DNA-NEMS sensor from diamond

• Applicants: Professor Dr. Oliver Ambacher; Professor Dr.-Ing. Nianjun Yang, Ph.D.
• Subject Area: Microsystems ; Analytical Chemistry ; Biophysics
• Term: from 2014 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 234121274

• Final Report Year: 2017

Final Report Abstract

Detection of biological molecules such as DNA is crucial for medical diagnosis. For this purpose, we have developed and optimized a novel electrochemical sensor based on diamond nanotips for the detection of DNA-molecules. The detection principle is based on the dissimilar kinetic behavior of electrically manipulated single (ss) and double stranded (ds) DNA molecules, which are detected by Fouriertransform lock-in sensing of redox currents from ferrocene labels bonded to the marker DNA molecules. For this purpose we have processed spatially non ordered and ordered nano-textured diamond electrodes and used for controlled DNA bonding. The non-ordered diamond tips had a density of 10^11 cm^-2 and a separation distance of about 10 nm. The ordered arrays consisted of tips with diameters between 200 and 700 nm and a separation distance of about 1 µm. The tips of the nano-textured diamond electrodes were functionalized by nitro phenyl linker molecules followed by cross-linking of redox (ferrocene) labeled marker DNA strands. The redox activity of ferrocene terminated DNA on the textured diamond electrode before and after hybridization was characterized. The flexibility of single and double stranded DNA were investigated in solutions of different salt concentrations (3 mM to 1000 mM) under different ac electric fields. DNA attachment on flat diamond surfaces was realized using electrochemically grafted nitrophenyl linker, of which thickness was affected by the concentration of diazonium salts as well as applied reduction potential. AFM tapping mode imaging and AFM scratching experiments confirmed such a statement. Cyclic voltammetry of ferrocene-terminated single stranded DNA immobilized on diamond exhibits a pair of redox waves, while double stranded DNA does not. Cyclic voltammograms, differential pulse voltammograms, and impedance spectra were recorded. The diamond based sensor sensitivity with an active area of 3 mm2 was determined to 2 pM cm^-2. DNA detection with nano-textured diamond electrodes was observed to more than 100 times more sensitive in comparison to Au and flat diamond as transducers. In additon, electrochemical impedance spectroscopy as well as cyclic voltammetry was applied to characterize the diamond tips with respect to redox molecule and neurotransmitter sensing. By optimizing the surface termination of the nano-electrodes with hydrogen, the electron transfer significantly increased and adsorption features due to hydrophilic properties have been detected. The nanotip array showed a high faradaic current to capacitive current ratio at slow scan rates and in high concentration of supporting electrolyte. Ultra-fast cyclic voltammetry with up to 100 V/s has been performed without a change of sigmoidal current characteristic. In addition, sensitive and reproducible detection of dopamine has been demonstrated on hydrogen-terminated diamond arrays at slow scan rates. The detection limit of dopamine in the presence of ascorbic acid was 1.0 nM, which is 50-100 times lower than that obtained on the macro-sized boron-doped diamond electrodes. In summary, these results show that the arrays in combination with optimized surface terminations offer new electrochemical sensing possibilities which are currently under investigation.

Publications

• Diamond Ultramicro- and Nano- Electrode Arrays in Novel Aspects of Diamond (book chapter). In Novel Aspects of Diamond (ed.) N. Yang, Springer, 2014, pp 275
  N. Yang, J. Hees, C. E. Nebel
  
• Nano-diamond based spheres for radio frequency electromechanical resonators. Journal of Micromechanics and Microengineering. 24 (2014), 7
  V. Lebedev, D. Iankov, N. Heidrich, V. Zürbig, C. Wild, V. Cimalla, O. Ambacher
  
• Appropriate salt concentration of nanodiamond colloids for electrostatic self-assembly seeding of monosized individual diamond nanoparticles on silicon dioxide surfaces. Langmuir 31 (2015), 19, 5319
  T. Yoshikawa, V. Zürbig, F. Gao, R. Hoffmann, C. Nebel, O. Ambacher, V. Lebedev
  
• Detection of different target-DNA concentrations with highlysensitive AlGaN/GaN high electron mobility transistors. Sensors and Actuators B: Chemical 210 (2015), 633
  N. Espinosa, S. U. Schwarz, V. Cimalla, O. Ambacher
  
• Impedance characterization of DNA-functionalization layers on AlGaN/GaN high electron mobility transistors. Procedia Engineering 120 (2015), 912
  N. Espinosa, S. U. Schwarz, A. Podolska, O. Ambacher
  
• Diamond Electrochemistry at the Nanoscale: A Review. Carbon 99 (2016) 90
  N. Yang, J. S. Foord, X. Jiang
  
• Diamond Nanostructures and Nanoparticles: Electrochemical Properties and Applications (book chapter). In Carbon Nanoparticles and Nanostructures. N. Yang, X. Jiang, D.-W. Pang, Springer, 2016, pp 299
  N. Yang and X. Jiang
  
• Electrochemistry of Carbon Dioxide on Carbon Electrodes. ACS Applied Materials and Interfaces, 8 (2016) 8357
  N. Yang, S. R. Waldvogel, X. Jiang
  
• Nanocarbon Electrochemistry and Electroanalysis: Current Status and Future Perspectives. Electroanalysis 28 (2016) 27
  N. Yang, G. M. Swain, X. Jiang
  
• Battery-Like Supercapacitors from Diamond Networks and Water-Soluble Redox Electrolytes. Journal of Material Chemistry A 5 (2017) 1778
  S. Yu, N. Yang, H. Zhuang, S. Mandal, O. A. Williams, Yang, N. Huang, X. Jiang
  
• Nanocarbons for DNA Sequencing, A Review. Carbon, 115 (2017) 293
  N. Yang, X. Jiang