title: Direct quantification of analyte concentration by resonant acoustic profiling.
abstract: BACKGROUND
  Acoustic sensors that exploit resonating quartz crystals directly detect the binding of an analyte to a receptor. Applications include detection of bacteria, viruses, and oligonucleotides and measurement of myoglobin, interleukin 1beta (IL-1beta), and enzyme cofactors.
  
  
  METHODS
  Resonant Acoustic Profiling was combined with a microfluidic lateral flow device incorporating an internal reference control, stable linker chemistry, and immobilized receptors on a disposable sensor "chip". Analyte concentrations were determined by analyzing the rate of binding of the analyte to an appropriate receptor.
  
  
  RESULTS
  The specificity and affinity of antibody-antigen and enzyme-cofactor interactions were determined without labeling of the receptor or the analyte. We measured protein concentrations (recombinant human IL-1beta and recombinant human myoglobin) and quantified binding of cofactors (NADP+ and NAD+) to the enzyme glucose dehydrogenase. Lower limits of detection were approximately 1 nmol/L (17 ng/mL) for both IL-1beta and human myoglobin. The equilibrium binding constant for NADP+ binding to glucose dehydrogenase was 2.8 mmol/L.
  
  
  CONCLUSIONS
  Resonant Acoustic Profiling detects analytes in a relatively simple receptor-binding assay in <10 min. Potential applications include real-time immunoassays and biomarker detection. Combination of this technology platform with existing technologies for concentration and presentation of analytes may lead to simple, label-free, high-sensitivity methodologies for reagent and assay validation in clinical chemistry and, ultimately, for real-time in vitro diagnostics.
authors.affiliation: Akubio Ltd., Cambridge, United Kingdom.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Godber
authors.forename: Kevin S J
authors.initials: KS
authors.lastname: Thompson
authors.forename: Marian
authors.initials: M
authors.lastname: Rehak
authors.forename: Yildiz
authors.initials: Y
authors.lastname: Uludag
authors.forename: Sven
authors.initials: S
authors.lastname: Kelling
authors.forename: Alexander
authors.initials: A
authors.lastname: Sleptsov
authors.forename: Mark
authors.initials: M
authors.lastname: Frogley
authors.forename: Klaus
authors.initials: K
authors.lastname: Wiehler
authors.forename: Christopher
authors.initials: C
authors.lastname: Whalen
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Cooper
mesh_terms: D000162:Acoustics; D000818:Animals; D000918:Antibody Specificity; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D042843:Glucose 1-Dehydrogenase / Q000032:analysis*; D006801:Humans; D007375:Interleukin-1 / Q000032:analysis*; D051379:Mice; D046210:Microfluidic Analytical Techniques / Q000379:methods; D009211:Myoglobin / Q000032:analysis*; D009243:NAD / Q000032:analysis; D009249:NADP / Q000032:analysis; D011994:Recombinant Proteins / Q000032:analysis; D012680:Sensitivity and Specificity; D013379:Substrate Specificity; D013499:Surface Properties; D013997:Time Factors
chemical_list: D007375:Interleukin-1; D009211:Myoglobin; D011994:Recombinant Proteins; D009243:NAD; D009249:NADP; D042843:Glucose 1-Dehydrogenase