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ABSTRACT: Thiol group functionalized silica-coated magnetic nanoparticles (Si-MNPs@SH) were synthesized for rapid and selective magnetic field-based separation of mixed proteins. The highest adsorption efficiencies of binary proteins, bovine serum albumin (BSA; 66 kDa; pI = 4.65) and lysozyme (LYZ; 14.3 kDa; pI = 11) were shown at the pH values corresponding to their own pI in the single-component protein. In the mixed protein, however, the adsorption performance of BSA and LYZ by Si-MNPs@SH was governed not only by pH but also by the molecular weight of each protein in the mixed protein.
Nanoscale Research Letters 05/2012; 7(1):279. · 2.73 Impact Factor
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ABSTRACT: This work reports on the realization of specific functionalized silica-coated magnetic nanoparticles (Si-MNPs) for effective protein separation through surface modification with various amino acid side chain-like functional groups such as thiol (-SH), disulfide (-S-S-), carbon chain (-C(n)), carboxyl (-COOH), amine (-NH(2)), and aldehyde (-CHO). This study also suggests an improved and convenient method for the synthesis of functionalized Si-MNPs by hydrolysis condensation with silan-coupling agents. The protein adsorption effects in a coexistent mixed state are explored using various proteins, which have different isoelectric point (pI) values and molecular weights, in order to elucidate the binding performance of different proteins one solution. The adsorption efficiency of bovine serum albumin (BSA; 66 kDa; pI=4.65) and lysozyme (LYZ; 14.3 kDa; pI=11) is 70-100% with various amino acid side chain-like functional groups. However, the adsorption efficiency of a mixed protein solution of BSA and LYZ was different. Although the relatively bulky BSA molecule displayed 50% and 20% adsorption corresponding to pH 4.65, and pH 11, respectively, the smaller LYZ provided almost 100% adsorption at both pH 4.65 and pH 11.
Talanta 05/2012; 93:160-5. · 3.79 Impact Factor
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ABSTRACT: The aims of this study were to determine the sorption coefficient (LogK(DOC)) of 17β-estradiol (E2), according to the size and composition of dissolved organic matter (DOM) isolated from wastewater effluent using a fluorescence quenching (FQ) method, and to measure the estrogenic changes due to the extent of E2 sorption onto effluent DOM (EfOM) by using an E-screen bioassay. The highest logK(DOC) of E2 for a DOM size fraction less than 0.2 μm was observed by 4.87 ± 1.87 Lkg(-1)(DOC), and its estrogenicity was the lowest among all the size fractions at 1.2 ng-EEQL⁻¹. However, E2 estrogenicity for a DOM size fraction less than 5 kDa was as high as that for the positive control due to the absence of fulvic acid- and protein-like DOM to bind with E2. The estrogenic activity for the hydrophobic fraction bound with E2 was significantly reduced to 1.6 ng-EEQL⁻¹, while that for the hydrophilic fraction having no binding with E2 was 2.6 ng-EEQL⁻¹, which was similar to that of the positive control (i.e., 2.8 ng-EEQL⁻¹). The results support a conclusion that the change in estrogenicity was due to the strong sorption affinity of E2 onto DOM.
Ecotoxicology and Environmental Safety 03/2011; 74(5):1280-7. · 2.29 Impact Factor
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ABSTRACT: Over the years, nanostructures have been developed to enable to support enzyme usability to obtain highly selective and efficient biocatalysts for catalyzing processes under various conditions. This review summarizes recent developments in the nanostructures for enzyme supporters, typically those formed with various inorganic materials. To improve enzyme attachment, the surface of nanomaterials is properly modified to express specific functional groups. Various materials and nanostructures can be applied to improve both enzyme activity and stability. The merits of the incorporation of enzymes in inorganic nanomaterials and unprecedented opportunities for enhanced enzyme properties are discussed. Finally, the limitations encountered with nanomaterial-based enzyme immobilization are discussed together with the future prospects of such systems.
BMB reports 02/2011; 44(2):77-86. · 1.72 Impact Factor
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ABSTRACT: Broad scale monitoring of estrogenic compounds was performed at 19 sampling points throughout the Yeongsan and Seomjin river basins and 5 wastewater treatment plants (WWTPs) adjacent to the Gwangju area, Korea, from December 2005 to August 2007. The concentrations of estrogenic compounds, including estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), bisphenol-A, nonylphenol (NP) and 4-octylphenol (OP), in the samples was measured with gas chromatography/mass spectrometry (GC-MS). In addition, the estrogenic activities throughout the river were investigated using the E-screen assay. Of the six estrogenic chemicals, NP (114.6-336.1 ng L(-1)) and EE2 (0.23-1.90 ng L(-1)) were detected at the highest and lowest levels, respectively in both the river waters and the WWTP effluents. Bisphenol-A showed the largest concentration range, from 7.5 to 335 ng L(-1). The concentrations of E1, E2 and octylphenol ranges were 3.6-69.1, 1.2-10.7, and 2.2-16.9 ng L(-1), respectively. According to the calculated estradiol equivalent concentration (EEQ); however, no estrogenic contribution was observed due to the phenolic compounds in the river waters and effluents. E1 and E2 dominated in both the river water and effluent samples, with contributions to the calculated EEQ of over 79 and 77%, respectively. Conversely, EE2 was rarely detected in the river waters (21%) and effluents (0%). The largest contribution of EE2 to the calculated EEQ was 21% in the river water at S-7. The levels of E1, E2, and EE2 were remarkably decreased in the effluents, indicating that the 5 WWTPs did not contribute to the estrogenic effect of the receiving streams. Overall, the WWTPs did not contributed to the estrogenic activity of the receiving waters, but the livestock industry or wildlife may play an important role in the estrogenic contribution to river water.
Journal of Environmental Monitoring 11/2010; 13(1):101-9. · 1.99 Impact Factor
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ABSTRACT: A novel approach to the hydrophobic partitioning effect on efficient separation of protein such as BSA was demonstrated by the modification of hydrophobic pockets on the surface of silica-coated magnetic nanoparticles with various alkyl groups at various pH levels. The separation efficiency is strongly reflected and can be attained by controlling the size of the hydrophobic pocket and other factors such as the alkyl chain length, the salt concentration, and the pH levels. Furthermore, the adsorption constant (k(ad)) was calculated for the hydrophobic partitioning interaction between BSA and the hydrophobic pocket size at various pH levels.
Analytical Biochemistry 10/2010; 405(1):135-7. · 3.00 Impact Factor
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ABSTRACT: The aim of this article was to study the effects of land use change and water reuse options on an urban water cycle. A water cycle analysis was performed on the Goonja drainage basin, located in metropolitan Seoul, using the Aquacycle model. The chronological effects of urbanization were first assessed for the land uses of the Goonja drainage basin from 1975 to 2005, where the ratio of impervious areas ranged from 43% to 84%. Progressive urbanization was identified as leading to a decrease in evapotranspiration (29%), an increase in surface runoff (41%) and a decrease in groundwater recharge (74%), indicating a serious distortion of the water cycle. From a subsequent analysis of the water reuse options, such as rainwater use and wastewater reuse, it is concluded that wastewater reuse seemed to have an advantage over rainwater use for providing a consistent water supply throughout the year for a country like Korea, where the rainy season is concentrated during the summer monsoon.
Journal of Environmental Sciences 01/2010; 22(6):923-8. · 1.66 Impact Factor
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ABSTRACT: The removal efficiency of endocrine disrupting compounds from effluents using pilot scale sewage treatment processes, including various treatment technologies, such as membrane bioreactors (MBR), nanofiltration (NF) and reverse osmosis (RO) for the purpose of water reuse, were estimated and compared. The calculated estrogenic activity, expressed in ng-EEQ/l, based on the concentration detected by GC/MS, and relative potencies for each target compound were compared to those measured using the E-screen assay. The removal efficiencies for nonylphenol, was within the range of 55-83% in effluents. High removal efficiencies of approximately >70% based on the detection limits were obtained for bisphenol A, E1, EE2 and genistein with each treatment processes, with the exception of E1 ( approximately 64%) using the MBR process. The measured EEQ values for the effluents from the MBR, NF and RO processes also indicated low estrogenic activities of 0.65, 0.23 and 0.05 ng-EEQ/l, respectively. These were markedly reduced values compared with the value of 1.2 ng-EEQ/l in influent. Consequently, the removals of EDCs in terms of the EEQ value from the biological and chemical determinations were sufficiently achieved by the treatment process applied in this study, especially in the cases of the NF and RO treatments.
Chemosphere 05/2008; 71(8):1582-92. · 3.21 Impact Factor
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ABSTRACT: The complexation reaction between Cu and four targeted endocrine-disrupting compounds (EDCs)-17beta-estradiol (E2), 17alpha-ethynylestradiol (EE2), 4-octylphenol (OP), and bisphenol A (BPA)-was studied using the fluorescence quenching method, with the changed EDC forms evaluated for their estrogenic activities using an E-screen assay. The results of the E-screen showed no estrogenic activity of Cu, whereas results with the EDCs indicated high cell proliferation (decreasing order of induction: E2, EE2, OP, and BPA). The results of the fluorescence quenching response and FTIR (Fourier transformation infrared) strongly support the formation of Cu complexes on the -OH functional group of the targeted EDCs when Cu was spiked at concentrations between 10(-7) and 10(-4) M. The degree of complexation was in the following order: E2, EE2, OP, and BPA. The E-screen result for three of the EDCs, with the exception of BPA, was similar when estimating the effects of Cu on the estrogenic activities of the EDCs, which were significantly reduced at alpha = 0.05 with increasing Cu concentration. Consequently, the results of the complexation reaction and E-screen assay with the Cu-EDC mixtures indicated that Cu plays a significant role in the assessment of the estrogenic activities of EDCs in natural waters.
Environmental Toxicology and Chemistry 04/2008; 27(3):535-41. · 2.81 Impact Factor
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ABSTRACT: The objective of this study was to investigate the effect of dissolved organic ligands, such as EDTA, humic acids, hydrophobic and hydrophilic fractions of dissolved organic matter (DOM), on the growth of Pseudokirchneriella subcapitata in cultured media and natural lake waters. The growth of algae was gradually increased on the addition of dissolved organic ligands, but markedly declined at high concentrations, due to reduced bioavailable iron concentrations (e.g., Fe3+ and Fe'--inorganic ferric iron). The results demonstrated that the high growth rates of P. subcapitata were correlated with the hydrophobic, but not hydrophilic, DOM from five lakes, spiked under the nutrients-controlled conditions. This was attributed to the role of DOM in controlling the bioavailable iron due to complexation of Fe(III) with -COOH and -OH functional groups on the hydrophobic DOM. Therefore, the hydrophobic DOM, as chelating agent, is a biologically important component in the lake waters, which affects the algal growth by interacting with bioavailable iron in the lake water and can change the results of bioassay experiments.
Ecotoxicology and Environmental Safety 03/2008; 72(2):335-43. · 2.29 Impact Factor
