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[주간세미나] 2015년 11월 9일
관리자 2015-11-04

<최우석 교수 Lab.>

* 발표자 : 김병훈

* 제목 : Harnessing a Designer Protein/DNA Biotemplate for Patterned Biomineralization of TiO2 Nanocrystals in 2D Array

* 내용 : Patterned biomineralization of nanosized single-crystalline rutile TiO2 was first achieved without calcination step by using a designer protein/DNA conjugated biotemplate, where nanotiled DNA nanostructure was used as a scaffold and LacI-STB1 protein as a nucleation trigger. lacO duplex embedded double-crossover DNA nanostructure (lacO-embedded DNA or LED) was self-assembled using two types of DNA tile via the base pairings of uniquely programmed complementary sticky end sequences. The formation of a designer biotemplate comprising LED and LacI-STB1 protein was enabled by harnessing intrinsic interaction between lacO duplex on LED and DNA binding domain at N-terminus of LacI-STB1. Subsequently, the designer biotemplate was immersed in TiBALDH precursor solution to initiate biomineralization of TiO2 in 2D array on the biotemplate. Biomineralized TiO2 was in nanorod shape, as its preferential growth was in direction of closely positioned LacI-STB1 with ~6 nm gap. Single-crystalline rutile TiO2 nanorod was obtained regardless of whether the biotemplate was in free solution or on silica substrate, with large-area patterning realized in the presence of silica substrate.

* 발표자 : Saad Salman

* 제목 : Size-tunable Core-shell TiO2 using Insoluble Denatured lysozyme-phosphate ion Complex

* 내용 : Biomineralization provides an environmentally benign alternative to the conventional methods by enabling synthesis of various inorganic materials at ambient conditions with the use of diverse biomolecules. Proteins are especially attractive since they provide rigid and stable biotemplates in varying conformations conducive to controlling properties (e.g. size, morphology, crystallinity) of inorganic material during biomineralization reactions. In this study, we used biotemplates derived from native or heat-denatured lysozyme to trigger TiO2 biomineralization and investigated the effects of protein and/or biotemplate structure on the size and morphology of the mineralized TiO2. Native lysozyme was found to give soluble biotemplates of ca. 4 nm in size regardless of the presence of phosphate ions. However, denatured lysozyme in the absence of phosphate ions gave soluble biotemplate. TiO2 mineralization using these soluble biotemplate induced TiO2 particles of diameters 80-100 nm interconnected each other. In contrast, denatured lysozyme in the presence of phosphate ion produced insoluble biotemplates capable of mineralizing individual TiO2 particles in core-shell structure. Moreover, the size of the insoluble biotemplate and the resulting mineralized TiO2 was adjustable by controlling molar ratio of phosphate ion to lysozyme and reaction temperature. The presence of sufficient phosphate ion on denatured lysozyme solution was essential factor to insoluble biotemplate but it could not affect size of the biotemplate. However, the reaction temperature affected interaction between denatured lysozyme and phosphate ion and rising of temperature resulted in increase of diameter of the biotemplate and the resulting mineralized TiO2. These biomineralized core-shell TiO2 particles are proposed for battery and water-splitting applications.
[주간세미나] 2015년 11월 2일
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