title: Scanning electrochemical microscopy of DNA hybridization on DNA microarrays enhanced by HRP-modified SiO2 nanoparticles.
abstract: Imaging of localized hybridization of nucleic acids immobilized on a glass DNA microarray was performed by means of generation collection (GC) mode scanning electrochemical microscopy (SECM). Amine-tethered oligodeoxynucleotide probes, spotted on the glass surface, were hybridized with an unmodified target sequence and a biotinylated indicator probe via sandwich hybridization. Spots where sequence-specific hybridization had occurred were modified by streptavidin-horseradish-peroxidase-(HRP)-wrapped SiO2 nanoparticles through the biotin-streptavidin interaction. In the presence of H2O2, hydroquinone (H2Q) was oxidized to benzoquinone (BQ) at the modified spot surface through the HRP catalytic reaction, and the generated BQ corresponding to the amount of target DNA was reduced in solution by an SECM tip. With this DNA microarray, a number of genes could be detected simultaneously and selectively enough to discriminate between complementary sequences and those containing base mismatches. The DNA targets at prepared spots could be imaged in SECM GC mode over a wide concentration range (10(-7)-10(-12) M). This technique may find applications in genomic sequencing.
authors.affiliation: Department of Chemistry, East China Normal University, Shanghai 200241, P. R. China.
authors.forename: Huajun
authors.initials: H
authors.lastname: Fan
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Wang
authors.forename: Fang
authors.initials: F
authors.lastname: Jiao
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: Qingjiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Pingang
authors.initials: P
authors.lastname: He
authors.forename: Yuzhi
authors.initials: Y
authors.lastname: Fang
mesh_terms: D006735:Horseradish Peroxidase / Q000737:chemistry*; D064347:Microscopy, Electrochemical, Scanning / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*; D009693:Nucleic Acid Hybridization / Q000379:methods; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D012822:Silicon Dioxide; D006735:Horseradish Peroxidase