Systematic Evolution of Ligands by Exponential Enrichment Selection of Specific Aptamer for Sensing of Methamphetamine

Abstract

Worldwide epidemic addiction to methamphetamine (METH) continues to grow increasingly. Neurotoxicity of METH is very significant, which can irreversibly impact the central nervous system (CNS). However, no effective pharmacotherapy is available to preserve its adverse impacts. Fast and cost-effective sensing/detection of METH may help health system to control its abuse, while such a sensing system is not available yet, mainly due to lack of suitable METH-sensing probe. Aptamers, as DNA/RNA oligonucleotides probes, have successfully been used for sensing/detection of small molecules and macromolecules. Thus, an aptamer specific to METH may favor development of a suitable nanobiosensor for fast and sensitive detection of METH. To select ssDNA aptamer with high binding affinity and specificity to METH, in the current investigation, we screened a synthetic ssDNA library utilizing the systematic evolution of ligands by exponential enrichment (SELEX) technology. Methamphetamine-modified epoxy-activated sepharose 6B was used to extract specific aptamer from a large and diverse random ssDNA initial oligonucleotide library. As a result, several aptamers were selected and further examined for binding affinity and specificity. One of the selected aptamers (aptaMETH) displayed high affinity to the target molecule METH, yielding K-d value at nM range (similar to 100 nM), that was able to efficiently discriminate METH from similar molecular structures (e.g., amphetamine). METH was detected by aptaMETH using an electrochemical impedance spectroscopic sensing method. Our findings show high affinity and specificity of the aptaMETH against methamphetamine, thus we propose it as a suitable probe for development of METH-sensing aptasensors.