Browsing by Author "Kan, Lou-Sing"

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Direct Observation of Single Molecule Conformational Change of Tight-Turn Paperclip DNA Triplex in Solution
(2009-10-01)
Liu, Ching-Ping
;
Wey, Ming-Tsai
;
Chang, Chia-Ching
;
Kan, Lou-Sing
;
生物科技學系
DNA triplex modulates gene expression by forming stable conformation in physiological condition. However, it is not feasible to observe this unique molecular structure of large molecule with 54 oligodeoxynucleotides directly by conventional nuclear magnetic approach. In this study, we observed directly single molecular images of paperclip DNA triplexes formation in a buffer solution of pH 6.0 by atomic force microscopy (AFM). Meanwhile, a diffuse "tail" of unwound DNA was observed in pH 8.0 solution. This designable approach in visualizing the overall structures and shapes of oligo-DNAs at the single molecular level, by AFM, is applicable to other biopolymers as well.
Direct visualization of triplex DNA molecular dynamics by fluorescence resonance energy transfer and atomic force microscopy measurements
(2008-04-01)
Chang, Chia-Ching
;
Lin, Po-Yen
;
Chang, Chia-Seng
;
Kan, Lou-Sing
;
交大名義發表
Direct visualization of triplex DNA molecular dynamics by fluorescence resonance energy transfer and atomic force microscopy measurements
(2007-11-12)
Chang, Chia-Ching
;
Lin, Po-Yen
;
Chen, Yen-Fu
;
Chang, Chia-Seng
;
Kan, Lou-Sing
We have detected the dynamics of 17-mer DNA triplex dissociation mechanism at the molecular level. Fluorescence resonance energy transfer (FRET) was used as an indicator of intermolecular interaction in nanometer range, whereas atomic force microscopy (AFM) was employed to address single molecule with sub-angstrom precision. The maximum rupture force of DNA triplex was found at pH 4.65, consistent with macroscopic observations. These results indicated that the FRET together with an AFM detection system could be used to reveal the DNA triplex interaction in nanometer scale unambiguously. (c) 2007 American Institute of Physics.
Protein folding: An antagonistic reaction of spontaneous folding and diffusion limited aggregation in nature
(2007-12-01)
Chang, Chia-Ching
;
Kan, Lou-Sing
;
生物科技學系
;
Department of Biological Science and Technology
Protein folding may follow a spontaneous process or a reaction-path directed process, determined by various folding transition boundaries due to intrinsic properties of the protein. A general first-order-like state-transition model predicts that a protein might be trapped in an aggregated state when the folding path crosses the transition boundary. Both experimental study and molecular simulation indicated that protein within this particular transition region might involve intermolecular interactions. Therefore, a direct folding process may have been a combination of an antagonistic reaction of spontaneous folding and a diffusion limited aggregation. In this paper, the protein folding mechanism and the theoretical basis of time limited diffusion/aggregation process are elaborated. The application of auto-correlation function in time dependent biological studies is also discussed.
Self-assembled molecular magnets on patterned silicon substrates
(2006)
Chang, Chia-Ching
;
Sun, Kien-Wen
;
Lee, Shang-Fan
;
Kan, Lou-Sing
;
Kuan, Chieh-Hsiung
The paper reports the methods of preparing molecular magnets and pattering of the molecules on semiconductor surface. A highly magnetically aligned metallothionein containing Mn and Cd (Mn,Cd-MT-2) was first synthesized. Those molecules were then placed into nanopores prepared on silicon (001) surfaces using electron beam lithography and reactive ion etching techniques. We have observed self-assemble growth of those MT molecules on the patterned Si surface. The MT molecules have grown into rod or ring type nanostructures, depending on the patterned nanostructures on the surface. We also provide scanning electron microscopy (SEM) and atomic force microscopy (AFM) studied of those molecular nanostructures. This engineered molecule shows molecular magnetization and is biocompatible with conventional semiconductors. These features make Mn,Cd-MT-2 a good candidate for biological applications and sensing sources of new nano-devices.
Self-assembled molecular magnets on patterned silicon substrates: Bridging bio-molecules with nanoelectronics
(2007-04-01)
Chang, Chia-Ching
;
Sun, Kien Wen
;
Lee, Shang-Fan
;
Kan, Lou-Sing
;
生物科技學系
The paper reports the methods of preparing molecular magnets and patterning of the molecules on a semiconductor surface. A highly magnetically aligned metallothionein containing Mn and Cd (Mn,Cd-MT-2) is first synthesized, and the molecules are then placed into nanopores prepared on silicon (001) surfaces using electron beam lithography and reactive ion-etching techniques. We have observed the self-assemble growth of the NIT molecules on the patterned Si surface such that the NIT molecules have grown into rod or ring type three-dimensional nanostructures, depending on the patterned nanostructures on the surface. We also provide scanning electron microscopy, atomic force microscopy, and magnetic force microscope studies of the molecular nanostructures. This engineered molecule shows molecular magnetization and is biocompatible with conventional semiconductors. These features make Mn,Cd-MT-2 a good candidate for biological applications and sensing sources of new nanodevices. Using molecular self-assembly and topographical patterning of the semiconductor substrate, we can close the gap between bio-molecules and nanoelectronics built into the semiconductor chip. (c) 2006 Elsevier Ltd. All rights reserved.