Electrochemical Detection of Waterborne Bacteria Using Bi-Functional Magnetic Nanoparticle Conjugates

Abstract

Detection of microbial contamination in water is imperative to ensure water quality. We have developed an electrochemical method for the detection of E. coli using bi-functional magnetic nanoparticle (MNP) conjugates. The bi-functional MNP conjugates were prepared by terminal-specific conjugation of anti-E. coli IgG antibody and the electroactive marker ferrocene. The bi-functional MNP conjugate possesses both E. coli-specific binding and electroactive properties, which were studied in detail. The conjugation efficiency of ferrocene and IgG antibodies with amine-functionalized MNPs was investigated. Square-wave voltammetry enabled the detection of E. coli concentrations ranging from 101–107 cells/mL in a dose-dependent manner, as ferrocene-specific current signals were inversely dependent on E. coli concentrations, completely suppressed at concentrations higher than 107 cells/mL. The developed electrochemical method is highly sensitive (10 cells/mL) and, coupled to magnetic separation, provides specific signals within 1h. Overall, the bi-functional conjugates serve as ideal candidates for electrochemical detection of waterborne bacteria. This approach can be applied for the detection of other bacteria and viruses.

Recent Developments in Innovative Magnetic Nanoparticles-Based Immunoassays: From Improvement of Conventional Immunoassays to Diagnosis of COVID-19

“…The Bradford method, which utilizes dye binding to the target protein and subsequent colorimetric monitoring, is the classical protein estimation method [37]. It has been widely adopted in various antibody-conjugated MNPs [38][39][40][41][42] and the antibody-binding efficiency was verified up to 94.5% [7].…”

Magnetic Nanoseparation Technology for Efficient Control of Microorganisms and Toxins in Foods: A Review

“…Gunasekaran et al successfully combined immunomagnetic separation with electrochemical detection to prepare a bifunctional MNP conjugate (Fc-MNP-IgG) with electroactive label ferrocene and antibody for the electrochemical detection of E. coli. The developed electrochemical method has a sensitivity of up to 10 cells/mL within 1 h. 118 Wilson et al developed a sensitive, rapid, and low-cost electrochemical detection method for the detection and quantification of E. coli, S. aureus, and S. typhimurium in potable water and apple juice. The method is based on electrical impedance spectroscopy measurements, melittinfunctionalized nanoparticles for biometric identification, silver screen-printed interdigital electrodes for monitoring changes in capacitance, and EIS for the transduction process (Figure 3B).…”

“…coli. The developed electrochemical method has a sensitivity of up to 10 cells/mL within 1 h . Wilson et al developed a sensitive, rapid, and low-cost electrochemical detection method for the detection and quantification of E.…”

Advances in miniaturized nanosensing platforms for analysis of pathogenic bacteria and viruses

“…Different analytical technologies have been exploited to develop these analytical and bioanalytical devices such as chromatography, [6][7][8] spectroscopy, [9][10][11][12][13][14][15][16][17][18][19] electrophoresis, [20][21][22][23][24][25][26][27] immunoassay, [28][29][30][31][32][33][34][35] and electrochemistry. [36][37][38][39][40][41] However, accurate and selective determination of such microorganisms is usually performed by coupling different analytical methodologies to achieve the optimum analysis. For instance, several POC diagnostic biosensors are based on using electrochemical systems for sensing the pathogens using immunoassay techniques for accurate and specific analysis.…”