Enhanced DNA hybridization on nanostructured silicon surfaces

^1,3Shalini Singh^*, ²Jyoti Zack, ¹Dinesh Kumar, ¹Sanjay K. Srivastava, ²Daman Saluja, ³Mukhtar A. Khan and ¹P. K. Singh

¹Electronic Materials Division, National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi-110012, India

²Dr. B.R Ambedkar Center for Biomedical Research, University of Delhi, Delhi-110007, India

³Faculty of Life Science, Aligarh Muslim University, Aligarh-202001, India

Deoxyribonucleic Acid (DNA) chip technology is of interest in the development of diagnostic devices and drug delivery applications. Silicon has been widely used for the fabrication of micro-electro-mechanical system (MEMS) and smart sensors which are now commercially available. The aim of this work is to develop a sensor for specific DNA sequences.  The high sensitivity of the biochip was achieved by increasing the specific surface area of the device.  DNA attachment and the subsequent hybridization on different silicon surfaces, which may have potential application as DNA chips, was carried out. Silicon surfaces with wide range of surface to volume ratio having topographies (nanoporous and nanowires) were prepared by chemical etching of silicon wafer. These samples were used for attachment of single-stranded probe DNA (20-21mer) after chemical modification. Both qualitative and quantitive characterization was carried out by using radiolabelled (P³²) DNA sequence for hybridization with attached DNA. Using Nanodrop technique we have been able to show the enhanced DNA surface density after hybridization on silicon surfaces designed in the present study (nanoporous and nanowires) as compared to the flat silicon surfaces. More than 70% of DNA binding was achieved on the porous silicon and silicon nanowires surfaces in comparison to less than 20% of DNA binding on flat silicon surface. Enhanced DNA binding clearly demonstrates the enhanced detection sensitivity and therefore such surfaces can be used to develop   nucleic acid based biosensors and diagnostic chips.

The detailed protocol related to the above study will be presented in the conference.