Increasing foodborne illnesses have led to global health
and economic
burdens. E. coli O157:H7 is one of
the most common disease-provoking pathogens and known to be lethal
Shiga toxin-producing E. coli (STEC)
strains. With a low infection dose in addition to person-to-person
transmission, STEC infections are easily spread. As a result, specific
and rapid testing methods to identify foodborne pathogens are urgently
needed. Nanozymes have emerged as enzyme-mimetic nanoparticles, demonstrating
intrinsic catalytic activity that could allow for rapid, specific,
and accurate pathogen identification in the agrifood industry. In
this study, we developed a sensitive nanoplatform based on the traditional
ELISA assay with the synergistic properties of gold and iron oxide
nanozymes, replacing the conventional enzyme horseradish peroxidase
(HRP). We designed an easily interchangeable sandwich ELISA composed
of a novel, multifunctional magneto-plasmonic nanosensor (MPnS) with
target antibodies (MPnS-Ab). Our experiments demonstrate a 100-fold
increase in catalytic activity in comparison to HRP with observable
color changes within 15 min. Results further indicate that the MPnS-Ab
is highly specific for E. coli O157:H7.
Additionally, effective translatability of catalytic activity of the
MPnS technology in the lateral flow assay (LFA) platform is also demonstrated
for E. coli O157:H7 detection. As nanozymes
display more stability, tunable activity, and multi-functionality
than natural enzymes, our platform could provide customizable, low-cost
assay that combines high specificity with rapid detection for a variety
of pathogens in a point-of-care setup.
Detection of bacterial contaminants in blood and platelet concentrates (PCs) continues to be challenging in clinical settings despite available current testing methods. At the same time, it is important to detect the low bacterial contaminants present at the time of transfusion. Herein, we report the design and synthesis of a dual-modal magnetofluorescent nanosensor (MFnS) by integrating magnetic relaxation and fluorescence modalities for the wide-range detection of blood-borne pathogens. In this study, functional MFnSs are designed to specifically detect Staphylococcus epidermidis and Escherichia coli, two of the predominant bacterial contaminants of PCs. Specific interaction between the target pathogen and functional MFnS resulted in the change of water proton's magnetic relaxation time, indicative of sensitive detection of the target bacteria from low to high colony-forming units (CFUs). In addition, the acquired magnetic relaxation signal of the MFnS further facilitated quantitative assessment of the slow and fast growth kinetics of target pathogens. Moreover, the presence of fluorescence modality in MFnS allowed for the detection of multicontaminants. Bacterial detection was also performed in complex media including whole blood and PCs, which further demonstrated its robust detection sensitivity. Overall, our study indicated that the designer MFnS will have potential for the wide-range detection of blood-borne pathogens and features desirable qualities including timeliness, sensitivity, and specificity.
The application of solvent and catalyst free, green chemistry approaches is highly desired. Herein we have explored a facile, one-step “Click-ene” chemistry for the synthesis of functional monomers and macromolecules.
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