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San, Boi Hoa,Moh, Sang Hyun,Kim, Kyeong Kyu The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.5
<P>Protein shells have been used as nano-platforms for the synthesis of metallic nanoparticles for their biomedical and biocatalytic applications. However, it is challenging to maximize the catalytic activity of nanoparticles encapsulated by protein shells, as little research exists regarding their effect on the catalytic activities or physicochemical properties of nanoparticles. In this study, we used the following three proteins to synthesize platinum nanoparticles: aminopeptidase PepA, serine endoprotease DegP, and Clp protease. We then compared the catalytic properties of these protein-shelled platinum nanoparticles as scavengers of reactive oxygen species. These protein-shelled platinum nanoparticles displayed the catalase- and superoxide dismutase-like activities by quenching H<SUB>2</SUB>O<SUB>2</SUB> and O<SUB>2</SUB><SUP>−</SUP>, respectively. However, the resulting particle's size and activity depended on the particular protein shell. These results proved that the catalytic activity of protein-shelled platinum nanoparticles is greatly affected by the physicochemical properties of their protein shells. Collectively, current study indicates that protein shells are important determinants for the physical and catalytic properties of platinum nanoparticles and it is necessary to screen protein shells to optimize their functionality. Furthermore, considering the reduced cell toxicity of protein-shelled platinum nanoparticles compared to those synthesized by chemical stabilizers, it is suggested that they can serve as an antioxidant for biomedical purposes.</P> <P>Graphic Abstract</P><P>Platinum nanoparticles synthesized in PepA, DegP or ClpP protein shells displayed catalase- and superoxide dismutase-like activities, and the role of encapsulating proteins in their synthetic process and catalytic function was demonstrated. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1jm14581a'> </P>
Radiofrequency treatment enhances the catalytic function of an immobilized nanobiohybrid catalyst
San, Boi Hoa,Ha, Eun-Ju,Paik, Hyun-jong,Kim, Kyeong Kyu The Royal Society of Chemistry 2014 Nanoscale Vol.6 No.11
<▼1><P>A new strategy to enhance the functionality of biocatalysts has been demonstrated by combining three processes with enzymes: integration with inorganic nanoparticles, immobilization on the hydrogel, and radiofrequency current treatment.</P></▼1><▼2><P>Biocatalysis, the use of enzymes in chemical transformation, has undergone intensive development for a wide range of applications. As such, maximizing the functionality of enzymes for biocatalysis is a major priority to enable industrial use. To date, many innovative technologies have been developed to address the future demand of enzymes for these purposes, but maximizing the catalytic activity of enzymes remains a challenge. In this study, we demonstrated that the functionality of a nanobiocatalyst could be enhanced by combining immobilization and radiofrequency (RF) treatment. Aminopeptidase PepA-encapsulating 2 nm platinum nanoparticles (PepA–PtNPs) with the catalytic activities of hydrolysis and hydrogenation were employed as multifunctional nanobiocatalysts. Immobilizing the nanobiocatalysts in a hydrogel using metal chelation significantly enhanced their functionalities, including catalytic power, thermal-stability, pH tolerance, organic solvent tolerance, and reusability. Most importantly, RF treatment of the hydrogel-immobilized PepA–PtNPs increased their catalytic power by 2.5 fold greater than the immobilized PepA. Our findings indicate that the catalytic activities and functionalities of PepA–PtNPs are greatly enhanced by the combination of hydrogel-immobilization and RF treatment. Based on our findings, we propose that RF treatment of nanobiohybrid catalysts immobilized on the bulk hydrogel represents a new strategy for achieving efficient biocatalysis.</P></▼2>
Investigation of the heating properties of platinum nanoparticles under a radiofrequency current
San, Boi Hoa,Moh, Sang Hyun,Kim, Kyeong Kyu Informa UK, Ltd. 2013 International journal of hyperthermia Vol.29 No.2
<P><I>Purpose</I>: For the potential application of platinum nanoparticles (PtNPs) in hyperthermia therapy, the heating efficiency of PtNPs in the presence of radiofrequency (RF) current generated by a capacitive electric transfer (CET) system was compared with that of gold nanoparticles (AuNPs).</P><P><I>Materials and methods</I>: PtNPs and AuNPs synthesised by citrate capping (5 nm) were exposed to an RF current of 0.35 ± 0.05 MHz in a CET system. The temperature of the solution containing various concentrations of platinum or gold NPs was monitored for 5 min at various power ranges.</P><P><I>Results</I>: When both NP solutions were exposed to an RF field at a fixed power, the temperature of the NP solution increased continuously over the 5 min of measurement. In contrast, the NP-free solutions did not show any temperature change. Both PtNPs and AuNPs can be heated in a concentration- and power-dependent manner. However, PtNPs showed a higher efficiency in generating heat compared with AuNPs in both water and the physiological buffer.</P><P><I>Conclusions</I>: The heat generating efficiency of 5-nm PtNPs was about 50% higher than that of AuNPs when they were exposed to electric current through RF. This result suggests that PtNPs are promising nanomaterials for RF-induced hyperthermia therapy.</P>
Combining Protein-Shelled Platinum Nanoparticles with Graphene to Build a Bionanohybrid Capacitor
San, Boi Hoa,Kim, Jang Ah,Kulkarni, Atul,Moh, Sang Hyun,Dugasani, Sreekantha Reddy,Subramani, Vinod Kumar,Thorat, Nanasaheb D.,Lee, Hyun Ho,Park, Sung Ha,Kim, Taesung,Kim, Kyeong Kyu American Chemical Society 2014 ACS NANO Vol.8 No.12
<P>The electronic properties of biomolecules and their hybrids with inorganic materials can be utilized for the fabrication of nanoelectronic devices. Here, we report the charge transport behavior of protein-shelled inorganic nanoparticles combined with graphene and demonstrate their possible application as a bionanohybrid capacitor. The conductivity of PepA, a bacterial aminopeptidase used as a protein shell (PS), and the platinum nanoparticles (PtNPs) encapsulated by PepA was measured using a field effect transistor (FET) and a graphene-based FET (GFET). Furthermore, we confirmed that the electronic properties of PepA-PtNPs were controlled by varying the size of the PtNPs. The use of two poly(methyl methacrylate) (PMMA)-coated graphene layers separated by PepA-PtNPs enabled us to build a bionanohybrid capacitor with tunable properties. The combination of bioinorganic nanohybrids with graphene is regarded as the cornerstone for developing flexible and biocompatible bionanoelectronic devices that can be integrated into bioelectric circuits for biomedical purposes.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-12/nn503178t/production/images/medium/nn-2014-03178t_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn503178t'>ACS Electronic Supporting Info</A></P>
Bioinorganic Nanohybrid Catalyst for Multistep Synthesis of Acetaminophen, an Analgesic
San, Boi Hoa,Ravichandran, Subramaniyam,Park, Kwang-su,Subramani, Vinod Kumar,Kim, Kyeong Kyu American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.44
<P>A bioinorganic nanohybrid catalyst was synthesized by combining esterase with a platinum nanoparticle (PtNP). The combination of two catalysts resulted in enhanced catalytic activities, esterase hydrolysis, and hydrogenation in PtNPs, as compared to each catalyst alone. This hybrid catalyst can be successfully used in the multistep synthesis of acetaminophen (paracetamol), an analgesic and antipyretic drug, in a one-pot reaction with high yield and efficacy within a short time, demonstrating that the nanobiohybrid catalyst offers advantages in the synthesis of fine chemicals in industrial applications.</P>
San, Boi Hoa,Kim, Sungsu,Moh, Sang Hyun,Lee, Hyunjoo,Jung, Duk‐,Young,Kim, Kyeong Kyu WILEY‐VCH Verlag 2011 Angewandte Chemie Vol.123 No.50
<P><B>Außen Bio, innen Nano</B>: Durch Einkapselung von Platin‐Nanopartikeln in einer bakteriellen Aminopeptidase resultiert ein neuartiges Hybridkonstrukt, das Platin‐katalysierte Hydrierung und Peptidase‐katalysierte Hydrolyse zu Mehrstufensynthesen kombinieren kann (siehe Bild). Die Übertragung dieses bioanorganischen Einkapselungskonzepts auf zahlreiche Enzyme und anorganische Materialien kann zu neuartigen multifunktionalen Materialien führen.</P>
Ramzi, Mdouki,Bois, Gerard,Abderrahmane, Gahmousse Korean Society for Fluid machinery 2011 International journal of fluid machinery and syste Vol.4 No.1
With the aim to increase blade loadings and stable operating range in highly loaded compressors, this article has been conducted to explore, through a numerical parametric study, the potential of passive control using slotted bladings in cascade configurations. The objective of this numerical investigation is to analyze the influence of location, width and slope of the slots and therefore identify the optimal configuration. The approach is based on two dimensional cascade geometry, low speed regime, steady state and turbulent RANS model. The results show the efficiency of this passive technique to delay separation and enhance aerodynamic performances of the compressor cascade. A maximum of 28.3% reduction in loss coefficient have been reached, the flow turning is increased with approximately $5^0$ and high loading over a wide range of angle of attack have been obtained for the optimized control parameter.
( Thuy Duong Nguyen ),( Boi An Tran ),( Ke Oanh Vu ),( Anh Son Nguyen ),( Anh Truc Trinh ),( Gia Vu Pham ),( Thi Xuan Hang To ),( Thanh Thao Phan ) 한국부식방식학회(구 한국부식학회) 2020 Corrosion Science and Technology Vol.19 No.2
This work examined the corrosion protection performance of benzoate loaded hydrotalcite/graphene oxide (HT/GO-BZ) for carbon steel. HT/GO-BZ was fabricated by the co-precipitation method and characterized by infrared spectroscopy, X-ray diffraction, and scanning electronic microscopy. The corrosion inhibition action of HT/GO-BZ on carbon steel in 0.1 M NaCl solution was evaluated by electrochemical measurements. The benzoate content in HT/GO-BZ was determined by UV-Vis spectroscopy. Subsequently, the effect of HT/GO-BZ on the corrosion resistance of the water-based epoxy coating was investigated by the salt spray test. The obtained results demonstrated the intercalation of benzoate and GO in the hydrotalcite structure. The benzoate content in HT/GO-BZ was about 16%. The polarization curves of the carbon steel electrode revealed anodic corrosion inhibition activity of HT/GO-BZ and the inhibition efficiency was about 95.2% at a concentration of 3g/L. The GO present in HT/GO-BZ enhanced the inhibition effect of HT-BZ. The presence of HT/GO-BZ improved the corrosion resistance of the waterborne epoxy coating.