A recent approach in disease diagnosis and viral epidemics is aimed at
point-of-care tests that could be administered near the patient rather than
time-consuming processes involving centralized laboratories. Point-of-care
devices provide rapid results in simple and low-cost manner requiring only
small sample volumes. These devices will strongly benefit from advanced
materials and fabrication methods to improve their efficiency and
sensitivity. We report a functionalized carbon nanotube label for an
immunosensor application. Carbon nanotube label was prepared by modifying
the carbon nanotube surface to anchor biomolecules. First, the carboxylic
acid treated multi-walled carbon nanotubes (MWCNTs) were uniformly dispersed
with polyvinylpyrrolidone (PVP) by sonication in aqueous solution. PVP
partially wraps around the carbon nanotubes and exposes the surface of the
nanotubes for further functionalization. The MWCNTs were then conjugated
with human immunoglobulin G (IgG) using EDC/Sulfo-NHS coupling chemistry,
where the antibodies occupied sites not covered by PVP. The dispersion,
surfactant modification, and antibody conjugation of the MWCNTs were also
confirmed using SEM and TEM images. The successful functionalization of the
MWCNTs and reactivity of the covalent attached antibodies were demonstrated
for specific antigen binding on the microelectrode device. The carbon
nanotube-based detection mechanism could be tailored for screening various
analyte specific molecules. Furthermore, the reported technique could easily
be integrated in various microfluidic and lab-on-a-chip devices for the
development of functional electronic sensors providing quantitative,
sensitive, and low-cost detection in pointof- care setup.