Tae Hyun Yoon

Abstract : Development of nanotoxicity prediction models is becoming increasingly important in the risk assessment of engineered nanomaterials. However, it has significant obstacles caused by the wide heterogeneities of published literature in terms of data completeness and quality. Here, we performed a meta-analysis of 216 published articles on oxide nanoparticles using 14 attributes of physicochemical, toxicological and quantum-mechanical properties. Particularly, to improve completeness and… 더보기

Abstract : Development of nanotoxicity prediction models is becoming increasingly important in the risk assessment of engineered nanomaterials. However, it has significant obstacles caused by the wide heterogeneities of published literature in terms of data completeness and quality. Here, we performed a meta-analysis of 216 published articles on oxide nanoparticles using 14 attributes of physicochemical, toxicological and quantum-mechanical properties. Particularly, to improve completeness and quality of the extracted dataset, we adapted two preprocessing approaches: data gap-filling and physicochemical property based scoring. Performances of nano-SAR classification models revealed that the dataset with the highest score value resulted in the best predictivity with compromise in its applicability domain. The combination of physicochemical and toxicological attributes was proved to be more relevant to toxicity classification than quantum-mechanical attributes. Overall, by adapting these two preprocessing methods, we demonstrated that meta-analysis of nanotoxicity literatures could provide an effective alternative for the risk assessment of engineered nanomaterials. 더보기 취소

Abstract
Agglomeration of nanoparticles (NPs) in cell culture media can alter their physicochemical properties and colloidal behaviour, which may affect their cellular association and cytotoxicity. Herein, we investigated the impact of agglomeration of silver NPs on their effective dose and cellular association under various in vitro assay conditions. Hydrodynamic sizes, zeta potentials, and effective densities of agglomerates were characterized for two different types of positively charged… 더보기

Abstract
Agglomeration of nanoparticles (NPs) in cell culture media can alter their physicochemical properties and colloidal behaviour, which may affect their cellular association and cytotoxicity. Herein, we investigated the impact of agglomeration of silver NPs on their effective dose and cellular association under various in vitro assay conditions. Hydrodynamic sizes, zeta potentials, and effective densities of agglomerates were characterized for two different types of positively charged silver NPs with nominal core sizes of 60 nm and 100 nm. Then, three different dose metrics (administered, effective, and cellular doses) under upright and inverted exposure configurations were compared with the measured physicochemical properties and colloidal behaviours. Changes in the agglomeration characteristics, such as an increment in the hydrodynamic size and a decrement in the effective density, assisted the sedimentation and reduced the diffusion of NPs, leading to a higher effective dose and cellular association in the upright configuration than in the inverted configuration. From the comparison between the two sizes, we have observed that agglomerates of NPs with smaller core diameters could be less stably suspended in the biological media and thus, have higher effective doses and cellular association than agglomerates of NPs with larger core sizes, depending on their agglomeration process. Therefore, the agglomeration characteristics, rather than the intrinsic properties of the bare NPs, seem to have a more important role in determining the effective dose and cellular association of NPs and would be more relevant to understanding cell–nanoparticle interactions and their resultant cytotoxicity. 더보기 취소

Colloidal crystals composed of micro- or nano- colloids have been investigated in various fields such as photonics due to their unique optical properties. Binary colloidal crystals have an outstanding potential for fine-tuning material properties by changing the components, concentration, or size of colloids. Because of their tunable optical, electrical, magnetic, and mechanical properties, those materials attracted great attention. However, it has been hard to elucidate internal structures… 더보기

Colloidal crystals composed of micro- or nano- colloids have been investigated in various fields such as photonics due to their unique optical properties. Binary colloidal crystals have an outstanding potential for fine-tuning material properties by changing the components, concentration, or size of colloids. Because of their tunable optical, electrical, magnetic, and mechanical properties, those materials attracted great attention. However, it has been hard to elucidate internal structures without fluorescent labelling or cross-sectioning. Here, we demonstrate the structural analysis of not only unary but also binary colloidal crystals using scanning transmission x-ray microscopy and compare the results with colloidal structures and optical properties observed by optical microscopy. Based on the comparison of images obtained by these two methods, the domains of colloidal crystals consisting of different structures and colours were directly identified without any additional sample preparation. Therefore, it was possible to investigate the structural colours of local domains of unary and binary colloidal crystals such as the face centred cubic (FCC) structure with different orientations, that is FCC (111) and FCC (001), and hexagonal close-packed structure, HCP (0001). 더보기 취소

There has been a great deal of research regarding the cellular association of nanoparticles (NPs), although there are only a few methods available yet for the quantitative measurements of cellular NPs. In this study, we propose a simple and quantitative method to estimate the cellular uptake of Au NPs into cervical cancer cells (HeLa) based on their side scattering (SSC) intensities measured by flow cytometry (FCM). We have compared SSC intensities of HeLa cells exposed to eight different types… 더보기

There has been a great deal of research regarding the cellular association of nanoparticles (NPs), although there are only a few methods available yet for the quantitative measurements of cellular NPs. In this study, we propose a simple and quantitative method to estimate the cellular uptake of Au NPs into cervical cancer cells (HeLa) based on their side scattering (SSC) intensities measured by flow cytometry (FCM). We have compared SSC intensities of HeLa cells exposed to eight different types of Au NPs (40–100 nm size, with positive or negative surface charge) with the amount of cellular Au NPs measured by inductively coupled plasma mass spectrometry (ICPMS). On the basis of these comparisons, we have found linear correlations between the cellular Au NPs and the SSC intensities and used them to estimate the amount of Au NPs associated with HeLa cells. Once the correlations were found for specific cell lines and types of nanoparticles, this approach is useful for simple and quantitative estimation of the cellular Au NPs, without performing labor-intensive and complicated sample preparation procedures required for the ICPMS approach. 더보기 취소