A STUDY ON THE HEATING PROCESS OF GOLD NANOPARTICLES IN LASER NANO MEDICINE

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ALAEE ZAHRA; MOHAMMAD NEJAD SHAHRAM

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Journal: Lasers in Medicine Year:2010 | Volume:7 | Issue:3 (37) Page(s): 18-24

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Title

A STUDY ON THE HEATING PROCESS OF GOLD NANOPARTICLES IN LASER NANO MEDICINE

Author(s)

ALAEE ZAHRA | MOHAMMAD NEJAD SHAHRAM | Issue Writer Certificate

Keywords

NANOPARTICLESQ2

LASER PULSESQ3

HEATING DYNAMICQ3

Abstract

Introduction: Ultrashort laser pulse heating has recently attracted much attention about selective damage for cancer cells, bacteria, viruses and DNA. Short pulses concentrate high laser energies on extremely small metallic nanoparticle, and the photons are absorbed by free electrons within the metal and transferred to the lattice subsystem and then to the surrounding medium. Therefore, this nanoparticle provides highly selective heat transfer from ultra-short pulses to the target cells. Simulation of this process provides an effective method and the results of it can be used for further nano medicine practical research.Material and methods: Among different nanostructures, gold NANOPARTICLES are the most promising candidates for photo thermal process since they are strong absorbers, photostable, and nontoxic, easily conjugated to proteins and have adjustable optical properties. There are two models for calculating temperature of electrons and crystal lattice of NANOPARTICLES. The first temperature model utilizes similar temperatures for electrons and lattice and the second temperature model that is used for ultrashort LASER PULSES. Short pulses are ended before complete transfer of electron energy to the lattice and then the temperature of electron and lattice is different. In this paper, simulation results on the heating process of gold NANOPARTICLES after irradiation by ultrashort LASER PULSES femtosecond, picosecond and nanosecond are presented. We use a model utilizing the uniform heating approximation and the small size of NANOPARTICLES in comparison to the wavelength of laser radiation, and then it was confirmed that this model is appropriate approximation for NANOPARTICLES heating in the femtosecond, picosecond and nanosecond regimes. It shows that during the laser pulse duration. The transfer of heat from the NANOPARTICLES into the surrounding media is slight but when the laser pulse has degraded, the transfer of heat from the particle to the surrounding medium becomes increasingly important. In nanosecond regime, because of longer pulse duration, this heat transfer is higher than others and the temperature of particle rapidly decreases. The effects of the different biological surrounding media blood, human prostate, tumor and fat are investigated.Results: Due to the relatively low thermal conductivity of fat as compared to the other biomedia fat has low thermal characteristics and we observe higher heating of the particles at the same energy level and pulse duration. This study will compare thermal calculations for 30 nm gold NANOPARTICLES, which are heated and cooled in water at different heat that losts transfer rates for femtosecond, picosecond and nanosecond regimes. The temperature dynamics of the particle is sensitive to the temperature dependence of the heat lost from the surface of the NANOPARTICLES into the surrounding medium. In the femtosecond regime, pulse duration is very small and medium with high thermo physical characteristics cannot change the temperature greatly, but in the picoseconds and nanosecond regimes, medium with low thermal conductivity can alter the temperature of NANOPARTICLES very much. By reviewing the other research, it is confirmed that theoretical results coincide to practical attempts. Maximum temperature for femto, pico and nanosecond is 1020, 1005 and 7000 K for 1mJ/cm2, 1mJ/cm2 and 10mJ/cm2 pulse laser intensities respectively. Also it is concluded that two temperature model only are used to femtosecond regime that electron temperature is different from lattice temperature, but this method is not used for longer pulses (pico & nano second pulses) and because of ignoring heat transfer to surrounding medium, its results are not correction.Conclusion: Results of this article show the first temperature model is appropriate method for understanding short laser pulse interaction to metallic NANOPARTICLES, So that for NANOPARTICLES that are smaller than laser wavelength, time delay is negligible and results are similar to the second temperature model.

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APA: Copy

ALAEE, ZAHRA, & MOHAMMAD NEJAD, SHAHRAM. (2010). A STUDY ON THE HEATING PROCESS OF GOLD NANOPARTICLES IN LASER NANO MEDICINE. LASER IN MEDICINE, 7(3 (37)), 18-24. SID. https://sid.ir/paper/113505/en

Vancouver: Copy

ALAEE ZAHRA, MOHAMMAD NEJAD SHAHRAM. A STUDY ON THE HEATING PROCESS OF GOLD NANOPARTICLES IN LASER NANO MEDICINE. LASER IN MEDICINE[Internet]. 2010;7(3 (37)):18-24. Available from: https://sid.ir/paper/113505/en

IEEE: Copy

ZAHRA ALAEE, and SHAHRAM MOHAMMAD NEJAD, “A STUDY ON THE HEATING PROCESS OF GOLD NANOPARTICLES IN LASER NANO MEDICINE,” LASER IN MEDICINE, vol. 7, no. 3 (37), pp. 18–24, 2010, [Online]. Available: https://sid.ir/paper/113505/en

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