A monolithic silicon based integrated signal generation and detection system for monitoring DNA hybridisation

• Published in: Biosensors & bioelectronics Vol. 21; no. 4; pp. 565 - 573
• Main Authors: Bertolino, Chiara, MacSweeney, Marion, Tobin, Jane, O’Neill, Brendan, Sheehan, Michelle M., Coluccia, Salvatore, Berney, Helen
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15-10-2005; Elsevier Science
• Subjects: Biological and medical sciences; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Biosensors; Biotechnology; DNA - analysis; DNA - chemistry; DNA biosensor; Electrochemiluminescence; Electrochemistry - instrumentation; Electrochemistry - methods; Equipment Design; Equipment Failure Analysis; Fundamental and applied biological sciences. Psychology; In Situ Hybridization - instrumentation; In Situ Hybridization - methods; Luminescent Measurements - instrumentation; Luminescent Measurements - methods; Methods. Procedures. Technologies; PIN photodiode; Point of care diagnostic; Reproducibility of Results; Semiconductors; Sensitivity and Specificity; Silicon - chemistry; Systems Integration; Various methods and equipments; Electrochemiluminescence; DNA biosensor; PIN photodiode; Point of care diagnostic; Molecular hybridization; Biosensor; Point of care testing; DNA; Silicon; Diagnosis; Photodiode; Detection
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2004.12.007

The aim of this work was to develop an integrated solution to DNA hybridisation monitoring for diagnostics on a monolithic silicon platform.
A fabrication process was developed incorporating a gold initiation electrode patterned directly onto a PIN photodiode detector. Patterned interdigitated type electrodes exhibited the smallest reduction in photodiode sensitivity, therefore these were chosen as the ECL initiator design.
A novel DNA hybridisation assay was developed based on the displacement of a partially mismatched complementary strand by a perfectly matched labelled complementary strand. Prehybridised thiolated oligonucleotide and unlabelled 25% mismatched oligonucleotide were assembled on the gold initiation electrode. On addition of the labelled perfectly complementary oligonucleotide, the mismatched strands were displaced and a signal was generated.
The sensitivity of the photodiode to light emitted at 620
nm, the ruthenium emission wavelength, was determined and subsequently, the diode current response to light generated by flow addition of ruthenium solution was found to be measurable to a concentration of 10
fM.
Prehybridised duplex DNA, consisting of thiolated oligonucleotide and ruthenium labelled complementary oligonucleotide, was assembled on the gold initiation electrode. The difference between the current measured during flow of buffer and the ECL coreactant TPA was three orders of magnitude, indicating that DNA assembled on the surface comprised sufficient ruthenium to generate a measurable signal. Finally, the displacement of unlabelled partial mismatch oligonucleotide from the sensor surface was monitored on addition of the ruthenium labelled perfectly complementary oligonucleotide in TPA flow and the measured photodiode current response was up to 50 times greater.