2009.8
About Instruments Today No. 171
Single Molecule Detection
In Memory of Professor Wunshain Fann [ 下載 PDF ]
Jui-Hung Hsu, Huan-Cheng Chang
Single Molecule Studies of Fluorescent Nanodiamonds [ 下載 PDF ]
Yuen Yung Hui, Yi-Ren Chang, Huan-Cheng Chang
Fluorescent nanodiamond (FND) offers great potential for use as a novel diagnostic agent in biomedicine, because it is biocompatible, non-toxic, and shows no sign of photobleaching. The negatively charged nitrogen-vacancy defect center is an active component of FND. It absorbs light strongly at 560 nm and emits fluorescence efficiently from red to the near infrared region, well suited for bioimaging applications. In this article, we summarize the studies of FND by single molecule techniques and discuss its prospective applications in life sciences.
Application of Immobilized Single Molecular Fluorescence Resonance Energy Transfer (FRET) in Molecular Biology [ 下載 PDF ]
Wei-hau Chang
In recent years, single moleucle optical imaging and analysis has emerged as a powerful way to unfold the dyanmic and heterogeneous behavior of numerous biological systems. Among all single moleucle technique, singlemolecule fluorescence resonance fluorescence energy transfer (smFRET) spectroscopic imaging in an immobilized fashion is particulary suitable for following the interactions between nucleic acids and proteins to 1 nm resolution with time resolution ranging from 10 ns to second. Here, we describe the principle of smFRET and a simple version of total internal reflection instrumentation and provide a successful application to the study of RNA exit channel on a transcribing RNA polymerase II.
Ten Years of Single Molecule Spectroscopy—Instrumentation and Application to Conjugated Polymer Photophysics [ 下載 PDF ]
Li-Ling Yang, Hsin-Liang Chen, Ching-Yang Yuan, Tsong-Shin Lim, Yi-Fang Huang, Jun-Jih Liang, Jonathon David White
The last decade has seen the widespread development and application of single-molecule detection techniques, especially in the research of biomolecules and fluorescent polymers. Dr. Wunshain Fann played a key role in this area, developing sophisticated instruments for single molecule spectroscopy in order to understand and elucidate the underlying mechanisms of luminescent conjugated polymer photo-physics. Here we introduce this instrumentation and summarize the picture of conjugated polymers resulting from the research of Dr. Fann’s group.
The Application of Single Particle Tracking Technique in Single Molecule Analysis [ 下載 PDF ]
Yi-Ren Chang, Chi-Han Chiou, Yu-Yan Huang, Chia-Fu Chou
Comparing to ensemble measurement, single molecule analysis allows us to truly observe the interaction between single molecule pair, and provides more detailed statistical information of the static and dynamic behaviors of individual molecules. Single particle tracking is one of the most powerful techniques in single molecule study. In this article, we introduce a real-time single particle tracking system which provides automatic feedback tracking of a magnetic microsphere based on its bright field diffraction patterns. The axial resolution of this tracking system is less then 50 nm, limited by our current hardwares, and its response rate is 50 Hz. We demonstrated, using DNA tethering experiment combined with magnetic tweezers, our system provides the capability of measuring molecular interactions in single molecule level.
Single-Molecule Tethered Particle Motion in Biomedical Research [ 下載 PDF ]
Yen-Cheng Chen, Hsiu-Fang Fan, Hung-Wen Li
Tethered particle motion (TPM) method is a simple technique to study the protein-DNA interactions at the single molecule level. By directly imaging the Brownian motion of the polystyrene bead, which is tethered to the coverslip through a DNA molecule, TPM allows the real-time measurement of DNA length change during enzymatic processes. We developed a force TPM experiment to further improve the resolution of the measurement, to extend the DNA application range and to achieve a linear and predictable relation between DNA length and bead Brownian motion. This FTPM method has been used to study the motion of a DNA helicase, RecBCD, along individual duplex DNA molecules and provided insights on its protein-DNA interaction.
Detections of Fluorescent Molecules and Nanoparticles by Using Surface Plasmons in Metallic Nanostructures [ 下載 PDF ]
Wei-Kuo Chang, Fan-Gang Tseng, Pei-Kuen Wei
Localized surface plasmons in metallic structures can sensitively detect biomolecules and have very high potentials in the biomedical applications. In this text, we introduce our research of using silver nanostructures to enhance the detection of fluorescent molecules. Different shapes of nano structures were studied by the dark-field optical microscopy. Comparing with the triangular and rectangular structures, the rod-like structure has the best efficiency in the fluorescence enhancement. In addition, the localized plasmons generate optical traps that can increase the immobilization of nano-objects. Using theoretical simulations and the optical microscopy, we verified the trapping effect of gold nanoparticles in the metallic nanoholes.
Observation of Non-Controllable Photo-Physical and Photo-Chemical Reactions by Single Molecule Fluorescence Investigations [ 下載 PDF ]
Jui-Hung Hsu
Non-controllable rare events are easily being hidden, thus not easy to monitor. We report the observation of photophysical and photo-chemical reactions of DiI molecules by single molecule fluorescence experiments. By monitoring the polarization and PL lifetime information from individual emission photon, it is possible to distinguish the rare reactions, include photo-induced isomerization, and environmental induced triplet state quenching. Our results demonstrate that single molecule fluorescence measurement is a unique tool for non-controllable reactions.
Fabrication and Permeation Measurements of Barrier Coatings on Flexible Substrates [ 下載 PDF ]
Dong-Sing Wuu, Eddy Lay, Chia-Hsiang Liu, Gu-Hao Jhang, Tsai-Ning Chen
Under optimization of plasma-enhanced chemical vapor deposition conditions, the barrier coatings (silicon nitrite, SiNx 50 nm/silicon oxide, SiOx 50 nm) on polycarbonate (PC) substrates at 200 °C could reduce the water vapor transmission rate (WVTR) to 0.01 g/m2/day and oxygen transmission rate (OTR) to 0.1 g/m2/day, respectively (via the Mocon instruments). To further reduce the permeation rate, the organic film (parylene C) was introduced in the barrier coating structure as the smooth and defect-decoupled layer. From the calcium test, the WVTR of parylene/SiNx bilayer on the PC substrate can decrease to 2 × 10−4 g/m2/day under room temperature and 40% relative humidity environment. Finally, the four-pair parylene/SiNx structure can achieve a WVTR value of 7.41 × 10−6 g/m2/day.
Patterned Microlens-Array Films for Light Enhancement of Organic Light-Emitting Devices [ 下載 PDF ]
Kuan-Yu Chen, Hoang-Yan Lin, Jiun-Haw Lee, Mao-Kuo Wei
Conventionally, micro-structured films (e.g. microlens array films) are often applied to enhance light-extraction efficiency and increase luminance of organic light-emitting display. However, this approach was suffered from poor image quality due to stray rays caused by micro-structures. This trade-off between efficiency and image quality can be solved by our novel microlens array arrangement.
Characteristic Analysis for Multilayer ZnO Pyroelectric Sensors [ 下載 PDF ]
Chun-Ching Hsiao, Yuh-Chung Hu, Rwei-Ching Chang, Ching-Kong Chao
Thin-film ZnO pyroelectric sensors use the pyroelectric effect to convert temperature variation to corresponding electrical signal. The quality of ZnO films and the structural design of pyroelectric sensors are key factors to determine the responsivity of ZnO pyroelectric sensors. The mechanical properties testing of thin films, the twostep sputtering process, the stress analysis of multilayer, and the structural design of pyroelectric sensors are used to optimize thin-film ZnO pyroelectric sensors.
General Purpose TE Cooling Control System [ 下載 PDF ]
Chien-Hung Chen, Tai-Shan Liao, Mao-Chiao Weng, Chih-Wen Chen
We report the design of TE cooling control system with a cost effective, general purpose, and easily to integrate with other measurement system. The TE cooling control system consists of thermistor type temperature measurement circuits, current output control circuit based on PWM, and data display. The temperature resolution of our measurement system is 0.1 °C. Maximum output current can reach to 2 A. The temperature measurement and current output of the automatic feedback control system are achieved by the implementation of an analog and digital background balancing circuit. The article also introduces the system structure, design, and measurement results that it looks forward to providing those information for any applications in related industries.
