interaction with the bacteria that

interaction with the bacteria that have a negative charge onits surface at pH > 4.5. The AF-MNPs are applicable as acoagulant and capture agent for the bacteria in a wide pH(5.0-8.0) range.Comparison of the Present AF-MNPs Based Methodwith Other Methods for Bacteria Capture. A comparison ofthe present method with other methods for capturing bacteriaby functional MNPs in terms of amount of MNPs, captureefficiency, and incubation time is made in Table 1, revealingthe advantages of the present method, such as no need forfurther modification with biomolecules, shorter incubationtime, and high capture efficiency.Removal of Bacteria in Real Samples. We employed amicrobial plate count method (25) to further investigate thetrapping capability of the AF-MNPs toward Gram-positiveand Gram-negative bacteria in water, beverage, and urinesamples. Anionic silica coated MNPs were used as control.AF-MNPs were allowed to interact with their target bacteriafor 10 min. The resulting conjugates were then separatedand diluted, and cultured on a LB plate for 24 h at 37 °C. Theresults of the magnetic capture assays for AF-MNPs and silicacoated MNPs are shown in Figure S8. AF-MNPs show efficientcapture capability in water, beverage, and urine samples.Bacterial cells are removed by AF-MNPs with an efficiencyof 88.5-99.1% in the studied water, beverage and urinesamples. As the control, silica coated MNPs show much lessefficiency than AF-MNPs for bacteria removal.In conclusion, we have reported a simple method forrapid and efficient capture of bacterial pathogens based onAF-MNPs. Although amino-group offers less specificity/selectivity than antibodies, AF-MNPs are attractive forcapturing a wide range of bacteria.