Gold Nanoparticle and PCR-Based Colorimetric Assay for the Identification of Campylobacter spp. in Chicken Carcass

Campylobacteriosis is a common cause of gastrointestinal disease. In this study, we suggest a general strategy of applying gold nanoparticles in colorimetric biosensors to detect Campylobacter in chicken carcass. Polymerase chain reaction (PCR) was utilized for the amplification of the target genes, and the thiolated PCR products were collected. Following the blending of colloid gold nanoparticles (AuNPs) with PCR products, the thiol bound to the surface of AuNPs, forming gold nanoparticle-PCR (GNP-PCR) products. The PCR products had a sufficient negative charge, which enabled AuNPs to maintain a dispersed formation under electrostatic repulsion. This platform presented a color change as gold nanoparticles aggregate. It did not need additional time and optimization of pH for PCR amplicons to adhere to the gold nanoparticles. The specificity of gold nanoparticles of modified primer pairs for mapA from C. jejuni and ceuE from C. coli was activated perfectly (C. jejuni, P-value: 0.0085; C. coli, P-value: 0.0239) when compared to Salmonella Enteritidis and Escherichia coli as non-Campylobacter species. Likewise, C. jejuni was successfully detected from artificially contaminated chicken carcass samples. According to the sensitivity test, at least 15 ng/μL of Campylobacter PCR products or 1×10³ CFU/ml of cells in the broth was needed for the detection using the optical method.