Extraction of microRNAs from biological matrices with titanium dioxide nanofibers.

MicroRNAs (miRNAs) are small RNAs that bind to mRNA targets and regulate their translation. A functional study of miRNAs and exploration of their utility as disease markers require miRNA extraction from biological samples, which contain large amounts of interfering compounds for downstream RNA identification and quantification. The most common extraction methods employ silica columns or the TRIzol reagent but give out low recovery for small RNAs probably due to their short strand lengths. Herein, we fabricated the titanium dioxide nanofibers using electrospinning to facilitate miRNA extraction and developed the optimal buffer conditions to improve miRNA recovery from biological matrices of cell lysate and serum. We found that our TiO2 fibers could obtain a recovery of 18.0 ± 3.6% for miRNA fibers while carrying out the extraction in the more complex medium of cell lysate, much higher than the 0.02 ± 0.0001% recovery from the commercial kit. The much improved extraction of miRNAs from our fibers could be originated from the strong coordination between TiO2 and RNA's phosphate backbone. In addition, the binding, washing, and elution buffers judiciously developed in the present study can achieve selective extraction of small RNA shorter than 500 nucleotides in length. Our results demonstrate that TiO2 nanofibers can work as a valuable tool for extraction of miRNAs from biological samples with high recovery. Graphical abstract Schematic for extraction of small RNAs using TiO2 nanofibers.