Compositions and methods of selective nucleic acid isolation

Abstract

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.