Heating Of Gold Nanoparticles Research Articles

Heating of nanoparticles and their environment by laser radiation and applications

This review considers the fundamental dynamic processes involved in the laser heating of metal nanoparticles and their subsequent cooling. Of particular interest are the absorption of laser energy by nanoparticles, the heating of a single nanoparticle or an ensemble thereof, and the dissipation of the energy of nanoparticles due to heat exchange with the environment. The goal is to consider the dependences and values of the temperatures of the nanoparticles and the environment, their time scales, and other parameters that describe these processes. Experimental results and analytical studies on the heating of single metal nanoparticles by laser pulses are discussed, including the laser thresholds for initiating subsequent photothermal processes, how temperature influences the optical properties, and the heating of gold nanoparticles by laser pulses. Experimental studies of the heating of an ensemble of nanoparticles and the results of an analytical study of the heating of an ensemble of nanoparticles and the environment by laser radiation are considered. Nanothermometry methods for nanoparticles under laser heating are considered, including changes in the refractive indices of metals and spectral thermometry of optical scattering of nanoparticles, Raman spectroscopy, the thermal distortion of the refractive index of an environment heated by a nanoparticle, and thermochemical phase transitions in lipid bilayers surrounding a heated nanoparticle. Understanding the sequence of events after radiation absorption and their time scales underlies many applications of nanoparticles. The application fields for the laser heating of nanoparticles are reviewed, including thermochemical reactions and selective nanophotothermolysis initiated in the environment by laser-heated nanoparticles, thermal radiation emission by nanoparticles and laser-induced incandescence, electron and ion emission of heated nanoparticles, and optothermal chemical catalysis. Applications of the laser heating of nanoparticles in laser nanomedicine are of particular interest. Significant emphasis is given to the proposed analytical approaches to modeling and calculating the heating processes under the action of a laser pulse on metal nanoparticles, taking into account the temperature dependences of the parameters. The proposed models can be used to estimate the parameters of lasers and nanoparticles in the various application fields for the laser heating of nanoparticles.

Analytical and Numerical Models for TE-Wave Absorption in a Graded-Index GNP-Treated Cell Substrate Inserted in a Waveguide

In this paper, absorption phenomena in a hollow waveguide with an inserted graded dielectric layer are studied, for the case of transverse electric (TE) wave propagation. The waveguide model aims to be applicable to a study of a potential cancer treatment by heating of gold nanoparticles (GNPs) inside the cancer cells. In our previous work, general exact analytical fomulas for transmission, reflection, and absorption coefficients were derived. These fomulas are further developed here to be readily applicable to the calculation of the absorption coefficient within the inserted lossy layer only, quantifying the absorption in the GNP-fed cancer tissue. To this end, we define new exact analytic scale factors that eliminate unessential absorption in the surrounding lossy medium. In addition, a numerical model was developed using finite element method software. We compare the numerical results for power transmission, reflection and absorption coefficients to the corresponding results obtained from the new modified exact analytic fomulas. The study includes both a simple example of constant complex permittivities, and a more realistic example where a dispersive model of permittivity is used to describe human tissue and the electrophoretic motion of charged GNPs. The results of the numerical study with both non-dispersive and dispersive permittivities indicate an excellent agreement with the corresponding analytical results. Thus, the model provides a valuable analytical and numerical tool for future research on absorption phenomena in GNP-fed cancer tissue.

Effects of Gold Nanoparticles on Fluorescence Polarization and Emission Spectra of Rhodamine 6G Solution

Fluorescence polarization and emission spectra of Rhodamine 6G solution with gold nanoparticles have been studied. It is found that the emission intensities tend to be low when the gold nanoparticles are added into the solution partly due to the energy transfer from the Rhodamine 6G to gold nanoparticles. The fluorescence polarization increases as the concentration ratio of the gold and Rhodamine 6G is more than 124 and decreases as the ratio is about 1115. The enhancement and reduction of fluorescence polarization values are understood as the shortening of the fluorescence lifetime and a temperature effect from the heating of gold nanoparticles, respectively.

Nondestructive Approach for Additive Nanomanufacturing of Metallic Nanostructures in the Air.

In this article, a mechanism for quick release and transfer of gold nanoparticles (GNPs) from a soft substrate to another substrate under laser illumination is investigated. The heating of GNPs on a soft substrate with a continuous-wave laser causes a rapid thermal expansion of the substrate, which can be used to selectively release and place GNPs onto another surface. In-plane and out-of-plane nanostructures are successfully fabricated using this method. This rapid release-and-place process can be used for additive nonmanufacturing of metallic nanostructures under ambient conditions, which paves a way for affordable nanomanufacturing and enables a wide variety of applications in nanophotonics, ultrasensitive sensing, and nonlinear plasmonics.

Radiofrequency electric field hyperthermia with gold nanostructures: role of particle shape and surface chemistry

Hyperthermia treatment of cancerous cells has been recently developed drastically with the help of nanostructures. Heating of gold nanoparticles in non-invasive radiofrequency electric field (RF-EF) is a promising and unique technique for cancer hyperthermia. However, because of differences between particles (i.e. their surface chemistry and dispersion medium) and between RF-EF sources, the research community has not reached a consensus yet. Here, we report the results of investigations on heating of gold nanoparticles and gold nanorods under RF-EF and feasibility of in-vitro cancer hyperthermia. The heating experiments were performed to investigate the role of particle shape and surface chemistry (CTAB, citrate and PEG molecules). In-vitro hyperthermia was performed on human pancreatic cancer cell (MIA Paca-2) with PEG-coated GNPs and GNRs at concentrations that were found non-toxic based on the results of cytotoxicity assay. Application of RF-EF on cells treated with PEG-GNPs and PEG-GNRs proved highly effective in killing cells.

ID: 1044 DNA origami nanobot for sensitive drug delivery chemotherapy

The cutting-edge technology of constructing nanoscale objects using DNA origami has opened new directions for drug delivery in cancer chemotherapy research [1, 2]. This project aims to develop a novel DNA origami nanobot for drug delivery, with high selectivity and specificity for chemotherapy. It is important to be able to control the rate of drug release to maintain the concentration of chemotherapeutic agents at the desirable set-point [3]. This control can be achieved through various activation methods, similar to those used in liposome drug delivery systems, e.g. magnetism, radiation, ultrasound, heating etc. [4]. These stimuli can deliver specific types of energy (e.g. thermal), which can then activate a pre-designed nanobot- topology variation. For example, thermal energy can cause local DNA strands to melt and partially distort some local regions of the DNA topology, releasing drug molecules. One mechanism to activate the drug release is via radio frequency (RF) electromagnetic wave induced heating of gold nanoparticles [6]. A prototype nanobot will be developed and tested for heat-triggered nanobot switching between open and closed configurations. It is hypothesized that upon RF heating, the gold nanoparticles will concentrate the heat and cause the local DNA strands to melt, leading to the open configuration, without melting the rest of the nanobot structure. Heating time and power will be tuned to regulate the drug release rate. This work will develop an effective process control strategy for enhanced performance of nanoscale drug delivery systems.

Control of the optically induced heating of gold nanoparticles

Gold nanoparticles (GNPs) have proven to be good nano-sources of heat in the presence of specific electromagnetic radiation. This process, in fact, becomes strongly enhanced under plasmon resonance. In particular, the amount of generated heat and the consequent temperature increase depend on the number of GNPs that are collectively excited and on their relative distance. As a result, the regime of heat localization is deeply controlled by this last parameter. Full Text: PDF ReferencesHutter, E., and Fendler, J. H. "Exploitation of localized surface plasmon resonance". Advanced Materials 16.19, 1685-1706 (2004) CrossRef Liz-Marzán, L. M., Murphy, C. J., & Wang, J. "Nanoplasmonics". Chemical Society Reviews, 43(11), 3820-3822 (2014). CrossRef Maier, S. A. "Plasmonics: fundamentals and applications". Springer Science & Business Media (2007). CrossRef Palpant, B. "Photothermal properties of gold nanoparticles. Gold nanoparticles in physics, chemistry and biology". Imperial College Press, London, (2012). DirectLink Baffou, G. and Quidant R. "Thermo-plasmonics: using metallic nanostructures as nanosources of heat". Laser & Photonics Reviews, 7(2):171?187, (2013). CrossRef Pelton, M., Aizpurua, J., & Bryant, G. "Metal?nanoparticle plasmonics". Laser & Photonics Reviews, 2(3), 136-159 (2008). CrossRef Kreibig, U., & Vollmer, M. "Optical properties of metal clusters" (Vol. 25). Springer Science & Business Media (2013). DirectLink J., Prashant K., S. Eustis, and M. A. El-Sayed. "Plasmon coupling in nanorod assemblies: optical absorption, discrete dipole approximation simulation, and exciton-coupling model." The Journal of Physical Chemistry B 110 (37) 18243-18253 (2006). CrossRef Jain, P. K., & El-Sayed, M. A. "Surface plasmon coupling and its universal size scaling in metal nanostructures of complex geometry: elongated particle pairs and nanosphere trimmers". The Journal of Physical Chemistry C, 112(13), 4954-4960 (2008). CrossRef Chapuis, P. O., Laroche, M., Volz, S., & Greffet, J. J. "Radiative heat transfer between metallic nanoparticles". Applied Physics Letters, 92(20), 201906 (2008). CrossRef Jain, P. K., & El-Sayed, M. A. "Plasmonic coupling in noble metal nanostructures". Chemical Physics Letters, 487(4), 153-164 (2010). CrossRef Cataldi, U., Caputo, R., Kurylyak, Y., Klein, G., Chekini, M. Cesare Umeton, C., Bürgi, T. "Growing gold nanoparticles on a flexible substrate to enable simple mechanical control of their plasmonic coupling". J. Mater. Chem. C, 2, 7927-7933 (2014). CrossRef

Light-induced heating of dense 2D ensemble of gold nanoparticles: dependence on detuning from surface plasmon resonance

The extinction of white light by dense 2D ensemble of gold nanoparticles with size of 22 nm and interparticle distance of 40 nm has been studied at the simultaneous illumination of nanoparticles by the continuous-wave laser beam in dependence of the detuning of laser frequency from the surface plasmon resonance (SPR). The appreciable red shift, broadening, and increase of intensity of the plasmonic extinction band have been observed at approaching of the laser frequency to SPR. The plasmon band shift and broadening reveal the heating of gold nanoparticles that has an evident resonant character. The strong increase of nanoparticle temperature of 590 K has been observed at moderate laser intensity of 5 × 103 W/cm2 and detuning of 24.6 nm. Such strong heating is probably due to the accumulative effect and the light extinction enhancement by intense local plasmonic field of coupled Au nanoparticles in dense 2D ensemble.

Gold Nano Particles (GNPs): An Emerging Solution of Cancer

Cancer, one of the leading causes that bring confirm death, is the subject of widespread fear and taboos. Although the complete elimination of cancer hasn’t been discovered yet, “the war against cancer” has already been declared worldwide and research works are ongoing for cancer medicines. This paper presents a review on “Gold Nano Particle (GNP)”, a magic bullet which might be the timely solution to bring win against cancer malignancy. GNPs can be used as cancer drug carriers, contrast agent or in target cancer therapy etc. Because cancer cell membrane has Nano size holes, the Nano structure of GNP would help it to enter the cancer cells. It has also the dissolving abilities, so no harm would be done to other parts of the body. By using near infrared LASER, localized heating of GNPs is also possible to destroy cancer cells. Test on rats using GNPs is found successful and the implementation on human is a matter of time. In Vitro and In Vivo observations on GNPs show much promises in near future.

Implementation of a multisource model for gold nanoparticle‐mediated plasmonic heating with near‐infrared laser by the finite element method

The use of optically tunable gold nanoparticles (GNPs) in conjunction with near-infrared (NIR) laser has emerged as an attractive option for laser-induced thermal therapy (LITT), as it capitalizes on plasmonic heating of GNPs tuned to absorb light strongly in the NIR region. Previously, the authors developed a multisource model to predict the temperature change in a GNP-laden tissue-like medium illuminated by NIR laser and implemented it by a linear superposition (LS) method combining analytic and finite element method (FEM) solutions. While it is intuitive and straightforward, the LS approach might be somewhat cumbersome to implement for realistic LITT cases because it requires separate calculations of the temperature change due to individual GNP heat sources and the laser heat source. Therefore, the current investigation aimed to develop a simpler yet mathematically more elegant and computationally more efficient method solely based on FEM to implement the authors' multisource model. A multisource FEM model was developed to calculate the full spatiotemporal temperature distribution due to all heat sources (i.e., individual GNPs and the laser heat source) by solving the heat diffusion equation with multiple heat sources using FEM. This model was tested for its validity using two computational phantoms, a two-layer GNP-laden cylindrical phantom and a breast phantom with a GNP-laden microcavity. For comparison, the results for the two phantom cases were also obtained from the LS method. For the two-layer phantom case, the FEM approach resulted in a maximum temperature increase of 16.4 °C at a depth of 1.35 cm, 2.5 mm below the interface between the two layers, while the LS method produced a maximum temperature increase of 16.7 °C at a depth of 1.3 cm, 2 mm below the interface between the two layers. A comparison of the depth versus temperature changes obtained from the two approaches showed reasonably good agreement within 6%. In the breast phantom case, the LS results show a maximum temperature increase of 16.35 °C at a depth of 2.17 cm, 0.3 mm away from the center of the cavity in the direction closer to the laser. The FEM results show the same characteristics as those obtained via the LS method with a maximum temperature increase of 16.2 °C at a depth of 2.16 cm, 0.4 mm away from the center of the cavity in the direction closer to the laser. The two methods produced good agreement within 2% for the depth versus temperature distributions. The current multisource FEM model not only reproduced the results from the previous LS model, but also dramatically reduced computation time by 2 orders of magnitude, despite a generally more stringent requirement for computer memory. With further experimental validation, the FEM model can be used to predict the distinct plasmonic heating characteristics expected from NIR laser illumination of tissue-like media filled with GNPs, while offering the capability of handling heterogeneous spatial distribution of GNPs for realistic clinical cases.

Are Gold Clusters in RF Fields Hot or Not?

Heating of gold nanoparticles by radio-frequency waves, which is of interest for clinical applications, can occur if the nanoparticles are made magnetic.

Significantly Improved Analytical Sensitivity of Lateral Flow Immunoassays by Using Thermal Contrast

Heat beyond visual: The thermal contrast from the heating of gold nanoparticles upon laser stimulation can improve the analytical sensitivity of lateral flow assays (LFAs; see picture). A 32-fold improvement in sensitivity of an approved LFA for cryptococcal antigen (purple diamond) was shown, with the potential for further improvement by optimizing the backing material and the properties of the antibody-coated nanoparticles (red circle with blue Y).

A Radio-Frequency Coupling Network for Heating of Citrate-Coated Gold Nanoparticles for Cancer Therapy: Design and Analysis

Gold nanoparticles (GNPs) are nontoxic, can be functionalized with ligands, and preferentially accumulate in tumors. We have developed a 13.56-MHz RF-electromagnetic field (RF-EM) delivery system capable of generating high E-field strengths required for noninvasive, noncontact heating of GNPs. The bulk heating and specific heating rates were measured as a function of NP size and concentration. It was found that heating is both size and concentration dependent, with 5 nm particles producing a 50.6 ± 0.2 °C temperature rise in 30 s for 25 μg/mL gold (125 W input). The specific heating rate was also size and concentration dependent, with 5 nm particles producing a specific heating rate of 356 ± 78 kW/g gold at 16 μg/mL (125 W input). Furthermore, we demonstrate that cancer cells incubated with GNPs are killed when exposed to 13.56 MHz RF-EM fields. Compared to cells that were not incubated with GNPs, three out of four RF-treated groups showed a significant enhancement of cell death with GNPs (p<0.05). GNP-enhanced cell killing appears to require temperatures above 50 °C for the experimental parameters used in this study. Transmission electron micrographs show extensive vacuolization with the combination of GNPs and RF treatment.