Method for optically manipulating polymer filaments
First Claim
1. A method of preparing a polymer filament for microscopic examination in an extended condition, comprisingcoupling one end of the filament to a particle in the size range of about 10 nm to 10 gm,suspending the filament and attached particle in a fluid film in a chamber,securing the other end of the filament in the chamber,capturing the particle in an optical trap produced by directing a beam of divergent, coherent light through a collimating lens and directing the resulting collimated beam through a high-numerical aperture objective lens, where the collimating lens is positioned to (a) shift the angle by which the collimated beam produced by directing the divergent beam through the collimating lens is directed against the objective lens, thereby to shift the position of said optical trap produced by directing the collimated beam through the objective lens, and (b) maintain the position of the collimated beam substantially fixed in the plane of the objective lens, so that the beam fills the lens at any beam angle and the light intensity of the trap is substantially independent of position, andmoving the source of the divergent light, to produce a corresponding movement of the optical trap, until the filament is in an extended condition.
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Accused Products
Abstract
Method and apparatus for manipulating a microscopic particle by single-beam gradient optical trapping, using an optical beam whose trapping force is substantially independent of position within a view field. The apparatus may be used to extend a polymer filament, and to fix the extended filament at a selected stretching force. When applied to nucleic acid filament, the method may be employed for genomic DNA mapping of filaments up to several megabasepairs in size. The method may also be used for studying the interaction of enzymes or ribosomes with extended DNA in real time.
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Citations
16 Claims
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1. A method of preparing a polymer filament for microscopic examination in an extended condition, comprising
coupling one end of the filament to a particle in the size range of about 10 nm to 10 gm, suspending the filament and attached particle in a fluid film in a chamber, securing the other end of the filament in the chamber, capturing the particle in an optical trap produced by directing a beam of divergent, coherent light through a collimating lens and directing the resulting collimated beam through a high-numerical aperture objective lens, where the collimating lens is positioned to (a) shift the angle by which the collimated beam produced by directing the divergent beam through the collimating lens is directed against the objective lens, thereby to shift the position of said optical trap produced by directing the collimated beam through the objective lens, and (b) maintain the position of the collimated beam substantially fixed in the plane of the objective lens, so that the beam fills the lens at any beam angle and the light intensity of the trap is substantially independent of position, and moving the source of the divergent light, to produce a corresponding movement of the optical trap, until the filament is in an extended condition.
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9. A method of nucleic acid filament sample preparation, for examining a filament in an extended condition within a chamber, comprising
coupling one end of the filament to a particle, with the particle and attached filament suspended in a thin film of aqueous medium, and the opposite end of the filament anchored in a chamber, capturing the particle in an optical beam trap, manipulating the position of the particle relative to the other end of the filament, to place the filament in the film in an extended condition, and fixing the filament in an extended condition.
Specification