title: Direct label free ultrasensitive impedimetric DNA biosensor using dendrimer functionalized GaN nanowires.
abstract: We demonstrate a very simple and generic protocol for ultrasensitive in-situ label-free detection of DNA hybridization using third generation poly(amidoamine)dendrimer (G3-PAMAM) functionalized GaN nanowires (NWs). PAMAM modified GaN NWs provides large density of docking site to immobilize significant number of probe (p-) DNA covalently. These p-DNA/PAMAM/GaN NWs sensor probes are employed to achieve an ultra-high detection limit down to attomolar level concentration of complementary target (t-) DNA. Comparative in-situ studies on single/triple base-pair mismatched, γ-irradiated and complementary t-DNA in the hybridization process reveal selectivity and specificity of the p-DNA/PAMAM/GAN NWs sensor probe over a wide range, 10(-8) to 10(-19)M, of analyte concentration. During the hybridization process, there is a substantial change in t-DNA concentration dependent interfacial polarization resistance during electrochemical impedance measurement, which forms the basis of the present DNA biosensor. This novel methodology for specific DNA sequence detection, as compared with the existing methods, is found to be very robust, highly sensitive, and reproducible.
authors: Surface and Nanoscience Division, Indira Gandhi Center for Atomic Research, Kalpakkam, India. prasanasahoo@gmail.com
authors: Prasana
authors: P
authors: Sahoo
authors: Sumathi
authors: S
authors: Suresh
authors: Sandip
authors: S
authors: Dhara
authors: Garima
authors: G
authors: Saini
authors: S
authors: S
authors: Rangarajan
authors: A K
authors: AK
authors: Tyagi
mesh_terms: D000818:Animals; D001483:Base Sequence; D015374:Biosensing Techniques / Q000379:methods*; D015342:DNA Probes / Q000737:chemistry; D004279:DNA, Viral / Q000032:analysis* / Q000302:isolation & purification; D050091:Dendrimers / Q000737:chemistry*; D017097:Electric Impedance; D005708:Gallium / Q000737:chemistry*; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification; D057230:Limit of Detection; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D009693:Nucleic Acid Hybridization / Q000379:methods; D009976:Orthomyxoviridae Infections / Q000175:diagnosis / Q000662:veterinary / Q000821:virology; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis / Q000821:virology
chemical_list: D015342:DNA Probes; D004279:DNA, Viral; D050091:Dendrimers; C104700:PAMAM Starburst; C473348:gallium nitride; D005708:Gallium