH2O2), ethanol
ABSTRACT
Polyvinylpyrrolidone supported hydrogen peroxide (PVP-H2O2) was used as a capping
agent to directly synthesize silver nanoprism. The localized surface plasmon resonance
(LSPR) peak of the silver nanoprism can be tuned from 420nm to 700nm by decreasing
the PVP-H2O2 concentration. The synthesis process of the silver nanoprism was
investigated by UV–vis spectroscopy and transmission electron microscopy (TEM). It
was found that the concentration of modified capping agent important role in the
morphology control of produced silver nanoprism. As one of the applications of this
nanoprism, they were used as localized surface plasmon resonance sensor for ethanol as
a spectrophotpmetric probe to evaluate the enhancement ability of the triangular silver
nanoprism.
© 2014 AENSI Publisher All rights reserved.
To Cite This Article: Ebrahim Heidari, Javad Khodaveisi and Razeih Dashti., Synthesis of PVP-Capped Silver Nanoprism with Tunable
Localized Surface Plasmon Resonance. J. Appl. Sci. & Agric., 9(9): 176-182, 2014
INTRODUCTION
Silver nanoparticles have traditional much focus recently due to their unique optical properties and
significant application for synthesis of chemical sensor. Silver nanoparticles are also shows potential for
application as active substrates for surface-enhanced Raman scattering, near-field optical sensor and biomedical
imaging (Sonnichsen, C., 2005; Eustis, S., M.A. El-Sayed, 2006; Love, J.C., 2005; Cheng, D.M., Q.H. Xu,
2007; Graham, D., 2006; Ma, Z.F., 2009; Aslan, K., 2005; Chen, Y., 2007; Xue, C., 2007). For silver
nanoprism, while there has been small information with regards to their application (Shi, W.T., Z.F. Ma, 2010),
a number of shape-controlled synthesis techniques have been developed, including photo or thermally induced
transformation, microemulsion and chemical reduction method (Jin, R.C., 2001; Sun, Y., 2003; Song, J., 2008;
Cao, Z.W., 2008; Washio, I., 2006; Xiong, Y., 2006). In these synthesis techniques, bis(p-sulfonatophenyll)
phenylphosphine dehydrate dipotassium, trisodium citrate (TSC), cetyltrimethylammonium bromide, poly(vinyl
pyrrolidone) often serve as capping agent to synthesize silver nanoprism.
Recently, several studies have been published on the use of the LSPR spectrum technique for the detection
of Chemical and biological compund (Haes, A.J., R.P. van Duyne, 2002; Riboh, J.C., 2003; Yonzon, C.R.,
2004; Haes, A.J., 2005; Dahlin, A., 2005). In addition there are few reports on LSPR sensing applications in the
liquid phase for the detection of organophosphorous pesticides (Lin, T.J., 2006), hydrogen peroxide (Endo, T.,
2008), and ammonia (Dubas, S.T., V. Pimpan, 2008). In terms of gas phase detection, also some papers in
inorganic gases sensing (Hu, J.L., 2009; Bingham, J.M., 2010; Kreno, L.E., 2010; Cheng, C.S., 2007; Chen,
Y.Q., C.J. Lu, 2009) were carried out to discover the LSPR spectra response to a series of gases such as octane,
pentanol. Vaskevich and coworkers (Karakouz, T., 2008) found that a polymer coated gold island showed
selective gas sensing characteristics by investigating the extinction spectrum response to several vapors
qualitatively, without obtaining the exact sensing sensitivity and detection limits.
Herein, Polyvinylpyrrolidone supported hydrogen peroxide (PVP-H2O2) was used as a capping agent to
directly synthesize silver nanoprism. The localized surface plasmon resonance (LSPR) peak of the silver
nanoprism can be tuned from 420nm to 700nm by decreasing the PVP-H2O2 concentration. The synthesis
process of the silver nanoprism was investigated by UV–vis spectroscopy and transmission electron microscopy
(TEM). It was found that the concentration of modified capping agent important role in the morphology control
of produced silver nanoprism. As one of the applications of this nanoprism, they were used as localized surface
Corresponding Author: Ebrahim Heidari, Department of Sciences, Bushehr Branch, Islamic Azad University, Bushehr,
Iran
177
Ebrahim Heidari et al, 2014
Journal of Applied Science and Agriculture, 9(9) July 2014, Pages: 176-182
plasmon resonance sensor for ethanol as a spectrophotpmetric probe to evaluate the enhancement ability of the
triangular silver nanoprism.
Experimental:
Apparatus:
The UV–Vis absorbance spectrum was recorded on an Avantes photodiode array spectrophotometer model
Ava- Spec-2048 with 1.0 cm glass cell. Measurements of pH were made with a Denver Instrument Model 270
pH meter equipped with a Metrohm glass electrode. The size and shape of the Silver nanoprism were
characterized by transmission electron microscopy (TEM) using a Zeiss transmission electron microscope
operated at an accelerating voltage of 80 kV.
Materials:
All chemicals used were of analytical reagent grade and the solutions were prepared with deionized water.
Polyvinylpyrrolidone K-30 (average Mw. 40,000), hydrogen peroxide, ascorbic acid and silver nitrate were
purchased from Merck (Darmstadt, Germany) and Fluka. All other common laboratory chemicals were of the
best grade available and were used without further purification. All solutions were used within 1 h after
preparation, and the experiments were performed at ambient temperature (25 ±2 ◦C). Solution of ascorbic
acidand hydrogen peroxide were prepared daily by dissolving the reagents in deionized water.
Synthesis of Polyvinylpyrrolidone Supported Hydrogen Peroxide (PVP-H2O2):
PVP-H2O2 was synthesized by the method reported in literature [29]. In summary, a solution of 30% H 2O2
(6 mL) at 0 ℃ was added to PVP K-30 (2 g) while the solution was quietly stirred. After 1 h, the resulting
solution was poured on a glass plate to dry overnight at room temperature. Then, the dried solid was powdered
in a mortar. The capacity of the reagent was determined to be 7.5 mmol of H2O2 per gram of the solid reagent.
The reagent stored in the refrigerator for more than a few months with no loss of weight or activity.
Silver nanoparticles synthesis:
A silver nanoparticles solution was prepared by the reduction reaction of silver nitrate by ascorbic acid. In a
typical synthesis of nanoprism silver nitrate, polyvinylpyrrolidone Supported Hydrogen Peroxide (PVP-H2O2)
and trisodium citrate were added to a 200 ml glass beaker and mixed to give a homogenous solution. Then
ascorbic acid was injected into the solution at ambient temperature. In the case of silver nanosphere synthesis,
we use of unmodified polyvinylpyrrolidone as a stabilizer and ascorbic acid as a reductant agent. For synthesis
of other solution of nanoparticles with tunable λmax. We used a solution of capping agent by constant PVP
concentration but with varying ratios of PVP-H2O2 to PVP.
Coating:
Colloidal solution of nanoparticles then was deposit onto normal microscope glass plates by spin coating at
speeds in the range of 1000–3000 rpm for 1 min. Then thermal processing of modified PVP/Ag nanoparticle
composite films at temperatures of 300 ºC for 1 min. The spin coating speed determines the thickness of
PVP/Ag composite layer and therefore the density of nanoparticles per unit area. The thermal processing is used
to dry the solvent and promote adherence of the nanoparticles to the glass substrate.
Detection of ethanol:
The Schematic presentation of experimental setup is shown in Figure 1. A light beam radiated by a halogen
lamp was propagated during an optical fiber to illuminate the sensor. On the other side of the sensor, it was
collected by another fiber. The LSPR spectra were measured at room temperature (20 °C) by using a UV-Vis
Spectrometer. The spectrometer was operated at a wavelength resolution of 1 nm in our experiment, and the
extinction can be evaluated by:
𝐸 𝜆 = − log10 (
𝑆 𝜆 −𝐷 𝜆
𝑅 𝜆 −𝐷 𝜆
)
(1)
where S(λ), D(λ) and R(λ) denote the sample intensity, the dark intensity, and the reference intensity at the
wavelength of λ, respectively. A gas cell was used in this research to supply a platform where the test vapor was
adsorbed on the transducer and the vapor concentration was transmitted into the optical signal.
178
Ebrahim Heidari et al, 2014
Journal of Applied Science and Agriculture, 9(9) July 2014, Pages: 176-182
Fig. 1: Schematic presentation of experimental setup.
The test vapor of a defined concentration was prepared by injecting a specific volume of saturated vapor
into the gas cell, where the saturated vapor was produced by stewing a certain amount of the corresponding
matter of liquid phase in a big sealed container for several hours. The injection volume in experiment was
defined as:
𝐶
𝑉𝑖 = 𝑑 𝑉𝑟
(2)
𝐶𝑠
where Cd, Cs and Vr refer to the test vapor concentration, the saturated vapor concentration and the volume of
gas cell, respectively.
RESULTS AND DISCUSSION
Synthesis of a nanoparticles colloid with tunable λmax:
The systems in this study consist of an aqueous AgNO3 solution that includes polyvinylpyrrolidone (PVP)
in modified and unmodified type, as stabilizer, at an ambient temperature. Sodium borohydrideact is effective
reducing agents for reduction of silver metal salt (Ag +) to the silver nanoparticles without added any seeds
(Figure 2). In the absence of hydrogen peroxide as modifier in stabilizer agent the result of reaction is silver
nanosphere with yellow color, when modified stabilizer is used in the synthesis the result is formation of silver
nanoprism.
Fig. 2: Schematic Formation of silver nanosphere and nanoprism.
In our research, a study was focused on the effect of PVP-H2O2 concentration on the synthesis procedure of
nanoprism. We used a solution of capping agent by constant PVP concentration but with varying ratios of PVPH2O2 to PVP. The Ratio PVP-H2O2 to PVP was altered from 100 to zero, while keep the other experimental
conditions fixed. After some time, the mixed solution appeared with different colors, which varied with different
179
Ebrahim Heidari et al, 2014
Journal of Applied Science and Agriculture, 9(9) July 2014, Pages: 176-182
percentage of PVP-H2O2, namely, green for % PVP-H2O2 = 100, and then deepened when % PVP-H2O2 was
increased from 0 to 100%, yellow for % PVP-H2O2 = 0 and blue for % PVP-H2O2 = 60, respectively, as shown
in Fig. 2. The color change occurred within 10min.
1.4
A
B
C
1.2
Absorbance
1
0.8
0.6
0.4
0.2
0
300
400
500
600
Wavelength (nm)
700
800
Fig. 3: UV-Vis spectrum of silver nanosphere have single peak at 410 nm and silver nanoprisms have three
peaks approximately 700–620 nm, 490–540nm and 370-390 nm.
LSPR peak has been shown to be a good indicator of general nanoprism structural design. So, the UV–vis
spectrum of these species provides a fast estimate of the nanoprism formed. As shown in Fig. 3, each spectrum
of the as-prepared colloids exhibits three LSPR bands located at approximately 700–620 nm, 490–540nm and
370-390 nm, which are approved to the in-plane dipole, the in-plane quadrupole and the out-of plane quadrupole
resonance of the silver nanoprism, respectively. From the spectrum of b and c in Fig. 3, the LSPR band of the
nanoprism presents a notable red-shift from 620nm to 700nm by simply varying the % PVP-H2O2 from 40 to
100%. In addition the morphological study of the nanoprism by TEM clearly reveals that the presence of
Polyvinylpyrrolidone Supported Hydrogen Peroxide (PVP-H2O2) during the reduction of silver ions results in
the growth of triangular silver crystallites (Fig. 4).
Fig. 4: TEM images of silver nanoprisms.
180
Ebrahim Heidari et al, 2014
Journal of Applied Science and Agriculture, 9(9) July 2014, Pages: 176-182
Sensor for ethanol:
According to the test results for the sensor exposed to ethanol vapor of different concentrations presented in
Figure 5, the peak wavelength of the spectrum shifts from 701 nm to 714 nm gradually when the ethanol
concentration varies from 0 mg/L (in air) to 140 mg/L.
0.9
Absorbance
0.85
0.8
0.75
0.7
680
690
700
710
720
730
740
750
Wavelength (nm)
Fig. 5: LSPR spectra response to different ethanol vapor concentrations.
The extinction spectra peak wavelength shift (0 mg/L as the base point) as a function of ethanol vapor
concentration is plotted in Figure 6. As the concentration increases from 0 mg/L to 140 mg/L, in increment of 20
mg/L, the peak shift amount increases gradually, suggesting a linear relationship.
16
14
y = 0.101x + 0.211
R² = 0.997
12
Peak shift (nm)
10
8
6
4
2
0
0
50
100
150
Concentration (mg/L)
Fig. 6: Response sensitivity of LSPR spectrum calibrated with eight different ethanol vapor concentrations.
Hence, we define “vapor sensor sensitivity” m to directly evaluate the sensing performance of metal
nanostructures based volatile organic vapor sensors:
𝑚=
∆𝜆 𝑝 𝑛𝑚
∆𝐶𝑑 𝑚𝑔 /𝐿
(3)
where Δλp and ΔCd denote the peak wavelength shift in a certain vapor concentration relative to that in air and
the corresponding concentration change. For the ethanol vapor test, the sensitivity is approximately 0.1 nm/mg
181
Ebrahim Heidari et al, 2014
Journal of Applied Science and Agriculture, 9(9) July 2014, Pages: 176-182
L−1. The detection limit, determined by the sensor sensitivity as well as the operational resolution of the applied
detector, is approximately 11 mg/L.
Conclusion:
In summary, silver nanoprism were successfully prepared using PVP-H2O2 as a capping agent. The LSPR
peak of nanoprism can be tuned from 420nm to 700nm with the decrease of %PVP-H2O2 from 0 to 100. A red
shift extinction spectrum can be observed as the concentration of the ethanol vapors increases. The sensitivity,
defined as the peak wavelength shift per vapor concentration change in ambient conditions, is approximately 0.1
nm/mg L−1 for ethanol. The detection limit, determined by the sensitivity of the sensor and the wavelength
resolution of the applied spectrometer, is approximately 11 mg/L for ethanol in our experiments. Besides, the
triangular nanoprisms based ethanol vapor sensor has a relatively fast response time (~4 s) and a good sensing
stability and reversibility. This study indicates the great potential in practical applications in detection of ethanol
vapors for the LSPR sensor.
ACKNOWLEDGMENTS
One of the authors (E. H.) acknowledges that this research has been financially supported by the office of
vice chancellor for research of Islamic Azad University, Bushehr Branch.
REFERENCES
Aslan, K., J.R. Lakowicz, C.D. Geddes, 2005. Rapid deposition of triangular silver nanoplates on planar
surfaces: application to metal-enhanced fluorescence, J. Phys. Chem., B 109: 6247-6251.
Bingham, J.M., J.N. Anker, L.E. Kreno, R.P. Van Duyne, 2010. Gas Sensing with High ResolutionLocalized Surface Plasmon Resonance Spectroscopy, J. Am. Chem. Soc., 132: 17358-17359.
Cao, Z.W., H.B. Fu, L.T. Kang, 2008. Rapid room-temperature synthesis of silver nanoplates with tunable
in-plane surface plasmon resonance from visible to near-IR, J. Mater. Chem., 18: 2673–2678.
Chen, Y., C.G. Wang, Z.F. Ma, Z.M. Su, 2007. Controllable colors and shapes of silver nanostructures
based on pH: application to SERS, Nanotechnology, 18: 325602.
Chen, Y.Q., C.J. Lu, 2009. Surface modification on silver nanoparticles for enhancing vapor selectivity of
localized surface plasmon resonance sensors, Sens. Actuat. B: Chem., 135: 492-498.
Cheng, C.S., Y.Q. Chen, C.J. Lu, 2007. Organic vapour sensing using localized surface plasmon resonance
spectrum of metallic nanoparticles self assemble monolayer, Talanta, 73: 358-365.
Cheng, D.M., Q.H. Xu, 2007. Separation distance dependent fluorescence enhancement of fluorescein
isothiocyanate by silver nanoparticles, Chem. Commun., 3: 248-250.
Dahlin, A., M. Zach, T. Rindzevicius, M. Kall, D.S. Sutherland, F. Hook, 2005. Localized surface plasmon
resonance sensing of lipid-membrane-mediated biorecognition events, J. Am. Chem. Soc., 127: 5043-5048.
Dubas, S.T., V. Pimpan, 2008. Green synthesis of silver nanoparticles for ammonia sensing, Talanta, 76:
29-33.
Endo, T., Y. Yanagida, T. Hatsuzawa, 2008. Quantitative determination of hydrogen peroxide using
polymer coated Ag nanoparticles, Measurement, 41: 1045-1053.
Eustis, S., M.A. El-Sayed, 2006. Why gold nanoparticles are more precious than pretty gold: noble metal
surface plasmon resonance and its enhancement of the radiative and nonradiative properties of nanocrystals of
different shapes, Chem. Soc.Rev., 35: 209-217.
Graham, D., K. Faulds, W.E. Smith, 2006. Biosensing using silver nanoparticles and surface enhanced
resonance raman scattering, Chem. Commun., 42: 4363-4371.
Haes, A.J., L. Chang, W.L. Klein, R.P. van Duyne, 2005. Detection of a Biomarker for Alzheimer’s disease
from Synthetic and Clinical Samples using a Nanoscale Optical Biosensor, J. Am. Chem. Soc., 127: 2264-2271.
Haes, A.J., R.P. van Duyne, 2002. A Nanoscale Optical Biosensor: Sensitivity and Selectivity of an
Approach Based on the Localized Surface Plasmon Resonance Spectroscopy of Triangular Silver
Nanoparticles, J. Am. Chem. Soc., 124: 10596-10604.
Hu, J.L., L. Wang, W.P. Cai, Y. Li, H.B. Zeng, L.Q. Zhao, P.S. Liu, 2009. Smart and reversible surface
plasmon resonance responses to various atmospheres for silver nanoparticles loaded in mesoporous SiO 2, J.
Phys. Chem. C, 113: 19039-19045.
Jin, R.C., Y.W. Cao, C.A. Mirkin, K.L. Kelly, G.C. Schatz, J.G. Zheng, 2001. Photoinduced conver- sion of
silver nanospheres to nanoprisms, Science, 294: 1901-1903.
Karakouz, T., A. Vaskevich, I. Rubinstein, 2008. Structural and Optical Properties of Evaporated Gold
Island Films , J. Phys. Chem. B, 112: 14530-14538.
Kreno, L.E., J.T. Hupp, R.P. van Duyne, 2010. Metal-Organic Framework Thin Film for Enhanced
Localized Surface Plasmon Resonance Gas Sensing, Anal. Chem., 82: 8042-8046.
182
Ebrahim Heidari et al, 2014
Journal of Applied Science and Agriculture, 9(9) July 2014, Pages: 176-182
Lin, T.J., K.T. Huang, C.Y. Liu, 2006. Determination of organophosphorous pesticides by a novel
biosensor based on localized surface plasmon resonance, Biosens. Bioelectron, 22: 513-518.
Love, J.C., L.A. Estroff, J.K. Kriebel, 2005. Self-assembled monolayers of thiolates on metals as a form of
nanotechnology, Chem. Rev. 105: 1103-1169.
Ma, W.Y., H. Yang, J.P. Hilton, Q. Lin, J.Y. Liu, L.X. Huang, J. Yao, 2010. A numerical investigation of
the effect of vertex geometry on localized surface plasmon resonance of nanostructures, Opt. Express, 18: 843853.
Ma, W.Y., J. Yao, H. Yang, J.Y. Liu, F. Li, J.P. Hilton, Q. Lin, 2009. Effects of vertex truncation of
polyhedral nanostructures on localized surface plasmon resonance, Opt. Express, 17: 14967-14976.
Ma, Z.F., G.L. Si, Y.M. Chu, Y. Chen, 2009. Research advances on triangular silver nanoprisms, Prog.
Chem., 21: 1847-1856.
Riboh, J.C., A.J. Haes, A.D. McFarland, C.R. Yonzon, R.P. van Duyne, 2003. A Nanoscale Optical
Biosensor: Real Time Immunoassay and Nanoparticle Adhesion, J. Phys. Chem. B, 107: 1772-1780.
Shi, W.T., Z.F. Ma, 2010. Amperometric glucose biosensor based on a triangular silver
nanoprisms/chitosan composite film as immobilization matrix, Biosens. Bioelectron, 26: 1098-1103.
Song, J., Y. Chu, Y. Liu, 2008. Chem. Commun. Room temperature controllable fabrication of silver
nanoplates reduced by aniline, 10: 1223-1225.
Sonnichsen, C., B.M. Reinhard, J. Liphardt, A.P. Alivisatos, 2005. A molecular ruler based on plasmon
coupling of single gold and silver nanoparticles, Nat. Biotechnol., 23: 741-745.
Sun, Y., B. Mayers, Y. Xia, 2003. Transformation of silver nanospheres into nanobelts and triangular
nanoplates through a thermal process, Nano Lett., 3: 675-679.
Washio, I., Y. Xiong, Y. Yin, Y.N. Xia, 2006. Reduction by the End Groups of Poly(vinyl pyrrolidone): A
New and Versatile Route to the Kinetically Controlled Synthesis of Ag Triangular Nanoplates, Adv. Mater, 18:
1745-1749.
Xiong, Y., I. Washio, J. Chen, H.G. Cai, Z.Y. Li, Y.N. Xia, 2006. Poly(vinyl pyrrolidone): A
DualFunctional Reductant and Stabilizer for the Facile Synthesis of Noble Metal Nanoplates inAqueous
Solutions, Langmuir, 22: 8563-8570.
Xue, C., X. Chen, S.J. Hurst, C.A. Mirkin, 2007. Self-assembled monolayer mediated silica coating of
silver nanoprisms, Adv. Mater, 19: 4071-4074.
Yonzon, C.R., E. Jioung, S. Zou, G.C. Schatz, M. Mrksich, R.P. Van Duyne, 2004. A Comparative
Analysis of Localized and Propagating Surface Plasmon Resonance Sensors: The Binding of Concanavalin A to
a Monosaccharide Functionalized Self-Assembled Monolayer, J. Am. Chem. Soc., 126: 12669-12676.