Single-walled carbon nanotube chemoresistive label-free immunosensor for salivary stress biomarkers (original) (raw)
Related papers
In the present work, we report characterization studies of antigen(Ag)-antibody (Ab) interaction based on the multi-walled carbon nanotube array-modified gold electrode for label-free electrochemical immunosensor.-COOH functionalization of MWCNT was suggested by FTIR spectroscopy. Images from atomic force microscopy (AFM) and RAMAN spectroscopy confirmed the interaction of Ab on the gold interface based on the MWCNT array. A cyclic voltammetric study exhibited a linear response in phosphate buffered saline (PBS) solution including 1mM K3Fe (CN) 6 at pH 7.4 with PSA concentrations over a range of 2 to 40 ngmL-1 , and a calculated detection limit of 0.56 ngmL-1 .
Controllable gold nanoparticle deposition on carbon nanotubes and their application in immunosensing
A CNT–AuNPs hybrid nanocomposite platform was prepared from nanodisperse AuNPs in N-[3(trimethoxysilyl)propyl]ethylenediamine (EDAS) sol–gel matrices with purified MWCNT. EDAS, an amine group-containing sol–gel solution, was utilized for its ability to stabilize the nanoparticles in solution. The developed model system was based on immobilized rabbit anti-mouse IgG-HRP (horseradish peroxidase) for reagentless detection of mouse IgG. The immunosensing platform was prepared by using Nafion for the immobilization of rabbit anti-mouse IgG-HRP and CNT–AuNPs hybrid nanocomposite on a glassy carbon electrode used for the detection of mouse IgG which provides a biocompatible microenvironment. The resulting CNT–AuNPs nanocomposite brings new capabilities for electrochemical devices by using the synergistic action of its electrocatalytic activity. The CNT–AuNPs were characterized using SEM, TEM, EIS, and AFM, and the analytical performance was monitored by differential pulse voltammetry. The detection limit of mouse IgG is 0.5 ng mL 1 (S/N ratio ¼ 3). In addition, the immunosensor efficiently allowed a specific electrochemical analysis of mouse IgG and easy discrimination of goat IgG, chicken IgG, and rabbit IgG.
We demonstrate a label-free peptide-coated carbon nanotube-based immunosensor for the direct assay of human serum. A rheumatoid arthritis (RA)-specific (cyclic citrulline-containing) peptide, was immobilized to functionalized single-walled carbon nanotubes deposited on a quartz crystal microbalance (QCM) sensing crystal. Serum from RA patients was used to probe these nanotube-based sensors, and antibody binding was detected by QCM sensing. Specific antibody binding was also determined by comparing the assay of two serum control groups (normal and diseased sera), and the native unmodified peptide. The sensitivity of the nanotube-based sensor (detection in the femtomol range) was higher than that of the established ELISA and recently described microarray assay systems, detecting 34.4 and 37.5% more RA patients with anti-citrullinated peptide antibodies than those found by ELISA and microarray, respectively. There was also an 18.4 and 19.6% greater chance of a negative test being a true indicator of a person not having RA than by either ELISA or microarray, respectively. The performance of our label-free biosensor enables its application in the direct assay of sera in research and diagnostics.