Abstract
PANI-Ag-Fe nanocomposite thin films based electrochemical E. coli sensor was developed with thermal annealing. PANI-Ag-Fe nanocomposite thin films were prepared by oxidative polymerization of aniline and the reduction process of Ag-Fe bimetallic compound with the presence of nitric acid and PVA. The films were deposited on glass substrate using spin-coating technique before they were annealed at 300°C. The films were characterized using XRD, UV-Vis spectroscopy, and FESEM to study the structural and morphological properties. The electrochemical sensor performance was conducted using I-V measurement electrochemical impedance spectroscopy (EIS). The sensitivity upon the presence of E. coli was measured in clean water and E. coli solution. From XRD analysis, the crystallite sizes were found to become larger for the samples after annealing. UV-Vis absorption bands for samples before and after annealing show maximum absorbance peaks at around 422 nm–424 nm and 426 nm–464 nm, respectively. FESEM images show the diameter size for nanospherical Ag-Fe alloy particles increases after annealing. The sensor performance of PANI-Ag-Fe nanocomposite thin films upon E. coli cells in liquid medium indicates the sensitivity increases after annealing.
Highlights
Escherichia coli (E. coli) bacteria can be found in contaminated water and food
E. coli is being widely chosen as an indicator species of bacteria since it is fecal coliform bacteria that are specific to the intestines of human and other warmblooded animals but not normally pathogenic, it is easy to detect and culture and it is found at higher concentrations than other pathogens in waters [1]
Various compositions of Ag-Fe alloy nanoparticles were synthesized to study the optimum composition for the sensor to perform high sensitivity
Summary
Escherichia coli (E. coli) bacteria can be found in contaminated water and food. E. coli are harmless and cause relatively brief diarrhea. A few nasty strains such as E. coli O157:H7 can cause severe abdominal cramps, bloody diarrhea, and vomiting. To detect E. coli in water, biosensors which offer simple, rapid, sensitive, and selective detection method for analysis of environmental contaminants are highly required. Three common types of biosensors have been developed for bacteria determination based on electrochemical [2,3,4], optical [5, 6], piezoelectric [7, 8] detection. Electrochemical biosensors are based on selective interaction between target analyte and recognition element, including potentiometric, voltammetric, amperometric, and electrochemical impedance spectroscopy biosensors. The interaction can produce an electrical signal that is related to the concentration of the analyte being studied [9]
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