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Why we conduct single molecule or what single
molecule can tell us?
In contrast with ensemble methods, single molecule experiments provide information on distributions and time trajectories of observables that would otherwise be hidden
A Single-Molecule Study of RNA Catalysis and Folding
The Nobel Prize in Physics 1997
"for development of methods to cool and trap atoms with
laser light"
•methods of manipulating and modifying single particles
What is single
molecule biophysics?
在单分子水平上对生物分子行为（包括构 象变化、相互作用、相互识别等）的实时 ﹑动态检测以及在此基础上的操纵﹑调控 等，是分子生物物理学的自然延伸和必然 趋势。生物单分子研究已成为21世纪生命 科学领域的一个重点研究方向，在生命科 学领域有着广泛的应用前景
How to increase S/N?
a small excitation volume, to
reduce the background
high-efficiency collection optics
detectors with high quantum efficiency and low dark noise careful elimination of background fluorescence:
solvent, optics, detection method et al.
Techniques to study the single molecule
Laser Scanning Confocal Microscopy (LSCM) Total Internal Reflection Fluorescence Microscopy (TIRFM)
single molecule methods
Sensitive or ultrasensitive
sensitivity
Genesis of noise?
The photons detected from single molecules must exceed the background noise that originates from Raman and Rayleigh scattering and from fluorescence as a result of impurities in the solvent, glass coverslips, and optical components, and from dark current in the detector.
Near field Scanning Optical Microscopy (NSOM or SNOM)
Scanning Probe Microscopy (SPM):
Scanning Tunneling Microscope STM
Atom Force Microscope ( AFM )
Optical tweezer/ optical trap OP or OT
A Single-Molecule Study of RNA Catalysis and Folding
•single molecules in diverse environments such as liquids, solids, membranes, surfaces, and polymers
•single atoms and nanoparticles
•all kinds of ultrasensitive detection techniques such as spectroscopies and microscopies
Steven Chu USA
Claude Cohen- William D.
Tannoudji
Phillips
France
USA
光束密糖 Molasses
朱棣ห้องสมุดไป่ตู้(江苏太仓)
在获得诺贝尔奖的第二天， 他骑着自行车，朝着目标往 山路上攀爬，达到了目的地。 这种攀登高峰的踏实感受: 也只有在努力过之后，才能 真切地感受到
What is single molecule biophysics? Why we conduct single molecule or what
single molecule can tell us?
How to study the single molecules?
Single Molecules provides a broad overview of current methods and techniques, recent applications and shortcomings of present techniques in the field. It covers all aspects of single molecule investigations in chemistry, physics, and life sciences:
Single molecule 23294
As of 2003 Single Molecules ceased publication and the articles are incorporated in ChemPhysChem
Impetus to single molecule
less faster
