Thermal diffusivity measurement for urchin-like gold nanofluids with different solvents, sizes and concentrations/shapes
© López-Muñoz et al.; licensee Springer. 2012
Received: 12 November 2012
Accepted: 24 November 2012
Published: 6 December 2012
The thermal properties of nanofluids are an especially interesting research topic because of the variety of potential applications, which range from bio-utilities to next-generation heat-transfer fluids. In this study, photopyroelectric calorimetry for measuring the thermal diffusivity of urchin-like colloidal gold nanofluids as a function of particle size, concentration and shape in water, ethanol and ethylene glycol is reported. Urchin-like gold nanoparticles were synthesised in the presence of hydroquinone through seed-mediated growth with homogeneous shape and size ranging from 55 to 115 nm. The optical response, size and morphology of these nanoparticles were characterised using UV-visible spectroscopy and transmission electron microscopy. The thermal diffusivity of these nanofluids decreased as the size of the nanoparticles increased, and the enhancement depended on the thermal diffusivity of the solvent. The opposite effect (increase in thermal diffusivity) was observed when the nanoparticle concentration was increased. These effects were more evident for urchin-like gold nanofluids than for the corresponding spherical gold nanofluids.
KeywordsUrchin-like gold nanoparticles Nanofluids Photopyroelectric Thermal diffusivity
Currently, thermal properties of nanofluids, i.e. mixtures of nanomaterials suspended in an organic or inorganic base fluid, are intriguing because of their various uses, which range from bio-applications to the next generation of heat-transfer fluids. For example, gold nanofluids are a promising material for bio-applications because of their biocompatibility and thermo-optical properties. In particular, urchin-like gold fluids have a higher surface area that endows them with specific catalytic and thermo-optical qualities . The surface plasmon resonance of urchin-like gold nanofluids can be tuned to the near-infrared region by increasing the particle size, which makes the particles potentially effective in photothermal therapy and as contrast agents for diagnosis . In addition, local electromagnetic field enhancement at the tips of branched particles and thermal conductivity enhancement make these materials a candidate for application in electromagnetic hyperthermia therapy [3, 4]. Thermal studies of nanofluids have mainly focused on thermal conductivity measurements, but recently, other techniques have been developed for thermal diffusivity measurements in nanofluids, such as the hot-wire technique and thermal lens spectrometry [5–7].
In the present study, the aqueous synthesis of urchin-like gold nanoparticles in the presence of hydroquinone through a seed-mediated growth process is presented. The thermal diffusivity in urchin-like gold nanofluids as a function of particle size (55 to 115 nm) and concentration in different solvents was investigated by photopyroelectric calorimetry. A comparative study of thermal diffusivity in urchin-like and spherical gold nanofluids with approximately equal particle sizes as a function of concentration is also reported. These results will open new horizons for thermal studies of nanofluids for bio-applications and heat-transfer applications.
Hydroquinone synthesis of urchin-like gold nanoparticles
Urchin-like gold nanoparticles are commonly synthesised through a self-seeding growth process, where larger particles grow through the deposition of smaller seeds that form from the epitaxial deposition of atoms. The reduction of gold chloride on the nanoparticle seeds (gold nanoparticles, <20 nm) paired with hydroquinone as a selective reducing agent improves the homogeneous size and shape distribution of the urchin-like particles through physicochemical effects [8, 9].
Gold nanoparticle seeds were synthesised by sodium citrate reduction. For this process, a solution of gold chloride is brought to boil, whereupon a solution of sodium citrate is immediately added. The solution is then removed from the heat source once nanoparticle maturation is completed, as indicated by the colour transition.
Urchin-like gold nanoparticles were synthesised by hydroquinone method using consistent concentrations of gold chloride, sodium citrate and hydroquinone; however, the number of seeds gradually decreased, which resulted in the formation of larger urchin-like gold nanoparticles. Nanofluids with varying particle size were centrifuged at 6,000 rpm for 30 min and re-dispersed in high-performance liquid chromatography (HPLC) water, ethanol and ethylene glycol (EG) at a final concentration of 0.1 mg/ml.
To provide nanofluids with different shapes and concentrations, stock solutions of urchin-like gold nanoparticles and spherical gold nanofluids synthesised by hydroquinone method [9, 10] were centrifuged at 6,000 rpm for 30 min. The concentrated solutions were re-dispersed in HPLC water, ethanol and ethylene glycol to obtain different nanoparticle concentrations.
All chemicals used were of analytical grade as obtained from Sigma-Aldrich Corporation (St. Louis, MO, USA) and were used as received; HPLC water was used for the synthesis of all the urchin-like and spherical gold nanoparticles.
Basic photopyroelectric theoretical scheme
from which the thermal diffusivity of the sample can be determined.
The pyroelectric signal was recorded as a function of the sample thickness by measuring 20 experimental points from a relative sample thickness l 0 , at 10-μm intervals using a micro-linear stage (model T-LSM025A; Zaber Technologies, Inc., Vancouver, Canada). Linear fits were performed for the pyroelectric phase to obtain the B parameter, as defined in the ‘Basic photopyroelectric theoretical scheme’ section, from which the thermal diffusivity of the sample was obtained by means of the relationship αs = π/B2. Measurements were performed at room temperature, or 22 ± 2°C.
Results and discussion
Thermal diffusivity measurement
Thermal diffusivity of urchin-like gold nanofluids for different nanoparticle diameters and solvents
Particle size (nm)
Thermal diffusivity of urchin-like gold nanofluids at different nanoparticle concentrations and in different solvents
Thermal diffusivity of spherical gold nanofluids at different nanoparticle concentrations and in different solvents
The present study investigated the effects of concentration, size and solvent on the thermal diffusivity of urchin-like gold nanofluids prepared by hydroquinone method through seed-mediated growth. The low size dispersion of urchin-like gold nanoparticles synthesised by hydroquinone method is advantageous when compared with single-step methods that are less capable of continuously controlling the diameters of branched particles; such control is critical as it is directly related to the tunable surface plasmon resonance of the urchin-like nanoparticles. The thermal diffusivity ratio changed inversely with nanoparticle size, which varied from 55 to 115 nm for urchin-like gold nanofluids. The thermal diffusivity ratio has been found to increase with nanoparticle concentration and was thus investigated within the range of 1 to 0.2 mg/ml for the gold nanofluids. The thermal diffusivity ratio increased inversely with the thermal diffusivity of the nanofluid solvent. Moreover, the particle shape was found to have an effect on the thermal diffusivity of nanofluids. Experimental data for the thermal diffusivity ratio as a function of concentration and size for gold nanofluids depict similar behaviours in the enhancement ratio when compared with the thermal diffusivity using other techniques reported in the literature with high accuracy. Because of the small amount of sample required (600 μl) and the possibility to provide additional information such as the thermal and optical parameters of the sample with the developed sensor, photopyroelectric calorimetry is a promising alternative to classical techniques for measuring the thermal diffusivity of nanofluids.
High-performance liquid chromatography
Transmission electron microscopy
The authors acknowledge Zaber Technologies, Inc. for providing a micro-linear stage and Química Aromática SA, COFAA-IPN and CONACyT for the partial support of this work.
- Wang W, Pang Y, Yan J, Wang G, Suo H, Zhao C, Xing S: Facile synthesis of hollow urchin-like gold nanoparticles and their catalytic activity. Gold Bull 2012, 45: 91. 10.1007/s13404-012-0052-yView ArticleGoogle Scholar
- Liang-Chien C, Jing-Hong H, Hao MC, Tsung-Ching L, Kuang-Yu Y, Ru-Shi L, Hsiao M, Chung-Hsuan C, Li-Jane H, Din PT: Seedless, silver-induced synthesis of star-shaped gold/silver bimetallic nanoparticles as high efficiency photothermal therapy reagent. J Mater Chem 2012, 22: 2244. 10.1039/c1jm13937aView ArticleGoogle Scholar
- Yuan H, Khoury CG, Hwang H, Wilson CM, Grant GA, Vo-Dinh T: Gold nanostars: surfactant-free synthesis, 3D modelling, and two-photon photoluminescence imaging. Nanotechnology 2012, 23(7):075102. 10.1088/0957-4484/23/7/075102View ArticleGoogle Scholar
- Moran CH, Wainerdi SM, Cherukuri TK, Kittrell C, Wiley BJ, Nicholas NW, Curley SA, Kanzius JS, Cherukuri P: Size-dependent joule heating of gold nanoparticles using capacitively coupled radiofrequency fields. Nano Research 2009, 2: 400. 10.1007/s12274-009-9048-1View ArticleGoogle Scholar
- Jiménez-Pérez JL, Cruz-Orea A, Sánchez-Ramírez JF, Sánchez-Sinencio F, Martínez-Pérez L, López Muñoz GA: Thermal characterization of nanofluids with different solvents. Int J Thermophys 2009, 23: 042002.Google Scholar
- Jiménez Pérez JL, Gutierrez Fuentes R, Sanchez Ramirez JF, Cruz-Orea A: Study of gold nanoparticles effect on thermal diffusivity of nanofluids based on various solvents by using thermal lens spectroscopy. Eur Phys J Special Topics 2008, 153: 159. 10.1140/epjst/e2008-00417-5View ArticleGoogle Scholar
- Zhang X, Gu H, Fujii M: Effective thermal conductivity and thermal diffusivity of nanofluids containing spherical and cylindrical nanoparticles. J Appl Phys 2006, 100: 044325. 10.1063/1.2259789View ArticleGoogle Scholar
- Li J, Wu J, Zhang X, Liu Y, Zhou D, Sun H, Zhang H, Yang B: Controllable synthesis of stable urchin-like gold nanoparticles using hydroquinone to tune the reactivity of gold chloride. J Phys Chem C 2011, 115: 3630.View ArticleGoogle Scholar
- Perrault SD, Chan WC: Synthesis and surface modification of highly monodispersed, spherical gold nanoparticles of 50–200 nm. J Am Chem Soc 2009, 131: 17042. 10.1021/ja907069uView ArticleGoogle Scholar
- López-Muñoz GA, Pescador-Rojas JA, Ortega J, Santoyo J, Balderas-López JA: Thermal diffusivity measurement of spherical gold nanofluids of different sizes/concentrations. Nanoscale Res Lett 2012, 7(1):423. 10.1186/1556-276X-7-423View ArticleGoogle Scholar
- Balderas-López JA, Mandelis A, Garcia JA: Thermal-wave resonator cavity design and measurements of the thermal diffusivity of liquids. Rev Sci Instrum 2000, 71: 2933. 10.1063/1.1150713View ArticleGoogle Scholar
- Haiss W, Thanh NT, Aveyard J, Fernig DG: Determination of size and concentration of gold nanoparticles from UV-vis spectra. Anal Chem 2007, 79: 4215. 10.1021/ac0702084View ArticleGoogle Scholar
- Amendola V, Meneghetti M: Size evaluation of gold nanoparticles by UV-vis spectroscopy. J Phys Chem 2009, 113: 4277.Google Scholar
- Murshed SM, Leong KC, Yang C: Determination of the effective thermal diffusivity of nanofluids by the double hot-wire technique. J Phys D: Appl Phys 2006, 39: 5316. 10.1088/0022-3727/39/24/033View ArticleGoogle Scholar
- Ali FM, Yunus WM: Study of the effect of volume fraction concentration and particle materials on thermal conductivity and thermal diffusivity of nanofluids. Jpn J Appl Phys 2011, 50: 085201. 10.1143/JJAP.50.085201View ArticleGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.