Highly chemiluminescent gold nanopopcorns functionalized by N-(aminobutyl)-N-(ethylisoluminol) with lipoic acid as a co-stabilizing reagent

Abstract

Herein we report a novel facile synthesis of Au nanopopcorns (AuNPCs) with high chemiluminescent yield by reducing (±)-α-lipoic acid (LA) and HAuCl₄ with N-(aminobutyl)-N-(ethylisoluminol) (ABEI) in ethyl alcohol solution at room temperature through a seed growth method. The morphologies of AuNPCs could be changed by adjusting the mole ratios of ABEI, LA and HAuCl₄. The characterization results demonstrated that ABEI and the reduction product of LA as stabilizers were coated on the surface of AuNPCs during the synthesis. The AuNPCs, functionalized with ABEI, could react with various oxidants (H₂O₂, KMnO₄, NaClO, Fe(CN)₆³⁻ and AgNO₃) to produce chemiluminescence (CL). The special morphology of AuNPCs maintains the large specific surface area, inherited from its shape and demonstrated excellent catalytic property when involved in CL reaction with H₂O₂. Thus the CL efficiency of AuNPCs was more than two orders of magnitude higher than that of ABEI functionalized gold nanoparticles in our previous work. The AuNPCs are capable of direct conjugation with protein and DNA while maintaining their luminescent properties, thus they could be potentially useful as a bio-probe for immunoassays and DNA assays.