Localized Surface Plasmon Resonance (LSPR)-Based Nanobiosensor for Methamphetamin Measurement

Aptamers are DNA or RNA single-stranded molecules that bind specifically to target molecules with high affinity. Function of nucleic acid aptamers is based on organized tertiary structure of them that is related to primary sequence, length of nucleic acid molecule, and environmental conditions. Herein, a localized surface plasmon resonance (LSPR) nanobioprobe has been developed based on specific aptamer-conjugated gold nanoparticles for rapid detection of methamphetamine. Detection of methamphetamine was studied via monitoring the gold nanoparticles (GNPs) LSPR band alterations in the presence of different concentrations. The covalent conjugation has been confirmed with FT-IR spectroscopy, and size alterations of gold nanoparticles before and after the conjugation state were monitored using dynamic light scattering (DLS) technique. The results show high affinity of aptamer to methamphetamine. Moreover, the results show conjugated aptamer with GNP in different concentrations of methamphetamine that contribute to color changes that is visible with unaided eye. Also, 14 nm LSPR shift was seen after conjugation of aptamer with GNP. Nanoparticle diameter after conjugation with aptamer was increased from 30 to 91 nm and decreased after incubation with methamphetamine (due to folding) from 91 to 84 nm. Detection limit of this designed nanoprobe is 500 nM. Plasmonic nanoparticle-based nanobioprobe is a new field for development of sensitive detection systems.