A surface-enhanced Raman scattering (SERS) biosensor fabricated using the electrodeposition method for ultrasensitive detection of amino acid histidine

Abstract

The amino acid histidine is an important bioactive molecule for growth and tissue repair and has an influential role as a neurotransmitter in the human musculoskeletal and central nervous systems. Therefore, excessive deficiency of this amino acid and the proteins induced by it causes many diseases. For this reason, the specific and sensitive detection of the amino acid histidine is very important. Surface-enhanced Raman scattering (SERS) is a sensitive method for detecting low concentrations of various substances, especially biomaterials. The silver nanoparticles (AgNPs)-coated substrates were employed in the present investigation to detect the amino acid histidine to control the diseases caused by it. First, a chemical method named Tollens was applied to fabricate AgNPs, and then, the Fluorine-doped tin oxide (FTO) substrates were coated with AgNPs by applying voltage and through the electrodeposition technique. Therefore, AgNPs were fabricated using the Tollens method, as well as the size distribution of nanoparticles was specified as being equal to 130–150 nm by employing dynamic light scattering. Moreover, UV–Vis spectroscopy was employed for the characterization of prepared substrates and AgNPs. The results show that the plasmonic peak tends toward longer wavelengths following the self-array of AgNPs. In addition, it was proved by the field-emission scanning electron microscope (FE-SEM) images that AgNPs on the surface of FTO substrates were distributed non-uniformly. The limit of detection (LOD) was equal to 10−9 for SERS-active substrates for the purpose of detecting this amino acid. Moreover, for ten repeated calculations, the mean relative standard deviation (RSD) was achieved to be 3.86%. Furthermore, the values for the enhancement factor were obtained to be 1.344 × 105 and 1.389 × 105 via experimental and simulation methods, respectively. Thus, the results obtained from Raman indicate that by applying the developed methods, SERS-active substrates coated with AgNPs for the detection of amino acid histidine show advantageous results for SERS-based investigations and can cause the development of nanosensors.