Gold nanorods-conjugated TiO2 nanoclusters for the synergistic combination of phototherapeutic treatments of cancer cell...Published: 20 December 2018 by Springer Nature in Journal of Nanobiotechnology
Recently, a combination of photodynamic therapy (PDT) and photothermal therapy (PTT) to generate reactive oxygen species (ROS) and heat to kill cancer cells, respectively has attracted considerable attention because it gives synergistic effects on the cancer treatment by utilizing the radiation of nontoxic low-energy photons such as long wavelength visible light and near IR (NIR) penetrating into subcutaneous region. For the effective combination of the phototherapies, various organic photosensitizer-conjugated gold nanocomplexes have been developed, but they have still some disadvantages due to photobleaching and unnecessary energy transfer of the organic photosensitizers. In this study, we fabricated novel inorganic phototherapeutic nanocomplexes (Au NR–TiO2 NCs) by conjugating gold nanorods (Au NRs) with defective TiO2 nanoparticle clusters (d-TiO2 NP clusters) and characterized their optical and photothermal properties. They were observed to absorb a broad range of visible light and near IR (NIR) from 500 to 1000 nm, exhibiting the generation of ROS as well as the photothermal effect for the simultaneous application of PDT and PTT. The resultant combination of PDT and PTT treatments of HeLa cells incubated with the nanocomplexes caused a synergistic increase in the cell death compared to the single treatment. The higher efficacy of cell death by the combination of PDT and PTT treatments with the nanocomplexes is likely attributed to the increases of ROS generation from the TiO2 NCs with the aid of local surface plasma resonance (LSPR)-induced hot electrons and heat generation from Au NRs, suggesting that Au NR–TiO2 NCs are promising nanomaterials for the in vivo combinatorial phototherapy of cancer. The online version of this article (10.1186/s12951-018-0432-4) contains supplementary material, which is available to authorized users.
Sanitization of Data in Nanoscale Flash Memory by Thermal Erasing and Reuse of Storage (Phys. Status Solidi A 14∕2018)Published: 24 July 2018 by Wiley in physica status solidi (a)
This study, a thermal method for erasing and permanently destroying data stored in flash memory fabricated on a suspended silicon nanowire is demonstrated. An intentionally applied heat treatment is used to erase the data stored in the charge trap layer of the flash memory. The data destruction is verified and analyzed at a unit cell level as well as in a commercial off‐the‐shelf chip. Characteristics of memory performance and reliability are also investigated. Then, the feasibility of the proposed method is further evaluated for next generation 3‐dimensional V‐NAND.
Sub-surface Thermal Imaging of Microelectronic Devices using Confocal Laser Scanning Thermoreflectance MicroscopyPublished: 01 January 2018 by The Optical Society in Imaging and Applied Optics 2018 (3D, AO, AIO, COSI, DH, IS, LACSEA, LS&C, MATH, pcAOP)
We report on a confocal thermoreflectance imaging system, which provides the elimination of out-of-focus reflections, and demonstrate the improvement of ~23 times in the sensitivity due to the confocality during the sub-surface thermoreflectance measurement.
Investigation of Self-Heating Effects in Gate-All-Around MOSFETs With Vertically Stacked Multiple Silicon Nanowire Chann...Published: 01 November 2017 by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Electron Devices
The self-heating effects (SHEs) in gate-all-around (GAA) MOSFETs with vertically stacked silicon nanowire (SiNW) channels are investigated. Direct observations using thermal images, electrical proof measurements, and supportive numerical simulations are carried out to verify the SHEs. This paper examines the location of hot spots as well as heat dissipation paths (heat sink) depending on the device geometry, and the electrical degradation produced by the SHEs. It also includes the estimation of the surface temperature of the GAA MOSFET and the average temperature across the bulk channel. Design parameters for improved management of the heat dissipation in a device are suggested. This investigation can contribute to improve the device performance and reliability of a 3-D stacked structure.
A new technique is proposed for the activation of low temperature amorphous InGaZnO thin film transistor (a-IGZO TFT) backplanes through application of a bias voltage and annealing at 130 °C simultaneously. In this 'electrical activation', the effects of annealing under bias are selectively focused in the channel region. Therefore, electrical activation can be an effective method for lower backplane processing temperatures from 280 °C to 130 °C. Devices fabricated with this method exhibit equivalent electrical properties to those of conventionally-fabricated samples. These results are analyzed electrically and thermodynamically using infrared microthermography. Various bias voltages are applied to the gate, source, and drain electrodes while samples are annealed at 130 °C for 1 hour. Without conventional high temperature annealing or electrical activation, current-voltage curves do not show transfer characteristics. However, electrically activated a-IGZO TFTs show superior electrical characteristics, comparable to the reference TFTs annealed at 280 °C for 1 hour. This effect is a result of the lower activation energy, and efficient transfer of electrical and thermal energy to a-IGZO TFTs. With this approach, superior low-temperature a-IGZO TFTs are fabricated successfully.
Numerical analysis for characterization of the gold nanorod mediated-plasmonic heating with temporary NIR laser radiatio...Published: 17 September 2016 by SPIE-Intl Soc Optical Eng in Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XIV
Over the last decade, plasmonic photothermal therapy (PPTT) has received significant attention as the new therapeutic strategy for the cancer therapy due to unique characteristics of the gold-nanoparticles. The characterization of the spatiotemporal heating potential for the gold nanorods (GNR) through mimicking PPTT process on the various conditions can help more quantitative approaches to treatment planning. The purpose of this study was to clearly understand the optical-thermal interactions between the laser, GNRs, and bio-tissues, and provide the information in clinical applications to implement the concept of heterogeneity, which can enable the optimization of treatment parameters for superficial breast cancer treatment. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Photothermal therapy (PT) provides a strong potential in treatment of tumors, selective cell death, through the ability of gold nanoparticles to target destructive heat preferentially to tumor regions. And yet, clinical application of the thermal therapies has not accomplished due to insufficient processes of the heating methods and temperature measuring techniques leading to low reproducibility of such treatment. In this study, we created a 3 dimensional tissue platform to characterize the heating method and to control the generated heat in the tissue used for a superficial cancer model using gold nanorods (GNRs) and near-infrared (NIR, 808 nm) laser. The 3D tissue platform involved a 2 mm wide hemisphere to confine the GNRs covered with20 μm thick polymer film designed to mimic localized nanoparticles in tumor. Moreover, this platform provides an easy way to measure heat distribution and temperature created in tumor cross section. To investigate the photothermal effect of GNRs on heat generation, the amount of GNRs and laser power density were controlled. The GNRs were shown to be the large absorption cross sections generating localized photothermal effects and hyperthermic effects on destructive consequences in the cell dynamics causing a partial tumor regression. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Quantitative temperature measurement of multi-layered semiconductor devices using spectroscopic thermoreflectance micros...Published: 14 June 2016 by The Optical Society in Optics Express
Thermoreflectance microscopy is essential in understanding the unpredictable local heating generation that occurs during microelectronic device operation. However, temperature measurements of multi-layered semiconductor devices represent a challenge because the thermoreflectance coefficient is quite small and is dramatically changed by the optical interference inside transparent layers of the device. Therefore, we propose a spectroscopic thermoreflectance microscopy system using a systematic approach for improving the quantitative temperature measurement of multi-layered semiconductor devices. We demonstrate the quantitative measurement of the temperature profile for physical defects on thin-film polycrystalline silicon resistors via thermoreflectance coefficient calibration and effective coefficient κ estimation.
High-sensitive Thermoreflectance Measurement for Multi-layered Semiconductor Devices using Multi-spectral Thermoreflecta...Published: 01 January 2016 by The Optical Society in CLEO: 2015
We demonstrate a thermoreflectance microscope system and their applications, such as surface temperature measurement of semiconductor devices, hot spot detection for failure analysis of integrated circuits, and detection of defects in optical materials for high power laser.
We demonstrate a thermal imaging microscope system that measures the temperature distribution over the surface of microelectronic devices. It enables hot spot detection and thermal analysis of microelectronics devices
Hydrothermal synthesis of defective TiO 2 nanoparticles for long-wavelength visible light-photocatalytic killing of canc...Published: 01 January 2015 by Royal Society of Chemistry (RSC) in RSC Advances
Newly fabricated d -TiO 2 NPs were demonstrated to be efficient in long wavelength visible light-triggered killing of cancer cells. Defective TiO 2 nanoparticles ( d -TiO 2 NPs) were successfully synthesized using a simple hydrothermal technique through the formation of liposome–TiO 2 composites using P25 TiO 2 powder as the starting material. The morphology and vibrational structures of the d -TiO 2 NPs were characterized by various techniques, including X-ray diffraction, transmission electron microscopy, and Fourier transform-infrared and Raman spectroscopic analyses. The synthesized d -TiO 2 NPs were composed of both the rutile and anatase phases of TiO 2 with a diameter of approximately 25 nm, and they exhibited absorption of broad visible light including near-infrared wavelengths, from 400 nm to 1000 nm, which was confirmed by diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The agglomeration size of the d -TiO 2 NPs in aqueous solution was lesser (224 nm) than that of P25 TiO 2 (1440 nm). Therefore, the synthesized d -TiO 2 NPs could more easily infiltrate the membrane and cytoplasm of cancer cells via endocytosis than could P25 TiO 2 . Consequently, upon irradiation with long-wavelength visible light (400–800 nm), the d -TiO 2 NPs could generate reactive oxygen species, including singlet oxygen, leading to the destruction of cancer cells. These results suggest that the newly fabricated d -TiO 2 NPs are promising nanomaterials for future in vivo photodynamic therapy of cancer.
Kisoo Chang participated at conference 4th International Symposium on Sensor Science.