Assembly Of Functional Molecules Modified Gold Nanoparticles Systems And Their Application

Gold nanoparticles (AuNPs) have received much attention in fields of environmental management, food safety, food safety, catalyst development and so on, owing to their unique properties in optics, electricity, magnetics, catalysis, favorable stabilization and biocompatibility. In this work, functional molecules modified AuNPs have been fabricated, and recognition study proceeded toward melamine, mercury ion, and lead ions in foods and environment based on the unique surface Plasmon resonance properties as follows.Firstly, functional molecule with quaternary ammonium salt moiety and thymine moiety was designed and synthesized, which was then used for modification on surface of AuNPs (N-T/AuNPs) due to the electrostatic effect. And this system could be used for the colorimetric recognition of melamine based on the thymine-Hg2+-thymine chemistry. The presence of melamine in the testing system could result in the aggregation of nanoparticle along with obvious red-to-blue color changes. This N-T/AuNPs system exhibited excellent properties in selectivity, sensitivity, and good linear range of 0.2～0.45 μM (with limit of detection, LOD, at 3.5 nM) for melamine recognition.Secondly, on the platform of N-T/AuNPs, the convenient, fast, and simple Hg2+ recognition was achieved by the thymine-Hg2+-thymine chemistry. The addition of Hg2+ induced aggregation of AuNPs, resulting in red-to-blue colorimetric changes. Among the testing heavy metal ions and transition metal ions, the N-T/AuNPs system showed special recognition capability to Hg2+ with LOD of 0.8 nM.Finally, the urea-AuNPs system was fabricated for the selective recognition of Pb2+ due to the coordination chemistry between urea and Pb2+. The presence of Pb2+ induced red-to-blue color changes on the basis of particles’ aggregation, leading to fast, the selective, and sensitive recognition of Pb2+ with linear testing range over 4-20 μM and LOD of 0.15 μM.