Localized Surface Plasmon Resonance (LSPR)-Based Nanobiosensor for Methamphetamin Measurement Farshideh Qadami 1 & Ahmad Molaeirad 1 & Mahdi Alijanianzadeh 1 & Azadeh Azizi 1 & Nasrin Kamali 1 Received: 13 November 2017 /Accepted: 28 February 2018 # Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract 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 devel- oped based on specific aptamer-conjugated gold nanoparticles for rapid detection of methamphetamine. Detection of metham- phetamine 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. Keywords Aptamer . Gold nanoparticle . Methamphetamine . Plasmonic nanobioprobe Introduction Methamphetamine with regular about 15–16 million con- sumers is the world’ s second most widely consumed drug after cannabis [1]. Illegal use of methamphetamine and other nerve stimulator drug is a major challenge for public health officials and law enforcement agencies. The unique features of biosen- sors such as high sensitivity, accuracy, ease of use, and cost-effectiveness has led to this kind of sensors become a viable option for the production of diagnostic tools [2, 3]. The use of aptamer-based sensors because of the sensitivity and ease of production as an alternative to previous methods has attracted the attention of many researchers. Aptamers with the formation of secondary structure are able to connect and iden- tify specific targets [4]. Research progress contributes to the development of aptamers that can fold around small molecules such as methamphetamine [5, 6]. Sensor design with high per- formance depends on the development of new materials that both improve the diagnostic process and transmit signals. Gold nanoparticles have the unique chemical and physical properties such as high stability, unique optical properties, high surface to volume ratio, and excellent biocompatibility structure for the development of chemical and biological sensors [7–9]. The basis action of organized plasmonic sensors is plasmonic hy- bridization between the organized nanoparticles and expansion of their resonance related to changes of environmental dielectric coefficient around them [10–12]. So, with severe answered dielectric of these nanostructures that led to the widespread displacement in the resonant wavelength of them, even without a spectroscopic method and solely on the color change solution containing nanosensors, the desired detection could be achieved [13, 14]. Localized surface plasmon resonance (LSPR)-based nano- biosensors among the variety of existent biosensors are devel- oped as powerful tools with highly sensitive, label-free, and flexible sensing techniques for the detection of bio-molecular and chemical compounds. Traditional techniques such as * Ahmad Molaeirad molaeirad@gmail.com 1 Department of Bioscience and Biotechnology, Malek-Ashtar University of Technology, Tehran, Iran Plasmonics https://doi.org/10.1007/s11468-018-0725-3