Abstract
Bacterial infection is a significant cause of morbidity and mortality to humans worldwide. Thus, a method for nonspecific, sensitive, and rapid enrichment of such bacteria is essential for bacteria detection and treatment. This study demonstrates a self-made core-shell Fe3O4@Polydopamine@Polyethyleneimine magnetic beads (Fe3O4@PDA@PEI MBs) with a high density positive charge-based magnetic separation scheme for the broad-spectrum rapid enrichment of microorganisms in the liquid phase. MBs with a high-density positive charge have a strong electrostatic attraction to most microorganisms in nature. Our scheme is as follows: (1) wrapping dopamine (DA) on the iron oxide through self-polymerization and wrapping PEI on the outermost shell layer in a mode of crosslinking with the PDA; (2) subsequently, the Fe3O4@PDA@PEI MBs were used to concentrate microorganisms from the sample solution; (3) performing magnetic separation and calculating the adsorption efficiency. The as-prepared Fe3O4@PDA@PEI MBs composite was carefully characterized by zeta potential analysis, Value stream-mapping (VSM), transmission electron microscopy (TEM), and Fourier transforms infrared spectrometry (FT-IR). In this study, both gram-positive and gram-negative bacteria could be captured in three minutes through electrostatic interaction. Furthermore, the adsorption efficiency on gram-negative (>98%) is higher than that on gram-positive (>95%), allowing for a simple, rapid assay to enrich organisms in resource-limited settings.
Highlights
Due to its obvious advantages of lower production cost, good efficiency and simplified operation, modified iron oxide provide a convenient method for rapid enrichment of bacteria, which is considered as a powerful means to improve early clinical intervention, food safety regulation, and environment surveillance [21–23]
We tested the magnetism of Fe3 O4 @PDA@PEI Magnetic Beads (MBs) at room temperature by vibrating the sample magnetometer (Figure 3c)
It can be seen that the whole magnetic hysteresis loops are approximatively S-shaped, and the coercivity and remanence are equal to zero, demonstrating that the prepared Fe3 O4 @PDA@PEI
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Due to its obvious advantages of lower production cost, good efficiency and simplified operation, modified iron oxide provide a convenient method for rapid enrichment of bacteria, which is considered as a powerful means to improve early clinical intervention, food safety regulation, and environment surveillance [21–23]. Some studies have shown that if iron oxide is chemically modified with chitosan [25], amino [26], vancomycin [27], or unmodified [28,29], it can be used for nonspecific separation of a variety of bacteria This non-specific separation is mainly driven by the electrostatic force between the bacteria with a negative charge and the magnetic beads with positive charge [30]. The capture efficiency of Fe3 O4 @PDA@PEI MBs on bacteria can be validated by ATP-BL method in addition to the culture-based method. Fe3 O4 @PDA@PEI MBs can achieve on-site rapid and broad-spectrum enrichment in large industries, such as medical, quarantine, environmental, agricultural, pharmaceutical, and food processing
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