title: Optical nanosensor architecture for cell-signaling molecules using DNA aptamer-coated carbon nanotubes.
abstract: We report a novel optical biosensor platform using near-infrared fluorescent single-walled carbon nanotubes (SWNTs) functionalized with target-recognizing aptamer DNA for noninvasively detecting cell-signaling molecules in real time. Photoluminescence (PL) emission of aptamer-coated SWNTs is modulated upon selectively binding to target molecules, which is exploited to detect insulin using an insulin-binding aptamer (IBA) as a molecular recognition element. We find that nanotube PL quenches upon insulin recognition via a photoinduced charge transfer mechanism with a quenching rate of k(q) = 5.85 × 10(14) M(-1) s(-1) and a diffusion-reaction rate of k(r) = 0.129 s(-1). Circular dichroism spectra reveal for the first time that IBA strands retain a four-stranded, parallel guanine quadruplex conformation on the nanotubes, ensuring target selectivity. We demonstrate that these IBA-functionalized SWNT sensors incorporated in a collagen extracellular matrix (ECM) can be regenerated by removing bound analytes through enzymatic proteolysis. As proof-of-concept, we show that the SWNT sensors embedded in the ECM promptly detect insulin secreted by cultured pancreatic INS-1 cells stimulated by glucose influx and report a gradient contour of insulin secretion profile. This novel design enables new types of label-free assays and noninvasive, in situ, real-time detection schemes for cell-signaling molecules.
authors.affiliation: School of Mechanical Engineering, Bindley Bioscience Center, Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States.
authors.forename: Tae-Gon
authors.initials: TG
authors.lastname: Cha
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Baker
authors.forename: M Dane
authors.initials: MD
authors.lastname: Sauffer
authors.forename: Janette
authors.initials: J
authors.lastname: Salgado
authors.forename: David
authors.initials: D
authors.lastname: Jaroch
authors.forename: Jenna L
authors.initials: JL
authors.lastname: Rickus
authors.forename: D Marshall
authors.initials: DM
authors.lastname: Porterfield
authors.forename: Jong Hyun
authors.initials: JH
authors.lastname: Choi
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation*; D002460:Cell Line; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007328:Insulin / Q000032:analysis*; D007515:Islets of Langerhans / Q000378:metabolism*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D055096:Optical Devices; D051381:Rats
chemical_list: D052157:Aptamers, Nucleotide; D007328:Insulin; D037742:Nanotubes, Carbon