Description:
<jats:title>Abstract</jats:title>
<jats:p>The thermophilic bacterium <jats:italic>Thermus thermophilus HB27</jats:italic> encodes chromosomal arsenate reductase (<jats:italic>TtArsC</jats:italic>), the enzyme responsible for resistance to the harmful effects of arsenic. We report on adsorption of <jats:italic>TtArsC</jats:italic> onto gold nanoparticles for naked-eye monitoring of biomolecular interaction between the enzyme and arsenic species. Synthesis of hybrid biological–metallic nanoparticles has been characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV–vis), dynamic light scattering (DLS) and phase modulated infrared reflection absorption (PM-IRRAS) spectroscopies. Molecular interactions have been monitored by UV–vis and Fourier transform-surface plasmon resonance (FT-SPR). Due to the nanoparticles’ aggregation on exposure to metal salts, pentavalent and trivalent arsenic solutions can be clearly distinguished by naked-eye assay, even at 85 <jats:italic>μ</jats:italic>M concentration. Moreover, the assay shows partial selectivity against other heavy metals.</jats:p>