Natural ionophore functionalized nanobiosensor capable of staining Cr3+ in live brine shrimp Artemia

Abstract

We report the fabrication of gold nanoparticles using a sulfur containing microbial ionophore aeruginic acid (H2L), functioning as a reducing as well as stabilizing agent, to develop a nanobiosensor HL-AuNPs which showed highly selective colorimetric detection of Cr3+ in aqueous (100% water) HEPES buffer at physiological pH. On exposing HL-AuNPs to the aqueous solution of Cr3+, a red shift in the surface plasmon resonance (SPR) band of the probe is observed along with bare eye observable color change of the solution. Mechanistic studies revealed attachement of carboxylate moiety to the gold nanosurface. On addition of Cr3+ to the solution of HL-AuNPs, aggregation occurs as a result of coordination of the phenolate O and imine N with the octahedral Cr3+ center. The nanosensor with lower detection limit (LOD) of 0.5 μM can also be utilized for colorimetric detection and removal of Cr3+ in environmental samples. Being non-toxic and permeable in nature, HL-AuNPs can function as a colorimetric staining reagent for Cr3+ in living whole brine shrimp Artemia. Use of functionalized AuNPs as imaging reagent for Cr3+ in living organim is unprecedented.