UC Riverside

Nucleic acids are biomolecules found in all living things in great abundance and are most commonly found in cells. The two principal nucleic acids are DNA and RNA. DNA’s primary function is to encode genetic information for amino acid sequences that make up proteins that are important in cell functions. RNA has various roles that include regulation and expression of genes.

MicroRNAs (miRNAs) are small RNAs, which range between 20 to 25 nucleotides, that bind to mRNA targets and regulate their translation. Circulating miRNAs are bound to various carriers, including nucleoprotein complexes, lipoproteins, exosomes and microvesicles. The carriers protect the miRNAs from degradation and are able to provide transportation to malignant cells where miRNAs may contribute to tumor progression and metastasis. 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.

Aptamers are short, single stranded oligonucleotides, usually around 30 to 50 nucleotides in length that bind to their targets with high affinity and specificity and are comparable to antibodies. Aptamers are discovered through a process known as systematic evolution of ligands by exponential enrichment (SELEX) and necessitates recovery of the ssDNA. An efficient recovery of ssDNA aptamers in SELEX is required to develop high affinity DNA aptamers capable of selectively binding a target molecule.

The most common extraction methods employ either silica columns or TRIzol reagent, but these approaches afford low recovery for small RNAs, possibly due to their short strand lengths. We fabricated the titanium dioxide nanofibers using electrospinning to facilitate DNA and miRNA extraction and developed the optimal buffer conditions to improve DNA and miRNA recovery from biological buffers, cell lysate, and serum. Improving the recovery of nucleic acids (NA) could result from the strong coordination between TiO2 and NA’s phosphate backbone. Our results demonstrated that TiO2 nanofibers can work as a valuable tool for extraction of NA from complex biological matrices with high recovery.