Terpyridine functionalized gold nanoparticles: Assembling induced by metal ions and subsequent disassembly by pyrophosphate

Key Words:SELECTIVE SENSING PROBE; COLORIMETRIC DETECTION; CALCIUM-IONS; AGGREGATION; RECOGNITION; ASSAY

Abstract:The assembling and disassembling of gold nanoparticles (AuNPs) are usually accompanied by color changes due to the localized plasmon resonance, and thus can be applied to develop colorimetric detection. In this work, AuNPs were modified by a novel ligand of terpyridine derivative to fabricate terpyridine-functionalized AuNPs (Au@TPY). The interaction between the Au@TPY and metal ions induced the nanoparticles to assemble into aggregates, showing a distinct color change from red to blue. The divalent ions, Mn2+, Co2+ and Zn2+ exhibited the strongest ability to induce the assembling of the Au@TPY, along with SPR redshifts of more than 88 nm; while Ni2+, Cd2+, Fe2+, Sr2+ and Sn2+ only showed a SPR redshift of around 70 nm. Subsequently, after adding pyrophosphate (PPi), the samples of Mn2+, Co2+, Mg2+, Sr2+, Sn2+, and Hg2+ induced aggregates of the Au@TPY displayed rapid color recovery to red with SPR peaks back to 540-550 nm. Furthermore, the Mn2+-induced Au@TPY aggregates were used to study the disassembling induced by various anions. It was found that PPi, at double Mn2+ amount, brought a rapid disassembling of the aggregated Au@TPY, and a more amount of oxalate and citrate also disassembled the aggregates. This verifies that the weaker coordinating systems of the Au@TPY and metal ions can be easily destroyed via a competing coordination of PPi with terpyridine moieties to metal ions. The terpyridine-modified plasmonic nanoparticles are meaningful to develop colorimetric recognition platforms in the detection of metal ions and anions.

Volume:719

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Translation or Not:no