title: Silicon-based biosensors for rapid detection of protein or nucleic acid targets.
abstract: BACKGROUND
  We developed a silicon-based biosensor that generates visual, qualitative results or quantitative results for the detection of protein or nucleic acid targets in a multiplex format.
  
  
  METHODS
  Capture probes were immobilized either passively or covalently on the optically coated surface of the biosensor. Intermolecular interactions of the immobilized capture probe with specific target molecules were transduced into a molecular thin film. Thin films were generated by enzyme-catalyzed deposition in the vicinity of the surface-bound target. The increased thickness on the surface changed the apparent color of the biosensor by altering the interference pattern of reflected light.
  
  
  RESULTS
  Cytokine detection was achieved in a 40-min multiplex assay. Detection limits were 4 ng/L for interleukin (IL)-6, 31 ng/L for IL1-beta, and 437 ng/L for interferon-gamma. In multianalyte experiments, cytokines were specifically detected with signal-to-noise ratios ranging from 15 to 80. With a modified optical surface, specificity was also demonstrated in a nucleic acid array with unambiguous discrimination of single-base changes in a 15-min assay. For homozygous wild-type and homozygous mutant samples, signal-to-noise ratios of approximately 100 were observed. Heterozygous samples yielded approximately equivalent signals for wild-type and mutant capture probes.
  
  
  CONCLUSIONS
  The thin-film biosensor allows rapid, sensitive, and specific detection of protein or nucleic acid targets in an array format with results read visually or quantified with a charge-coupled device camera. This biosensor is suited for multianalyte detection in clinical diagnostic assays.
authors.affiliation: ThermoBioStar, Inc., 6655 Lookout Rd., Boulder, CO 80301, USA.
authors.forename: R
authors.initials: R
authors.lastname: Jenison
authors.forename: H
authors.initials: H
authors.lastname: La
authors.forename: A
authors.initials: A
authors.lastname: Haeberli
authors.forename: R
authors.initials: R
authors.lastname: Ostroff
authors.forename: B
authors.initials: B
authors.lastname: Polisky
mesh_terms: D015374:Biosensing Techniques; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics; D004247:DNA / Q000032:analysis; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis; D007375:Interleukin-1 / Q000032:analysis; D015850:Interleukin-6 / Q000032:analysis; D009696:Nucleic Acids / Q000032:analysis*; D020641:Polymorphism, Single Nucleotide; D011506:Proteins / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017655:Silicon Compounds
chemical_list: C505032:CFTR protein, human; D007375:Interleukin-1; D015850:Interleukin-6; D009696:Nucleic Acids; D011506:Proteins; D017655:Silicon Compounds; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D007371:Interferon-gamma; D004247:DNA; C032734:silicon nitride