Highly sensitive detection of bacteria (E. Coli) endotoxin using novel PANI-benzimidazole-Ag nanocomposite by DMMB dye displacement assay

Abstract In the present study, a new biochemical biosensor material of conductive Silver (Ag) reinforced polyaniline (PANI)-Benzimidazole copolymer nanocomposite was fabricated via in situ chemical oxidative polymerization method for the detection of endotoxin. The fabricated PANI-Benz-Ag nanocomposite was characterized by FTIR, XRD, UV–visible spectrometer, DSC, TGA, Zeta-potential, SEM, TEM, and Confocal fluorescence imaging microscopy. The measured particle size, zeta-potential, and conductivity of the PANI-Benz-Ag nanocomposite were 4.942 nm, −10.4 mV, and 73.7 μS cm−1 respectively. The crystallite size of Ag nanoparticles was around 67 nm calculated by XRD analysis and TGA analysis was carried out to determine weight loss and thermal stabilities of PANI-Benz and PANI-Benz-Ag nanocomposite. The endotoxin (E. coli) bacteria detection ability of the synthesized PANI-Benz-Ag nanocomposite-based biochemical biosensor using DMMB dye displacement assay through the hitchhiking method by confocal fluorescence microscopy was found to be simple and effective. Endotoxin (E. coli) can form a stable interaction with other bioactive molecules and thus it binds readily with Ag-doped PANI-Benzimidazole nanocomposite. Further, the DMMB dye displacement assay method is more accurate and sensitive than the other existing methods for the detection of endotoxin.