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

## TL;DR

Researchers developed a new method to attach fluorescent dyes to graphene flakes, improving their potential for use in imaging and sensing.

## Contribution

A novel functionalization approach using a custom-synthesized ylide and controlled covalent bonding to graphene is introduced.

## Key findings

- Fluorescent dyes (Atto 425, 465, and 633) were successfully covalently attached to graphene flakes.
- The method minimizes structural damage and was confirmed using Raman and photoluminescence spectroscopy.
- The functionalization enables potential applications in biological imaging and advanced nanodevices.

## 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.