Background: Today, nanoparticles hold great promise in biomedical researches and applications
including bacteria detection. The rapid and sensitive outcomes of bacteria detection strategies
using nanoparticle conjugates become determinative, especially in bacterial outbreaks. In the
current research, we focused on detecting V. cholera bacteria and its toxin using a thiocyanate/Au
nanoparticle. Thiocyanate adsorbed strongly on the surface of gold nanoparticles and changed the
surface by enhancing surface plasmon resonance of gold nanoparticles.
Objective: This method is tried to introduce a simple and fast procedure to assay vibrio cholera. So, it
is observed by the naked eyes as well.
Methods: We used two antibodies (Ab) for V. cholera detection: a) a primary antibody conjugated to
magnetic nanoparticles (MNPs) for trapping V. cholera bacterial cells, and b) a secondary Abconjugated
thiocyanate-GNPs as a colorimetric detector. Then, an immuno-magnetic separation system
connected to a colorimetric assay was designed based on the GNPs. The results were measured
by ultraviolet-visible (UV-Vis) spectroscopy.
Results: The results showed that gold nanoparticles are an appropriate optical assay for detecting
biological samples in a minimum concentration and also it can be easily seen by the naked eyes. The
linear range of this biosensor is 3.2×104 to 28×104 cells per ml.
Conclusion: In this research, a colorimetric immune assay based on gold nanoparticles was designed
to improve the sensitivity of V. cholera detection. Also, this method can be used for the detection of
other biological agents.