Disclosed herein are method for separating, amplifying, or detecting a nucleic acid from a sample may comprise contacting a sample lysate with a plurality of buoyant, inorganic, nucleic-acid-capture microspheres. The nucleic-acid-capture microspheres may comprise unicellular hollow microspheres having a diameter between 5 and 300 μm and/or a true particle density between 0.05 and 0.60 grams/cm3. The microspheres may comprise hollow soda-lime-borosilicate microspheres. In some embodiments, the microspheres comprises hollow soda-lime-borosilicate microspheres surrounded by an amorphous silica shell. Also disclosed are kits for performing the methods.