COMPOSITIONS AND METHODS OF SELECTIVE NUCLEIC ACID ISOLATION
The invention relates to methods for isolating and/or identifying nucleic acids. The invention also provides kits for isolating and/or identifying nucleic acids.
1 . A method for isolating DNA and RNA from a biological sample comprising:
selectively binding DNA to a first solid phase by contacting the biological sample with the first solid phase under conditions which selectively bind DNA;
separating the first solid phase with the bound DNA from a first unbound portion of the biological sample;
isolating the DNA from the first solid phase; and
isolating RNA from the first unbound portion of the biological sample, wherein the isolating of the RNA from the first unbound portion of the biological sample comprises:
exposing the first unbound portion of the biological sample to a second solid phase under conditions which bind RNA to the second solid phase, wherein the conditions which bind RNA to the second solid phase comprise a neutral or acidic pH;
separating the second solid phase with bound RNA from a second unbound portion of the biological sample; and
isolating the RNA from the second solid phase.
2 . The method of claim 1 , wherein the isolating the DNA from the first solid phase comprises eluting the DNA.
3 . The method of claim 1 , wherein the isolating of the RNA from the second solid phase comprises eluting the RNA.
4 - 6 . (canceled)
7 . The method of claim 1 , wherein the conditions which selectively bind DNA comprise using a binding buffer comprising:
an alkaline pH; and
a large anion, wherein the large anion is at least as large as a bromide ion.
8 . The method of claim 7 , wherein the large anion is selected from at least one of picrate, tannate, tungstate, molybdate, perchlorate, and sulfosalicylate.
9 . The method of claim 7 , wherein the large anion is selected from at least one of trichloroacetate, tribromoacetate, thiocyanate, and nitrate.
10 . The method of claim 7 , wherein the large anion is selected from at least one of iodide and bromide.
11 . The method of claim 7 , wherein the alkaline pH is equal to, or above 8.0.
12 . The method of claim 7 , wherein the alkaline pH is equal to, or above 9.0.
13 . The method of claim 7 , wherein the alkaline pH is equal to, or above 10.0.
14 . A method of isolating nucleic acid from a biological sample comprising:
binding nucleic acid to a first solid phase by contacting the biological sample with the first solid phase under conditions which bind both RNA and DNA;
separating the first solid phase with bound nucleic acid from a first unbound portion of the biological sample;
eluting RNA from the first solid phase with bound nucleic acid under conditions which selectively bind DNA;
removing the first solid phase with bound DNA from a first eluate; and
isolating the DNA from the first solid phase.
15 . The method of claim 14 , wherein the isolating the DNA from the first solid phase comprises eluting the DNA from the first solid phase.
16 - 18 . (canceled)
19 . The method of claim 14 , wherein the conditions which selectively bind DNA comprise using a binding buffer comprising:
an alkaline pH; and
a large anion, wherein the large anion is at least as large as a bromide ion.
20 . The method of claim 19 , wherein the large anion is selected from at least one of picrate, tannate, tungstate, molybdate, perchlorate, and sulfosalicylate.
21 . The method of claim 19 , wherein the large anion is selected from at least one of trichloroacetate, tribromoacetate, thiocyanate, and nitrate.
22 . The method of claim 19 , wherein the large anion is selected from at least one of iodide and bromide.
23 . The method of claim 19 , wherein the alkaline pH is equal to, or above 8.0.
24 . The method of claim 19 , wherein the alkaline pH is equal to, or above 9.0.
25 . The method of claim 19 , wherein the alkaline pH is equal to, or above 10.0.
26 . The method of claim 14 , further comprising:
exposing the first eluate to a second solid phase under conditions which bind RNA to the second solid phase;
separating the second solid phase with the bound RNA from an unbound portion of the first eluate; and
isolating the RNA from the second solid phase.
27 . The method of claim 26 , wherein the isolating the RNA from the second solid phase comprises eluting the RNA.
28 - 30 . (canceled)
31 . The method of claim 26 , wherein the conditions which bind RNA to the second solid phase comprise a neutral or acidic pH.
32 . The method of claim 26 , wherein the conditions which selectively bind DNA comprise using a binding buffer comprising:
an alkaline pH; and
a large anion, wherein the large anion is at least as large as a bromide ion.
33 . The method of claim 32 , wherein the conditions which bind RNA to the second solid phase comprise a neutral or acidic pH.
34 - 35 . (canceled)
36 . A method of identifying nucleic acid in a biological sample comprising:
binding nucleic acid to a first solid phase by contacting the biological sample with the first solid phase under conditions which bind both DNA and RNA;
separating the first solid phase with bound nucleic acid from a first unbound portion of the biological sample;
eluting RNA from the first solid phase with bound nucleic acid under conditions which selectively bind DNA;
removing the first solid phase with bound DNA from a first eluate; and identifying the DNA bound to the first solid phase.
37 . The method claim 36 , wherein the identifying the DNA bound to the first solid phase comprises amplifying the DNA bound to the first solid phase.