Tunable Magneto-Plasmonic Nanosensor for Sensitive Detection of Foodborne Pathogens

Abstract

Frequent outbreaks of food-borne pathogens, particularly E. coli O157:H7, continue to impact human health and the agricultural economy tremendously. The required cell count for this pathogenic strain of E. coli O157:H7 is relatively low and hence it is vital to detect at low colony forming unit (CFU) counts. Available detection methods, though sensitive, fall short in terms of timeliness and often require extensive sample processing. To overcome these limitations, we propose a novel magneto-plasmonic nanosensor (MPnS) by integrating surface plasmon resonance (SPR) properties with spin–spin magnetic relaxation (T2 MR) technology. We engineered MPnS by encapsulating several gold nanoparticles (GNPs) within the polymer-coating of iron oxide nanoparticles (IONPs). First, the polyacrylic acid (PAA)-coated IONPs were synthesized using a solvent precipitation method, then gold chloride solution was used to synthesize GNPs and encapsulate them within the PAA-coatings of IONPs in one step. A magnetic separation technique was used to purify the MPnS and the presence of GNPs within IONPs was characterized using transmission electron microscopy (TEM), energy dispersive x-ray spectroscopy (EDS), and other spectroscopic methods. The synthesized MPnS exhibits MR relaxation properties while possessing amplified optical properties than conventional GNPs. This allows for rapid and ultrasensitive detection of E. coli O157:H7 by SPR, T2 MR, and colorimetric readout. Experiments conducted in simple buffer and in milk as a complex media demonstrated that our MPnS-based assay could detect as low as 10 CFUs of this pathogenic strain of E. coli O157:H7 in minutes with no cross-reactivity. Overall, the formulated MPnS is robust and holds great potential for the ultrasensitive detection of E. coli O157:H7 in a simple and timely fashion. Moreover, this platform is highly customizable and can be used for the detection of other foodborne pathogens.

Review on emerging applications of nanobiosensor in food safety

“…By means of a combination of fluorescence measurements and magnetic relaxation measurements this method identified different types of food pathogens in industries. Multiparametric magnetofluorescent nanosensors (MfnS) and magneto-plasmonic nanosensor (MPnS) speedily detected pathogenic E. coli O157:H7 (Banerjee et al, 2016(Banerjee et al, , 2017(Banerjee et al, , 2023. Varshney et al (2005Varshney et al ( , 2007 developed magnetic nanoparticle attached antibody conjugates to capture E. coli O157:H7 in ground beef samples.…”

“…By means of a combination of fluorescence measurements and magnetic relaxation measurements this method identified different types of food pathogens in industries. Multiparametric magneto‐fluorescent nanosensors (MfnS) and magneto‐plasmonic nanosensor (MPnS) speedily detected pathogenic E. coli O157:H7 (Banerjee et al., 2016, 2017, 2023). Varshney et al.…”

Electrochemical and optical-based systems for SARS-COV-2 and various pathogens assessment

“…Banerjee et al [81] demonstrated the magneto-plasmonic nanosensor (MPnS) by merging spin-spin magnetic relaxation (T2 MR) with SPR characteristics for the monitoring of E. coli O157:H7. N-hydroxy succinimide/1-ethyl-3-[3-(dimethylamino) propyl] carbodiimide hydrochloride (NHS/ EDC) chemistry was used to improve the properties of MPnS with distinct antibodies for the target pathogen on the top of biosensors to identify E. coli O157:H7.…”