Detection of bacterial contaminants via frequency manipulation of amino-groups functionalized Fe₃O₄ nanoparticles based resonant sensor

Abstract

Bacterial infections have a large impact on public health. Through this study, we report on the development of complementary split-ring resonators (CSRR) supplemented by functionalized nanoparticles to detect bacteria in the aqueous medium. Iron oxide (Fe3O4) nanoparticles were functionalized with amino groups using (3-aminopropyl) triethoxysilane (APTES) to form (APTES@Fe3O4) nanoparticles, which have a specific affinity towards the bacterial species. This affinity was evaluated using the Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacterial species. The resonant sensor was tuned at 430 MHz and the CSRR sensor bed was further activated using APTES@Fe3O4 nanoparticles. Bacterial detection was studied over a range of concentrations from 2.66 x 109 cells to 2.66 x 108 cells. The sensor actively responded to small changes in bacterial concentration, showing an overall shift in resonance frequency of ~ 44 MHz (~ 40 MHz / cell count) for E. coli and ~ 55 MHz (50.43 MHz / cell count) for S. aureus. Dextran sulphate and Chitosan were used as the references. The magnetic character of the conjugated system exhibited strong interaction of the bacterial species with APTES@Fe3O4, justifying the high selectivity towards these species. This demonstrates the feasibility of a sensitive, fast, portable device, against the traditionally used time-consuming bio-assays.

MHz range frequency based sensor for Magnetic Particle Detection

“…The concentration studied was between 2.66x10 8 -2.66x10 9 cells. The overall frequency shift detected was between 44-55 MHz per cell count while system resonating at 430 MHz [35]. In this paper and for the purpose of this project, large amount of sample input (4mL) is provided for the LOAC device, and the sample will be amplified prior to the detection, thus there will be more than million copies of DNA in sample analyte tagged with magnetic particles.…”

MHz range frequency based sensor for Magnetic Particle Detection

“…The concentration studied was between 2.66x10 8 -2.66x10 9 cells. The overall frequency shift detected was between 44-55 MHz per cell count while system resonating at 430 MHz [35]. In this paper and for the purpose of this project, large amount of sample input (4mL) is provided for the LOAC device, and the sample will be amplified prior to the detection, thus there will be more than million copies of DNA in sample analyte tagged with magnetic particles.…”