Covalent Attachment of Aggregation-Induced Emission Molecules to the Surface of Ultrasmall Gold Nanoparticles to Enhance Cell Penetration.

Matthias Hayduk,Kai Klein,Marco Schmiedtchen,Jens Voskuhl,Sebastian Kollenda,Matthias Epple

doi:10.3390/molecules27061788

Abstract

Three different alkyne-terminated aggregation-induced emission molecules based on a para-substituted di-thioether were attached to the surface of ultrasmall gold nanoparticles (2 nm) by copper-catalyzed azide–alkyne cycloaddition (click chemistry). They showed a strong fluorescence and were well water-dispersible, in contrast to the dissolved AIE molecules. The AIE-loaded nanoparticles were not cytotoxic and easily penetrated the membrane of HeLa cells, paving the way for an intracellular application of AIE molecules, e.g., for imaging.

Highlights

Emission Molecules to the Surface of Ultrasmall metallic nanoparticles are versatile tools for imaging, catalysis, and drug delivery [1–12]
We have reported previously how ultrasmall gold nanoparticles can be covalently surface-functionalized with dyes or protein binders via copper-catalyzed azide–alkyne cycloaddition onto azide-terminated gold nanoparticles [19,22,23,27]
AIEligands ligandswith withthe thesame same fluorophore, with different polarity hyphilicity, were investigated. They were based on a known fluorophore drophilicity, were investigated (Figure 1). They were based on a known fluorophore and functionalized with with an alkyne group for covalent attachment to thetonanoparticles

Summary

Introduction

Emission Molecules to the Surface of Ultrasmall metallic nanoparticles are versatile tools for imaging, catalysis, and drug delivery [1–12]. They are at the borderline between metallic nanoparticles and atom-sharp metal clusters [4,13–16]. Their synthesis is usually performed “bottom-up” by the reduction of metal salts with NaBH4 , following the Brust–Schiffrin synthesis [24,25]. They have been prepared “top-down” by pulsed laser ablation in the form of unprotected gold clusters [26]. We have reported previously how ultrasmall gold nanoparticles can be covalently surface-functionalized with dyes or protein binders via copper-catalyzed azide–alkyne cycloaddition (click chemistry) onto azide-terminated gold nanoparticles [19,22,23,27]

Methods

Results

Conclusion