# Development of Aptamers for RNase Inactivation in Xtract-Free™ Sample Collection and Transport Medium

## TL;DR

Researchers developed DNA aptamers to inactivate RNase in a sample collection medium, preserving RNA integrity for easier and more effective genetic testing.

## Contribution

The study introduces novel anti-RNase DNA aptamers for RNA preservation in an extraction-free sample collection medium.

## Key findings

- Aptamers reduced RNase activity by 8800- to 11,200-fold, protecting viral RNA from digestion.
- Aptamers were selected using SELEX and validated via fluorometric and real-time RT-PCR methods.
- Integration of aptamers into XF medium shows potential for improving RNA quality in genomic analyses.

## Abstract

There is a significant need to develop new environmentally friendly, extraction-free sample collection mediums that can effectively preserve and protect genetic material for point-of-care and/or self-collection, home-collection, and mail-back testing. Systematic evolution of ligands by exponential enrichment (SELEX) was used to create anti-ribonuclease (RNase) deoxyribonucleic acid (DNA) aptamers against purified RNase A conjugated to paramagnetic carboxylated beads. Following eight rounds of SELEX carried out under various stringency conditions, e.g., selection using Xtract-Free™ (XF) specimen collection medium and elevated ambient temperature of 28 °C, a panel of five aptamers was chosen following bioinformatic analysis using next-generation sequencing. The efficacy of aptamer inactivation of RNase was assessed by monitoring ribonucleic acid (RNA) integrity via fluorometric and real-time RT-PCR analysis. Inclusion of aptamers in reaction incubations resulted in an 8800- to 11,200-fold reduction in RNase activity, i.e., digestion of viral RNA compared to control. Thus, anti-RNase aptamers integrated into XF collection medium as well as other commercial reagents and kits have great potential for ensuring quality intact RNA for subsequent genomic analyses.