title: Microfluidic biosensor for the detection of DNA by fluorescence enhancement and the following streptavidin detection by fluorescence quenching.
abstract: We reported an optical DNA/protein microfluidic sensor which consists of single stranded (ss) DNA-Cy3 probes on gold surface and simple line-shape microfluidic channel. These ssDNA-Cy3 probes with random sequence in bulk solution or on gold surface exhibits fluorescence enhancement after binding with complementary ssDNA (cssDNA) targets. Particularly it did not require complicated design or hairpin-like stem-loop conformation, which made it easier to be made and applied in analytes detection by fluorescence switching techniques. Using ssDNA-cy3 probes attached on gold surface in a microfluidic channel, strong fluorescence enhancement was measured by ssDNA with cssDNA binding or ssDNA with cssDNA-biotin binding. The following introduction of streptavidin resulted in fluorescence quenching (fluorescence decrease) because of the binding of hybridized DNA-biotin with streptavidin. This sensor showed strong affinity and high sensitivity toward the streptavidin, the minimum detectable concentration for streptavidin was 1 pM, equating to an absolute detection limit of 60 amol in this microfluidic channel. Microfluidic channel height and flow rate is optimized to increase surface reaction efficiency and fluorescence switching efficiency. In contrast to previously reported optical molecular beacon approach, this sensor can be used not only for the detection of cssDNA target, but also for the detection of streptavidin. This microfluidic sensor offers the promise of analyzing kinds of molecular targets or immunoreactions.
authors: Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya, Japan; MEXT Innovative Research Center for Preventive Medical Engineering, Nagoya University, Nagoya, Japan; Department of Chemical and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden. Electronic address: wjzyy988@gmail.com.
authors: Jun
authors: J
authors: Wang
authors: Michihiko
authors: M
authors: Aki
authors: Daisuke
authors: D
authors: Onoshima
authors: Kenji
authors: K
authors: Arinaga
authors: Noritada
authors: N
authors: Kaji
authors: Manabu
authors: M
authors: Tokeshi
authors: Shozo
authors: S
authors: Fujita
authors: Naoki
authors: N
authors: Yokoyama
authors: Yoshinobu
authors: Y
authors: Baba
mesh_terms: D015374:Biosensing Techniques / Q000379:methods; D001710:Biotin / Q000737:chemistry; D002232:Carbocyanines / Q000032:analysis*; D018076:DNA, Complementary / Q000032:analysis*; D005453:Fluorescence; D057230:Limit of Detection; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D009693:Nucleic Acid Hybridization / Q000379:methods*; D019809:Streptavidin / Q000032:analysis*
chemical_list: D002232:Carbocyanines; D018076:DNA, Complementary; C089187:cyanine dye 3; D001710:Biotin; D019809:Streptavidin
keywords: Complementary ssDNA; Fluorescence switching; Microfluidic biosensor; Streptavidin