Detection of Escherichia coli in pharmaceutical and water samples using a biosensor based on carbon nanotubes containing gold nanoparticles

Escherichia coli is an important indicator in the quality control of pharmaceutical and real samples. This study compares the detection of this bacterium by regular method and a biosensor based on Multi-Walled Carbon Nanotubes (MWCNTs) on glassy carbon electrodes (GCE) in pharmaceutical and water as real sample.

In this experimental study, the conventional culture method (pour plate) and modified biosensor based on Multi-Walled Carbon Nanotubes on glassy carbon electrode with the arrangement of GC/MWCNTs/AuNPs/Ab/BSA were used for the detection of E. coli. Dilutions of E. coli between (1 ×101–1×108 CFU/ml) were used in pharmaceutical and water samples, prepared in 0.1 M PBS (pH 7.4), mixed with 0.5mM acetaminophen. The efficiency of the designed biosensor was investigated using SEM, Cyclic Voltammetry, and Square-Wave Voltammetry electrochemical techniques, as well as interfering bacteria.

The results of E. coli detection using the conventional culture and designed biosensor were not statistically significant. The designed biosensor had a high sensitivity with accuracy in 3 minutes and LOD 3.02 CFU/ml for Escherichia coli.

Considering the time-consuming and influenced by environmental factors in the microbial monitoring of pharmaceuticals for E. coli detection in conventional methods and the risk of losing pharmaceutical products, the biosensor has good efficiency in detection with low cost and no need for enrichment in a small volume of samples.