Organophosphonate biofunctionalization of diamond electrodes

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Electrochemistry

Background:

• Diamond surface modification is key for bioapplications.
• Covalently bound organic linkers are needed to broaden diamond's utility.
• Surface hydrophathicity and linker thickness impact immobilized protein function and electron transfer.

Purpose of the Study:

• To report the grafting of 6-phosphonohexanoic acid on hydroxyl-terminated diamond surfaces.
• To utilize these as linkers for tethering electroactive proteins.
• To assess the suitability of this functionalized diamond for bioelectronic interfaces.

Main Methods:

• Grafting of 6-phosphonohexanoic acid onto OH-terminated diamond.
• Surface characterization using X-ray photoelectron spectroscopy (XPS).
• Electrochemical characterization of immobilized aminomethylferrocene and cytochrome c.

Main Results:

• Confirmation of a stable 6-phosphonohexanoic acid layer on the diamond surface via XPS.
• Demonstration of efficient charge transfer between redox proteins and the diamond substrate.
• Successful covalent tethering of electroactive proteins using the phosphonohexanoic acid linker.

Conclusions:

• OH-terminated diamond functionalized with 6-phosphonohexanoic acid is a viable platform for interfacing redox-proteins.
• This approach supports protein immobilization with maintained functionality for bioelectronic applications.
• The developed method advances the development of biosensors and other bioelectronic devices.