Single molecule detection or quantification using DNA nanotechnology
The present invention relates to a method and a DNA nanostructure for detecting a target structure. In particular, the present invention relates to a DNA nanostructure, which ensures a preferably linear dependence on the number of marker molecules and the measurement signal regardless of the physical arrangement of a plurality of such DNA nanostructures by virtue of the skilled selection of the shape of the DNA nanostructure and the placement of the marker molecules attached to it. The invention additionally relates to the use of said DNA nanostructures and other nanoreporters, preferably in combination with adapters which bind specifically to target molecules, in a method for quantifying a plurality of target molecules, preferably in a simultaneous manner, using a multiplex method.
1. A method for the detection of a target structure, comprising:
a) forming an identification structure, comprising:
(i) the target structure, and
(ii) at least two 3D DNA nanostructures, wherein the at least two 3D DNA nanostructures are separate and independent from each other, wherein each of the 3D DNA nanostructures comprises one or more inwardly disposed fluorescence dye molecules, wherein each of the 3D DNA nanostructures specifically binds to a different portion of the target structure, and wherein the 3D DNA nanostructures are bound to regions of the target structure that are pairwise different; and
b) detecting the target structure by measuring at least one fluorescence signal, wherein the 3D DNA nanostructures and parameters of fluorescence measurement are selected such that the at least one measured fluorescence signal of the identification structure a) is distinguishable from the fluorescence signal of each of the at least two isolated 3D DNA nanostructures, when these are not bound in the identification structure.
2. The method of claim 1 , wherein the identification structure is bound to a carrier or wherein the method further comprises the step of binding the formed identification structure to a carrier.
3. The method of claim 2 , wherein a bond or the binding of the identification structure to the carrier is mediated or is being mediated via the target structure.
4. The method of claim 3 , wherein the target structure is bound or is being bound to the carrier, wherein the bond or binding is mediated by a carrier adapter that specifically binds or is bound to the target structure.
5. The method of claim 1 , wherein the specific binding of at least one of the 3D DNA nanostructures is mediated by a target adapter assigned to a corresponding 3D DNA nanostructure, wherein the target adapter or each of the target adapters is designed to bind to the respective DNA nanostructure and to the respective region(s) of the target structure.
6. The method of claim 1 , wherein the method is further additionally suited for the detection of one or more further target structures that are different from each other, wherein the different target structures are pairwise different, and wherein the method further comprises:
c) for each of the one or more further target structures that are different from each other: forming a respectively assigned identification structure, wherein each of the further identification structures comprises:
(i) the further target structure that was assigned, and
(ii) at least two 3D DNA nanostructures, wherein each of the at least two 3D DNA nanostructures comprises one or more inwardly disposed fluorescence dye molecules and wherein each of the at least two 3D DNA nanostructures is specifically bound to the respective further target structure, and wherein the at least two 3D DNA nanostructures are bound to regions of the respective target structure that are pairwise different;
and wherein step b) further comprises:
d) detecting the one or more further target structures by measuring the at least one fluorescence signal,
wherein all 3D DNA nanostructures and the parameters of fluorescence measurement are selected such that the at least one measured fluorescence signal of the identification structures formed in a) and c) is distinguishable from the fluorescence signal of all isolated 3D DNA nanostructures, when these are not bound in one of the identification structures, and that the measured fluorescence signals of all formed identification structures are pairwise distinguishable from each other.
7. The method of claim 6 , wherein each of the different target structures is present multiple times and the method comprises the multiple detection of one or more of the different target structures.
8. The method of claim 6 , wherein measuring at least one fluorescence signal comprises:
e) creating a data set, which contains data of fluorescence signals emitted by a section of a sample by using a fluorescence microscope;
and wherein the detection of the target structure comprises:
f) identifying one or more of the datums contained in the data set, which represents the fluorescence signal of the identification structure.
9. The method of claim 8 , wherein the fluorescence signals of the identification structures formed for the individual different target structures differ from the fluorescence signal of all isolated 3D DNA nanostructures, when these are not bound in one of the identification structures, and the fluorescence signals of the identification structures which were formed for the individual different target structures are pairwise different, in that the corresponding fluorescence signals comprise a distinguishably different combination of color and/or intensity information.
10. The method of claim 9 , wherein in the 3D DNA nanostructures k intensity levels distinguishable from each other and/or m color levels distinguishable from each other are used, wherein the respective overlap of adjacent distributions is lower than 30%, and wherein k>2 and m>2.
11. The method of claim 10 , wherein each of the k intensity levels is formed by intensity distribution and wherein the k intensity distributions are distinguishable from each other.
12. The method of claim 10 , wherein each of the k intensity levels is formed by intensity distribution and wherein the k intensity distributions are statistically distinguishable from each other.
13. The method of claim 10 , wherein the m color distributions are distinguishable from each other.
14. The method of claim 10 , wherein the m color distributions are statistically distinguishable from each other.
15. The method of claim 8 , wherein the identifying in step f) comprises the following steps:
f1) reading out a color and/or an intensity information of a datum and/or image element; and
f2) comparing the color and/or intensity information of the datum and/or image element with a color and/or intensity information, being representative for the identification structure.
16. The method of claim 8 , wherein using a fluorescence microscope comprises using a fluorescence microscope in epifluorescence, TIRF, lightsheet and/or confocal microscopy.
17. The method of claim 1 , wherein measuring at least one fluorescence signal comprises:
e) creating a data set, which contains data of fluorescence signals emitted by a section of a sample by using a fluorescence microscope;
and wherein the detection of the target structure comprises:
f) identifying one or more of the datums contained in the data set, which represent(s) the fluorescence signal of the identification structures.
18. The method of claim 17 , wherein the identifying in step f) comprises the following steps:
f1) reading out a color and/or an intensity information of a datum and/or image element; and
f2) comparing the color and/or intensity information of the datum and/or image element with a color and/or intensity information, being representative for the identification structure.
19. The method of claim 17 , wherein using a fluorescence microscope comprises using a fluorescence microscope in epifluorescence, TIRF, lightsheet and/or confocal microscopy.