Colorimetric detection of manganese(II) ions using gold/dopa nanoparticles.
We report here a one-pot, greener, eco-friendly strategy for the synthesis of gold nanoparticles using L-dopa. The as-prepared dopa-functionalized gold nanoparticles (AuNPs/dopa) can detect low concentrations of manganese(II) metal ions in aqueous solution. The binding forces between dopa and Mn(2+) ions cause dopa-functionalized gold nanoparticles to come closer together, decreasing the interparticle distance and aggregating it with a change in color of colloidal solution from red to purplish-blue. Dynamic light scattering (DLS) analysis showed a decreased surface charge on the surface of gold nanoparticles when exposed to Mn(2+) ions, which caused cross-linking aggregation. Transmission electron microscopic (TEM) images also revealed the aggregation of gold nanoparticles with the addition of Mn(2+) ions. The extinction ratio of absorbance at 700-550nm (A700/A550) was linear against the concentration of [Mn(2+)] ions. Thus, the optical absorption spectra of gold colloidal solution before and after the addition of Mn(2+) ions reveal the concentration of Mn(2+) ions in solution.
Department of Biochemistry, School of Biotechnology, Yeungnam University, Gyeongsan 712 749, South Korea.
Kannan Badri
KB
Narayanan
Department of Biochemistry, School of Biotechnology, Yeungnam University, Gyeongsan 712 749, South Korea. Electronic address: hyunho@ynu.ac.kr.
Hyun Ho
HH
Park
D002413:Cations, Divalent / Q000032:analysis; D003124:Colorimetry / Q000379:methods; D006046:Gold / Q000737:chemistry*; D007980:Levodopa / Q000737:chemistry*; D008345:Manganese / Q000032:analysis*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size
D002413:Cations, Divalent; D008345:Manganese; D007980:Levodopa; D006046:Gold
Dopa; Eco-friendly; Gold nanoparticles; Manganese(II); Metal ions; Sensor