Hybrid systems for biosensing on chip V. Arima

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Hybrid systems for biosensing on chip

  • V. Arima

  • National Nanotechnology Laboratory of INFM-CNR

  • HI-Tech. – District – ISUFI

  • University of Lecce

  • IIT- Italian Institute of Technology

  • Via Arnesano 73100 LECCE – ITALY

  • Valentina.arima@unile.it


Biosensing in nanotechnology

  • Fast and reliable detection of substances important to human welfare is much-needed, both in medicine and in the food industry. To this end, biosensors play an important role. The sensors will typically represent a combination of biochemistry, electronics or optics and surface chemistry

Electrochemical biosensors

DNA chips


  • Biosensing in nanotechnology

  • The electrical approach

  • Optical detection (Dr. P.P.Pompa)

Geometry of devices

Surface chemistry

Azurin monolayers on silicon oxide

Azurins on gold


  • Typical open-circuit resistance greater than 1 TΩ (100fA at 6V)

  • High throughput (90%)

  • Transport experiments at the surface of a solid

Interdigited electrods: towards an azurin-based biosensor

Electrical detection in DNA chips

PCR chips


  • Giuseppe Maruccio

  • Antonio Della Torre

  • Alessandro Bramanti

  • Elisabetta Primiceri

  • Eliana D’Amone

  • Diego Mangiullo

  • Stefania Sabella

  • Vanessa Frascerra

  • Adriana Biasco

  • Paolo Visconti

  • Pasquale Marzo

  • Roman Krahne

  • Ross Rinaldi

  • Franco Calabi

  • Roberto Cingolani

Electron beam lithography (EBL)

Fabrication of interdigited and planar electrods

  • Cleaning: ACE/ISO/N2 of SiO2

  • RIE Etching of SiO2: 12.6 CF4 / 20 O2 (sccm); power 200W, Pressure 40mtorr, time 6’

  • Gate deposition : Ag 60nm

  • Cleaning: ACE/ISO/N2

  • Photolithography: spin resist AZ5214E: 300 rpm for 3’’ or 4000 rpm for 40’’; soft bake at 1’ at 120°C exposure; Mask aligner 12’’ (soft-contact); development solution AZ726 MIF ~1’15’’

  • Deposition : Cr/Au 6nm/60nm; lift-off ACE (Ultrasound in acetone)

  • Cleaning: ACE/ISO/N2

Fabrication of mesa structures

  • Cleaning: ACE/ISO/N2 of the quantum well

  • Photolithography: spin resist AZ5214E; Mask aligner (soft-contact); development solution H2O/ H2O2/H2PO4 with a ratio of 50:1:1 for 120 s at 24°C

  • Cleaning: ACE

  • selective wet etching (using citric acid and H2O2 at a ratio of 5:1) to remove a few tens of nms of the GaAs layer from the sloped edges of the mesa

  • Home-made oven consisting of a cylindrical quartz chamber embedded in a solenoid and heated by the Joule effect. A N2 flow and the temperature of the water source were optimized at the values of 3.3 l/min-1 and 80 °C, respectively

  • Photolithography: spin resist AZ5214E; soft bake at 1’ at 120°C exposure; Mask aligner 12’’ (soft-contact); development solution AZ726 MIF ~1’15

  • Deposition : Cr/Au 5nm/10nm; lift-off ACE

  • Cleaning: ACE/ISO/N2

Azurin-functionalized mesa devices

  • Deposition: cast deposition of a 20 ml drop of protein solution (1.0 mg/ml in 50 mM NH4Ac buffer, pH 4.6).

  • Intramolecular electron transfer from the disulfide radical ion RSSR- to the Cu(II) center was reported by Farver et al who also identified the amino acids that provide the pathway with the strongest coupling.

  • Only few proteins in parallel participate in the current transport (intramolecular ET )

  • On/off resonance conditions in tunneling through the redox levels (localized states on RSSR and Cu(II))

  • Almost symmetric position of the dI/dV peaks

  • Small differences in the resonant conditions.

  • A quantitative comparison between the ET rate obtained here and those quoted in the literature, provided primarily by spectroscopic and electrochemical techniques, is not possible due to the different environmental conditions.

  • In Farver’s experiment, the created disulfide radical ion decays spontaneously by an intramolecular ET to the Cu(II) center, while an intense electric field is present in the tunneling junction, which can strongly enhance this process.

  • Redox centers strongly coupled to the vibrational nuclear environment. Broad peaks attributed to fluctuations in the nuclear configuration (due to an interaction with the environment) which shift the energy levels of the redox centers.

AFM on Azurins

Protein FET

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