Surface Grafting of Graphene Flakes with Fluorescent Dyes: A Tailored Functionalization Approach

TL;DR

This paper introduces a highly selective covalent functionalization method for graphene flakes using 1,3-dipolar cycloaddition with a custom ylide, enabling attachment of fluorescent dyes for biological and nanodevice applications.

Contribution

It extends 1,3-dipolar cycloaddition to low-defect graphene and employs a novel protected ylide for controlled functionalization, minimizing structural damage.

Findings

Successful covalent attachment of fluorescent dyes confirmed by spectroscopy.

Method enables selective functionalization with minimal graphene damage.

Potential applications in biological imaging and nanodevice development.

Abstract

The controlled functionalization of graphene is critical for tuning and enhancing its properties, thereby expanding its potential applications. Covalent functionalization offers a deeper tuning of the geometric and electronic structure of graphene compared to non-covalent methods; however, the existing techniques involve side reactions and spatially uncontrolled functionalization, pushing research toward more selective and controlled methods. A promising approach is 1,3-dipolar cycloaddition, successfully utilized with carbon nanotubes. In the present work, this method has been extended to graphene flakes with low defect concentration. A key innovation is the use of a custom-synthesized ylide with a protected amine group (Boc), facilitating subsequent attachment of functional molecules. Indeed, after Boc cleavage, fluorescent dyes (Atto 425, 465, and 633) were covalently linked via NHS ester derivatization. This approach represents a highly selective method of minimizing structural damage. Successful functionalization was demonstrated by Raman spectroscopy, photoluminescence spectroscopy, and confocal microscopy, confirming the effectiveness of the method. This novel approach offers a versatile platform, enabling its use in biological imaging, sensing, and advanced nanodevices. The method paves the way for the development of sensors and devices capable of anchoring a wide range of molecules, including quantum dots and nanoparticles. Therefore, it represents a significant advancement in graphene-based technologies.