3.2. Label-free impedance immunosensor using gold nanoparticles
for characterization of Brucella melitensis
The impedance method is one more quick and cheap substition for those
methods using label-free biosensors (Wu et
al., 2013). Most of these sensors are label-dependent that require
labeling of bio-molecules to convert the antibody/antigen interaction
into detectable electrochemical signals. In contrast, label-free
impedance immunosensors show outstanding advantages such as speed,
cheapness and ease of operation (Varshney,
Li, Srinivasan, & Tung, 2007).
Wu et al. designed a label-free impedance immunosensor based on the gold
nanoparticles with modified screen-printed carbon electrodes (GNP-SPCEs)
for rapid detection of Brucella melitensis. Cyclic voltammetry
(CV) and electrochemical impedance spectroscopy (EIS) were utilized to
characterize interaction of the Brucella melitensis antigens on
the surface of GNP-SPCEs against antibody molecules. This designed
biosensor was able to detect 1 × 104 and 4 ×
105 CFU/mL of Brucella melitensis in pure
culture and milk samples in less than 1.5 h, respectively
(Wu et al., 2013).