Method and apparatus for imaging biological samples with MALDI MS
First Claim
1. A method of analyzing the spacial arrangement of specific molecules within a sample, comprising:
- (a) generating a test specimen including a thin sample layer with an energy absorbant matrix;
(b) striking the test specimen with a laser beam such that a predetermined first laser spot on the test specimen releases first sample molecules;
(c) measuring the molecular atomic mass of the released first sample molecules over a range of atomic masses;
(d) moving the test specimen relative to the laser beam a predetermined linear distance functionally related to a size of the predetermined first laser spot;
(e) thereafter striking the test specimen with the laser beam such that a predetermined second laser spot on the test specimen releases second sample molecules;
(f) measuring the molecular atomic mass of the released second sample molecules over a range of atomic masses; and
(g) analyzing an atomic mass window of interest within the range of atomic masses to determine the spacial arrangement of specific molecules within the sample.
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Accused Products
Abstract
MALDI MS has been used to generate images of samples in one or more m/z pictures, providing the capability of mapping concentrations of specific molecules in X,Y coordinates of the original sample. For sections of mammalian tissue, for example, this can be accomplished in two ways. First, tissue slices can be directly analyzed after thorough drying and application of a thin coating of matrix by electrospray. Second, imprints of the tissue can be analyzed by blotting the dry tissue sections on specially prepared targets, e.g., C-18 (10 μm dia.) beads. Peptides and small proteins bind to the C-18 and create a positive imprint of the tissue which can be imaged by MALDI MS after application of matrix. Such images can be displayed in individual m/z values as a selected ion image which would localize individual compounds in the tissue, as summed ion images, or as a total ion image which would be analogous to a photomicrograph. This imaging process may also be applied to separation techniques where a physical track or other X,Y deposition process is utilized, for example, in the CE/MALDI MS combination where a track is deposited on a membrane target.
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Citations
27 Claims
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1. A method of analyzing the spacial arrangement of specific molecules within a sample, comprising:
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(a) generating a test specimen including a thin sample layer with an energy absorbant matrix; (b) striking the test specimen with a laser beam such that a predetermined first laser spot on the test specimen releases first sample molecules; (c) measuring the molecular atomic mass of the released first sample molecules over a range of atomic masses; (d) moving the test specimen relative to the laser beam a predetermined linear distance functionally related to a size of the predetermined first laser spot; (e) thereafter striking the test specimen with the laser beam such that a predetermined second laser spot on the test specimen releases second sample molecules; (f) measuring the molecular atomic mass of the released second sample molecules over a range of atomic masses; and (g) analyzing an atomic mass window of interest within the range of atomic masses to determine the spacial arrangement of specific molecules within the sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. The method of analyzing a test sample, comprising:
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(a) obtaining a sample solution including test sample molecules of interest; (b) passing the sample solution through a capillary tube and depositing the sample solution in a linear track on an electrically-conductive target plate by capillary electrophoresis; (c) drying the sample solution while in the linear track on the target plate; (d) striking the dried linear track with a laser beam such that the linear track releases molecules of interest; (e) measuring the molecular atomic mass of the released molecules of interest over a range of atomic masses; and (f) analyzing the molecular atomic masses as a function of time indicative of the position of the molecules of interest along the linear track to analyze the test sample. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. Apparatus for analyzing a test sample containing molecules of interest, comprising:
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a test specimen containing sample molecules of interest and an energy-absorbant matrix; a laser source for sequentially striking the test specimen with a laser beam at a plurality of laser spots on the test specimen for sequentially releasing sample molecules from each laser spot; a moving mechanism for sequentially moving the test specimen relative to the laser beam a predetermined linear distance functionally related to the size of the laser spots prior and subsequent to the movement; a mass analyzer for measuring the atomic mass of the released sample molecules over a range of atomic masses; a computer for receiving atomic mass data from the mass analyzer; and a display for depicting atomic mass within an atomic mass window of interest as a function of individual laser spots on the test specimen. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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Specification