Self-assembled monolayer-assisted silicon nanowire biosensor for detection of protein-DNA interactions in nuclear extracts from breast cancer cell.
The large number of estrogen receptor (ER) binding sites of various sequence patterns requires a sensitive detection to differentiate between subtle differences in ER-DNA binding affinities. A self-assembled monolayer (SAM)-assisted silicon nanowire (SiNW) biosensor for specific and highly sensitive detection of protein-DNA interactions, remarkably in nuclear extracts prepared from breast cancer cells, is presented. As a typical model, estrogen receptor element (ERE, dsDNA) and estrogen receptor alpha (ERα, protein) binding was adopted in the work. The SiNW surface was coated with a vinyl-terminated SAM, and the termination of the surface was changed to carboxylic acid via oxidation. DNA modified with amine group was subsequently immobilized on the SiNW surface. Protein-DNA binding was finally investigated by the functionalized SiNW biosensor. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were employed to characterize the stepwise functionalization of the SAM and DNA on bare silicon surface, and to visualize protein-DNA binding on the SiNW surface, respectively. We observed that ERα had high sequence specificity to the SiNW biosensor which was functionalized with three different EREs including wild-type, mutant and scrambled DNA sequences. We also demonstrate that the specific DNA-functionalized SiNW biosensor was capable of detecting ERα as low as 10 fM. Impressively, the developed SiNW biosensor was able to detect ERα-DNA interactions in nuclear extracts from breast cancer cells. The SAM-assisted SiNW biosensor, as a label-free and highly sensitive tool, shows a potential in studying protein-DNA interactions.
Institute of Microelectronics, A*STAR (Agency for Science, Technology and Research), Singapore Science Park II, Singapore, Singapore. zhanggj@ime.a-star.edu.sg
Guo-Jun
GJ
Zhang
Min Joon
MJ
Huang
Jun'An Jason
JJ
Ang
Edison T
ET
Liu
Kartiki Vasant
KV
Desai
D015374:Biosensing Techniques / Q000379:methods*; D001943:Breast Neoplasms / Q000378:metabolism*; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D005260:Female; D006801:Humans; D018625:Microscopy, Atomic Force; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D056951:Photoelectron Spectroscopy; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D012680:Sensitivity and Specificity; D012825:Silicon / Q000737:chemistry*
D011506:Proteins; D004247:DNA; D012825:Silicon