title: Functionalized SnO₂ nanobelt field-effect transistor sensors for label-free detection of cardiac troponin.
abstract: Real-time label-free electrical detection of proteins, including cardiac troponin (cTn), is demonstrated using functionalized SnO₂ nanobelt field-effect transistors (FETs) with integrated microfluidics. Selective biomolecular functionalization of the active SnO₂ nanobelt channel and effective passivation of the substrate surface were realized and verified through fluorescence microscopy. The validation/verification of the sensing scheme was initially demonstrated via detection of biotin-streptavidin binding: devices with single biotinylated SnO₂ nanobelts showed pronounced conductance changes in response to streptavidin binding. Importantly, the pH-dependence of the conductance changes was fully consistent with the charged states of streptavidin at different pH. Moreover, the specificity of the sensors' electrical responses was confirmed by co-labeling with quantum dots. Finally, the sensing platform was successfully applied for detection of the cardiac troponin I (cTnI) subunit within cTn, a clinically important protein marker for myocardial infarction.
authors.affiliation: Department of Physics and Integrative NanoScience Institute, Florida State University, Tallahassee, FL 32306, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cheng
authors.forename: Kan-Sheng
authors.initials: KS
authors.lastname: Chen
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Meyer
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.forename: Linda S
authors.initials: LS
authors.lastname: Hirst
authors.forename: P Bryant
authors.initials: PB
authors.lastname: Chase
authors.forename: Peng
authors.initials: P
authors.lastname: Xiong
mesh_terms: D000818:Animals; D055910:Antibodies, Immobilized; D015415:Biomarkers / Q000032:analysis; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D001710:Biotin; D002417:Cattle; D004867:Equipment Design; D006801:Humans; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry; D008856:Microscopy, Fluorescence; D009203:Myocardial Infarction / Q000175:diagnosis / Q000378:metabolism; D009206:Myocardium / Q000737:chemistry; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000032:analysis; D019809:Streptavidin; D017971:Tin Compounds; D014173:Transistors, Electronic; D014335:Tropomyosin / Q000032:analysis; D019210:Troponin I / Q000032:analysis* / Q000276:immunology
chemical_list: D055910:Antibodies, Immobilized; D015415:Biomarkers; D017971:Tin Compounds; D014335:Tropomyosin; D019210:Troponin I; D012710:Serum Albumin, Bovine; D001710:Biotin; D019809:Streptavidin; C045358:stannic oxide