Disulfide-Terminated Aryldiazonium Salt Compound and Method for Preparing the Same

Novel Linker Compound Combining Disulfide and Aryldiazonium for Biomolecule Immobilization in Biosensors

This technology features a DSAD salt compound containing both a disulfide terminus, activated by electrochemical oxidation, and an aryldiazonium moiety that grafts onto ITO electrodes and reduced graphene oxide (RGO) surfaces. The synthesis involves three steps: amide bonding of lipoic acid with N-Boc-1,4-phenylenediamine, Boc deprotection, and diazotization to yield 5-(1,2-dithiolan-3-yl)pentanamide-4-benzene diazonium chloride.

While alkanethiol self-assembled monolayers on gold, silanization on ITO, and electrochemical diazonium grafting have been used for sensor surface modification, no disulfide-terminated aryldiazonium molecules suitable as linkers have been reported. Furthermore, despite its excellent electrical properties, RGO has faced limitations due to the lack of established techniques for efficient functionalization with diazonium for biosensor applications.

This technology uses a single compound to perform both electrode grafting and covalent bonding of antibody thiol groups, enabling spatially selective immobilization—activating only specific parts of microelectrodes—and covalent functionalization of graphene surfaces. This linker can be applied to sandwich ELISA chips, graphene-based immunosensors, and high-speed diagnostic biochips, providing diagnostic kit manufacturers with a foundational material for high-sensitivity antibody immobilization platforms without requiring separate surface treatments.

‍

‍

Key Features:

• A disulfide-terminated aryldiazonium salt compound of Formula 1, where R is hydrogen or a C1-C4 alkyl group, Ar is a C6-C30 aryl group, and X is a halogen
• Synthesizing a tert-butyl carbamate intermediate by reacting lipoic acid with N-Boc-1,4-phenylenediamine in the presence of TEA, HOBt, and EDCl
• Deprotecting the intermediate in a mixture of DCM and TFA, followed by diazotization with hydrochloric acid and sodium nitrite to obtain pentanamide-4-benzene diazonium chloride
• Use as a linker for spatially selective immobilization of biomolecules in sandwich immunoassays by binding to microelectrode arrays or electrochemically reduced graphene oxide surfaces

‍

This invention was developed with support from the Ministry of Education, Science and Technology for the development of electrochemical biosensors using bacteriophages.

‍