title: Disposable immunosensors for C-reactive protein based on carbon nanotubes field effect transistors.
abstract: Label-free immunosensors based on single-walled carbon nanotubes field effect transistor (NTFET) devices were developed for the detection of C-reactive protein (CRP) which is currently the best validated inflammatory biomarker associated with cardiovascular diseases. The immunoreaction principle consists in the direct adsorption of CRP specific antibodies (anti-CRP) to single-walled carbon nanotubes (SWCNTs) networks. Such anti-CRP are the molecular receptors of CRP antigens which, in turn, can be detected by the developed NTFET devices in a linear dynamic range of 10(-4)-10(2) μg/mL. Thus, typical values of CRP (in blood serum) for healthy persons (<1 μg/mL), and higher levels (>5 μg/mL) corresponding to pathological states, can be both detected with the NTFET immunosensors, becoming an advantageous alternative as the basis for the development of analytical instrumentation for assessment of risk of occurrence of cardiovascular diseases. A log-log linear regression was applied to the experimental data with a correlation coefficient of r=0.9962 (p<0.001), and there is no statistical difference (from ANOVA) between individual NTFET devices (p=0.9582), demonstrating acceptable reproducibility. According to the experimental results, the estimate of detection limit (LOD, 10(-4)μg/mL) is 3-fold lower than that of some conventional immunoassay techniques for blood serum (e.g., LOD of 0.2 μg/mL for high-sensitivity enzyme-linked immunosorbent assay), and the dynamic range (10(-4)-10(2)μg/mL) is about 6-fold higher. Furthermore, this simple and low-cost methodology allows the use of sample volumes as low as 1 μL for the label-free detection of CRP.
authors.affiliation: Department of Chemistry & CESAM, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal. celinejustino@ua.pt
authors.forename: Celine I L
authors.initials: CI
authors.lastname: Justino
authors.forename: Ana C
authors.initials: AC
authors.lastname: Freitas
authors.forename: José P
authors.initials: JP
authors.lastname: Amaral
authors.forename: Teresa A P
authors.initials: TA
authors.lastname: Rocha-Santos
authors.forename: Susana
authors.initials: S
authors.lastname: Cardoso
authors.forename: Armando C
authors.initials: AC
authors.lastname: Duarte
mesh_terms: D000906:Antibodies / Q000737:chemistry*; D015415:Biomarkers / Q000032:analysis; D002097:C-Reactive Protein / Q000032:analysis* / Q000276:immunology; D004867:Equipment Design; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods; D037742:Nanotubes, Carbon / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D014173:Transistors, Electronic
chemical_list: D000906:Antibodies; D015415:Biomarkers; D037742:Nanotubes, Carbon; D002097:C-Reactive Protein