• Asian Pacific Journal of Cancer Prevention
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• v.16 no.16
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• pp.7003-7006
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• 2015

Background: Nanoparticles of gold and silver are offering revolutionary changes in the field of cancer therapy. N-heterocyclic carbene (NHC) metal complexes possess diverse biological activities and are being investigated as potential chemotherapeutic agents. The purpose of this study was to examine the cytotoxicity and possible mechanisms of action of two types of newly synthesized nanofiber composites containing BIAN N-heterocyclic gold carbene complexes in two types of human cancer cells, namely breast cancer (MCF7) and liver cancer (HepG2) cells and also in normal human embryonic kidney cells (HEK 293). Materials and Methods: Cytotoxicity was assessed by MTT cell viability assay and oxidative stress by checking the total glutathione level. Results: Both compounds affected the cell survival of the tested cell lines at very low concentrations (IC50 values in the micro molar range) as compared to a well-known anti-cancer drug, 5 fluorouracil. A 60-80% depletion in total glutathione level was detected in treated cells. Conclusions: Reduction in total glutathione level is one of the biochemical pathways for the induction of oxidative stress which in turn could be a possible mechanism of action by which these compounds induce cytotoxicity in cancer cell lines. The in vitro toxicity towards cancer cells found here means that these molecules could be potential anticancer candidates.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.264-264
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• 2012

As an environment-friendly alternative energy resource, ethanol may be used to obtain hydrogen, a clean energy source. Thus, studies on catalytic reactions involving ethanol have been studied to understand the underlying principles in the reaction mechanism using various oxide-supported catalysts. Among them, Au-based catalysts have shown a superior activity in producing hydrogen gas. In the present study, Au/$TiO_2$ catalysts were prepared by deposition-precipitation method to understand their catalytic activities toward ethanol and acetaldehyde with increasing gold loading, especially at the very low Au loading regime. A commercially available $TiO_2$ (Degussa P-25) was employed and the Au loading was varied to 0, 0.1, 0.5, and 1.0 wt% respectively. The catalysts showed characteristic x-ray diffraction (XRD) features at $2{\theta}=78.5^{\circ}$ that could be assigned to the presence of gold nanoparticles. Its reactivity measurements were performed under a constant flow of ethanol and acetaldehyde at a flow rate of ${\sim}0.6{\mu}mol/sec$ and the substrate temperature was slowly raised at a rate of 0.2 K/sec. We observed that the overall reactivity of the catalysts increased with increasing Au loading along with selectivity favoring dehydrogenation to product hydrogen gas. In addition, we disclosed various reaction channels involving competitive reaction paths such as dehydrogenation, dehydration, and condensation. In addition, subsequent reactions of acetaldehyde obtained from dehydrogenation of ethanol, were found to occur and produce butene, crotonaldehyde, furan, and benzene. Based on the results, we proposed overall reaction pathways of such reaction channels.

• Food Science of Animal Resources
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• v.43 no.1
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• pp.73-84
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• 2023

Campylobacteriosis is a common cause of gastrointestinal disease. In this study, we suggest a general strategy of applying gold nanoparticles (AuNPs) in colorimetric biosensors to detect Campylobacter in chicken carcass. Polymerase chain reaction (PCR) was utilized for the amplification of the target genes, and the thiolated PCR products were collected. Following the blending of colloid AuNPs with PCR products, the thiol bound to the surface of AuNPs, forming AuNP-PCR products. The PCR products had a sufficient negative charge, which enabled AuNPs to maintain a dispersed formation under electrostatic repulsion. This platform presented a color change as AuNPs aggregate. It did not need additional time and optimization of pH for PCR amplicons to adhere to the AuNPs. The specificity of AuNPs of modified primer pairs for mapA from Campylobacter jejuni and ceuE from Campylobacter coli was activated perfectly (C. jejuni, p-value: 0.0085; C. coli, p-value: 0.0239) when compared to Salmonella Enteritidis and Escherichia coli as non-Campylobacter species. Likewise, C. jejuni was successfully detected from artificially contaminated chicken carcass samples. According to the sensitivity test, at least 15 ng/μL of Campylobacter PCR products or 1×10³ CFU/mL of cells in the broth was needed for the detection using the optical method.

• Progress in Medical Physics
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• v.33 no.4
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• pp.114-120
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• 2022

Purpose: Particle beam therapy is advantageous over photon therapy. However, adequately delivering therapeutic doses to tumors near critical organs is difficult. Nanoparticle-aided radiation therapy can be used to alleviate this problem, wherein nanoparticles can passively accumulate at higher concentrations in the tumor tissue compared to the surrounding normal tissue. In this study, we investigate the dose enhancement effect due to gold nanoparticle (GNP) when Carbon-12, He-4, and proton beams are irradiated on GNP. Methods: First, monoenergetic Carbon-12 and He-4 ion beams of energy of 283.33 MeV/u and 150 MeV/u, respectively, and a proton beam of energy of 150 MeV were irradiated on a water phantom of dimensions 30 cm×30 cm×30 cm. Subsequently, the secondary-particle information generated near the Bragg peak was recorded in a phase-space (phsp) file. Second, the obtained phsp file was scaled down to a nanometer scale to irradiate GNP of diameter 50 nm located at the center of a 4 ㎛×4 ㎛×4 ㎛ water phantom. The dose enhancement ratio (DER) was calculated in intervals of 1 nm from the GNP surface. Results: The DER of GNP computed at 1 nm from the GNP surface was 4.70, 4.86, and 4.89 for Carbon-12, He-4, and proton beams, respectively; the DER decreased rapidly with increasing distance from the GNP surface. Conclusions: The results indicated that GNP can be used as radiosensitizers in particle beam therapy. Furthermore, the dose enhancement effect of the GNP absorbed by tumor cells can aid in delivering higher therapeutic doses.

• Journal of the Optical Society of Korea
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• v.18 no.3
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• pp.274-282
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• 2014

In this study, closely spaced Au nanoparticles which are arranged in nanocluster (heptamer) configurations have been employed to design efficient plasmonic subwavelength devices to function at the telecommunication spectrum (${\lambda}$~1550 nm). Utilizing two kinds of nanoparticles, the optical properties of heptamer clusters composed of Au rod and shell particles that are oriented in triphenylene molecular fashion have been investigated numerically, and the cross-sectional profiles of the scattering and absorption of the optical power have been calculated based on a finite-difference time-domain (FDTD) method. Plasmon hybridization theory has been utilized as a theoretical approach to characterize the features and properties of the adjacent and mutual heptamer clusters. Using these given nanostructures, we designed a complex four-branch ($1{\times}4$) Y-shape splitter that is able to work at the near infrared region (NIR). This splitter divides and transmits the magnetic plasmon mode along the mutual heptamers arrays. Besides, as an important and crucial parameter, we studied the impact of arm spacing (offset distance) on the guiding and dividing of the magnetic plasmon resonance propagation and by calculating the ratio of transported power in both nanorod and nanoshell-based structures. Finally, we have presented the optimal structure, that is the four-branch Y-splitter based on shell heptamers which yields the power ratio of 23.9% at each branch, 4.4 ${\mu}m$ decaying length, and 1450 nm offset distance. These results pave the way toward the use of nanoparticles clusters in molecular fashions in designing various efficient devices that are able to be efficient at NIR.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.9 no.1
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• pp.9-16
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• 2023

Liposomes as drug delivery system have proved useful carrier for various disease, including cancer. In addition, perfluorocarbon cored microbubbles are utilized in conjunction with high-intensity focused-ultrasound (HIFU) to enable simultaneous diagnosis and treatment. However, microbubbles generally exhibit lower drug loading efficiency, so the need for the development of a novel liposome-based drug delivery material that can efficiently load and deliver drugs to targeted areas via HIFU. This study aims to develop a liposome-based drug delivery material by introducing a substance that can burst liposomes using ultrasound energy and confirm the ability to target tumors using PET imaging. Liposomes (Lipo-DOX, Lipo-DOX-Au, Lipo-DOX-Au-RGD) were synthesized with gold nanoparticles using an avidin-biotin bond, and doxorubicin was mounted inside by pH gradient method. The size distribution was measured by DLS, and encapsulation efficiency of doxorubicin was analyzed by UV-vis spectrometer. The target specificity and cytotoxicity of liposomes were assessed in vitro by glioblastoma U87mg cells to HIFU treatment and analyzed using CCK-8 assay, and fluorescence microscopy at 6-hour intervals for up to 24 hours. For the in vivo study, U87mg model mouse were injected intravenously with 1.48 MBq of ⁶⁴Cu-labeled Lipo-DOX-Au and Lipo-DOX-Au-RGD, and PET images were taken at 0, 2, 4, 8, and 24 hours. As a result, the size of liposomes was 108.3 ± 5.0 nm at Lipo-DOX-Au and 94.1 ± 12.2 nm at Lipo-DOX-Au-RGD, and it was observed that doxorubicin was mounted inside the liposome up to 52%. After 6 hours of HIFU treatment, the viability of U87mg cells treated with Lipo-DOX-Au decreased by around 20% compared to Lipo-DOX, and Lipo-DOX-Au-RGD had a higher uptake rate than Lipo-DOX. In vivo study using PET images, it was confirmed that ⁶⁴Cu-Lipo-DOX-Au-RGD was taken up into the tumor immediately after injection and maintained for up to 4 hours. In this study, drugs released from liposomes-gold nanoparticles via ultrasound and RGD targeting were confirmed by non-invasive imaging. In cell-level experiments, HIFU treatment of gold nanoparticle-coupled liposomes significantly decreased tumor survival, while RGD-liposomes exhibited high tumor targeting and rapid release in vivo imaging. It is expected that the combination of these models with ultrasound is served as an effective drug delivery material with therapeutic outcomes.

• The Journal of the Acoustical Society of Korea
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• v.35 no.6
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• pp.473-479
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• 2016

We report a highly selective and sensitive 200 MHz Surface Acoustic Wave (SAW) sensor that can detect cyanide ion in aqueous solution using surface immobilized thioester molecules in combination with gold nanoparticles (AuNPs). To construct the sensor device, a monolayer of thioester compound was immobilized on the SAW sensor surface. At the sensor surface, hydrolysis of thioester group by nucleophilic addition of cyanide occurred and the resulting free thiol unit bound to AuNP to form thiol-AuNP conjugate. For the signal enhancement, gold staining signal amplification process was introduced subsequently with gold (III) chloride trihydrate and reducing agent, hydroxylamine hydrochloride. The SAW sensor showed a detection ability of $17.7{\mu}M$ for cyanide in aqueous solution and demonstrated a saturation behavior between the frequency shift and the concentration of cyanide ion. On the other hand, our SAW sensor had no activities for other anions such as fluoride ion, acetate ion and sulfate ion, moreover, no significant interference observed by other anions. Finally, all the experiments were carried out in-house developed sensor and fluidics modules to obtain highly reproducible results.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.200-205
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• 2016

A drug transport carrier could be used for safe send of drugs to the affected region in a human body. The chitosan is adequate for the drug delivery carrier because of adaptable to living body. The gold, a metallic nanoparticles, tends to form a nano complex at rapidly when it combined with chitosan because of its negative charge. having energy from the other, outer gold nano-complex make heat due to its property to release the contained drugs to the target area. Silver could be also formed an useful biocompatible nano-composites with chitosan which should be used as an useful drug transfer carrier because its special ability to protect microbial contamination. Being one of the oxidized nano metals, $Fe_3O_4$ is nontoxic and has been used for its magnetic characteristics. In this study, the control of catalyst, reducing agent, and solvent amount. The chitosan-$Fe_3O_4$-gold & silver nanoshell have been changed to form about 100 nm size by ionic bond between the amine group, an end group of chitosan, and the metal. It was observed the change in order to seek for its optimum reaction condition as a drug transfer carrier.

• Carbon letters
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• v.24
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• pp.47-54
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• 2017

Different phytochemicals obtained from various natural plant sources are used as reduction agents for preparing gold, copper, silver and platinum nanoparticles. In this work a green method of reducing graphene oxide (rGO) by an inexpensive, effective and scalable method using olive leaf aqueous extract as the reducing agent, was used to produce rGO. Both GO and rGO were prepared and investigated by ultraviolet and visible spectroscopy, Fourier-transform infrared, scanning electron microscopy, atomic force microscopy, thermogravimetric analysis, cyclic voltammetry, X-ray photoelectron spectra, electrochemical impedance spectroscopy and powder X-ray diffraction.

• Journal of Sensor Science and Technology
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• v.17 no.2
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• pp.95-99
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• 2008

Various etching methods of optical fiber and formation of metal nano particles on the optical fiber have been proposed for fabrication of fiber optic localized surface plasmon resonance (FO LSPR) biosensors. Different types of etched optical fiber are possible by removing the cladding of optical fiber using HF (hydrofluoric acid) solution and BHF (buffered hydrofluoric acid) solution, which results in improved surface roughness when BHF solution is used. Localized surface plasmon can be formed and measured by formation of silver and gold nano particles on the etched optical fiber. The characteristics of the etched optical fiber and metal nano particles on the etched surface of the optical fiber play a key role in dictating the sensitivity of the LSPR sensors, so that the proposed results can be expected to be applied for related research on fiber optic based biosensors.