Interfacial Electrical Properties of DNA-Modified Diamond Thin Films:  Intrinsic Response and Hybridization-Induced Field Effects

Abstract

We have investigated the frequency-dependent interfacial electrical properties of nanocrystalline diamond films that were covalently linked to DNA oligonucleotides and how these properties are changed upon exposure to complementary and noncomplementary DNA oligonucleotides. Frequency-dependent electrical measurements at the open-circuit potential show significant changes in impedance at frequencies of >10(4) Hz when DNA-modified diamond films are exposed to complementary DNA, with only minimal changes when exposed to noncomplementary DNA molecules. Measurements as a function of potential show that at 10(5) Hz, the impedance is dominated by the space-charge region of the diamond film. DNA molecules hybridizing at the interface induce a field effect in the diamond space-charge layer, altering the impedance of the diamond film. By identifying a range of impedances where the impedance is dominated by the diamond space-charge layer, we show that it possible to directly observe DNA hybridization, in real time and without additional labels, via simple measurement of the interfacial impedance.

Synthetic diamond films as a platform material for label‐free protein sensors

“…The field-effect in NCD substrates, caused by negatively charged DNA at the surface, has been reported in our previous work on real-time impedimetric DNA detection [10] as well as in other publications [9,28] and will not be discussed here. A negligible field-effect in the NCD substrate was observed during CRP treatment, reflected by the lack of impedance variations in the semi-circle.…”

“…The fits were performed over the total frequency range from 100 Hz to 1 MHz. For most of the data, excellent fits (χ² ~ 10 -4 ) could be obtained by the commonly used model [9] illustrated in Fig. 4.…”

“…In 2004, Carlisle showed how chemical immobilisation of electro-active enzymes on conducting nanocrystalline diamond (NCD) thin films forms the basis for diamond-based electrochemical biosensors and bio-interfaces [8]. A very appealing property of DNA coatings covalently bound to diamond is their stability in aqueous electrolytes compared to other wellknown semiconductors used in the field of bio-electronics, such as Si [9].…”

Diamond nano-wires, a new approach towards next generation electrochemical gene sensor platforms

“…The same problem has been reported for nano-diamond films functionalized with amine groups as linker molecules, followed by cross-linking and DNA bonding which also resulted in a significantly quenched redox signal of Fe(CN) 6 3-/4-. [42] Typical DPV results as a function of complementary DNA concentration in SSPE buffer during hybridization are shown in Fig. 5b.…”

Electrochemical Sensors

“…190 The thiol functionalized probe was linked to the diamond surface after the surface was photochemically treated with 10-aminodec-1-one. The impedance change induced by DNA hybridization was monitored without the need for any label.…”