Methods and compositions for extracting nucleic acids using ferric oxide particles

A method of generating a sample of extracted microRNAs from an initial biological sample, the method comprising:

• (a) contacting the initial biological sample comprising microRNAs with proteinase K at a temperature in a range of from 47° C. to 53° C. for a period of time in a range of from 10 to 40 minutes, to degrade proteins present in the sample, thereby producing a proteinase K treated sample;
• (b) contacting the proteinase K treated sample with ferric oxide particles under acidic conditions to induce binding between the ferric oxide particles and the microRNAs;
• (c) magnetically separating the microRNA bound ferric oxide particles from the proteinase K treated sample;
• (d) contacting the microRNA bound ferric oxide particles with an alkaline elution buffer to release the microRNAs from the ferric oxide particles into the alkaline elution buffer, thereby generating an alkaline microRNAs sample;
• and
• (e) magnetically separating the ferric oxide particles from the alkaline microRNA sample,
• to generate a sample of extracted microRNAs.