title: Electrical sensor array for polymerase chain reaction-free messenger RNA expression profiling.
abstract: A simple and sensitive electrical sensor array for polymerase chain reaction-free (PCR-free) messenger RNA (mRNA) expression profiling is described in this work. The sensor array, consisting of vertically aligned gold microband electrode/SiO(2)/gold microband electrode sandwich structures (nanogap sensors) in orthogonal configurations, was fabricated on a 1 cm x 1 cm silicon chip. A target mRNA was first hybridized with its specific capture probes (CP) on the bottom side of the nanogap, followed by a second hybridization (annealing) of its poly(A) tail with poly(T) annealing probes (AP) on the top side of the nanogap, holding the hybridized mRNA strands vertically across the nanogap. A subsequent metallization of the hybridized mRNA strands bridged the nanogap and consequently produced a substantial change in conductance, allowing ultrasensitive detection of mRNA without any amplification. Noticeable conductance changes were observed in the presence of as little as 0.10 fM mRNA. A linear relationship between the conductance and mRNA concentration was obtained from 0.50 fM to 1.0 pM with exceptional signal intensity. As little as a 50% difference in mRNA expression was successfully detected. The sensor array also exhibited excellent mismatch discrimination due to its unique vertically aligned nanostructure and the two-step hybridization.
authors.affiliation: Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, Singapore 138669.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Chen
authors.forename: Somenath
authors.initials: S
authors.lastname: Roy
authors.forename: Yanfen
authors.initials: Y
authors.lastname: Peng
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Gao
mesh_terms: D045744:Cell Line, Tumor; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D020869:Gene Expression Profiling; D006046:Gold / Q000737:chemistry; D006801:Humans; D049329:Nanostructures / Q000737:chemistry; D009693:Nucleic Acid Hybridization; D016133:Polymerase Chain Reaction; D015347:RNA Probes / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism*; D012822:Silicon Dioxide / Q000737:chemistry
chemical_list: D015347:RNA Probes; D012333:RNA, Messenger; D006046:Gold; D012822:Silicon Dioxide