Fluorescence quenching effects of nanocrystalline diamond surfaces

Undoped diamond has conductive properties when terminated by hydrogen and exposed to air or aqueous solution. Here, it is shown that nanocrystalline diamond, fabricated with hydrogen termination and deposited on quartz substrates using chemical vapor deposition, significantly quenched the fluorescence of adsorbed, dye-labeled fibrinogen protein in aqueous solutions at near neutral pH. Smaller levels of quenching were observed from oxygen terminated NCD surfaces. We suggest that these near-surface fluorescence quenching effects may arise from surface conductance effects in hydrogen terminated NCD. It is also shown that despite bulk quenching effects, single molecules of fibrinogen could be imaged on nanocrystalline diamond surfaces using epi-fluorescence techniques.