Dataset Information

Magnetic Trapping of Bacteria at Low Magnetic Fields.

ABSTRACT: A suspension of non-magnetic entities in a ferrofluid is referred to as an inverse ferrofluid. Current research to trap non-magnetic entities in an inverse ferrofluid focuses on using large permanent magnets to generate high magnetic field gradients, which seriously limits Lab-on-a-Chip applications. On the other hand, in this work, trapping of non-magnetic entities, e.g., bacteria in a uniform external magnetic field was studied with a novel chip design. An inverse ferrofluid flows in a channel and a non-magnetic island is placed in the middle of this channel. The magnetic field was distorted by this island due to the magnetic susceptibility difference between this island and the surrounding ferrofluid, resulting in magnetic forces applied on the non-magnetic entities. Both the ferromagnetic particles and the non-magnetic entities, e.g., bacteria were attracted towards the island, and subsequently accumulate in different regions. The alignment of the ferrimagnetic particles and optical transparency of the ferrofluid was greatly enhanced by the bacteria at low applied magnetic fields. This work is applicable to lab-on-a-chip based detection and trapping of non-magnetic entities bacteria and cells.

SUBMITTER: Wang ZM

PROVIDER: S-EPMC4890591 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

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Magnetic Trapping of Bacteria at Low Magnetic Fields.

Wang Z M ZM Wu R G RG Wang Z P ZP Ramanujan R V RV

Scientific reports 20160602

A suspension of non-magnetic entities in a ferrofluid is referred to as an inverse ferrofluid. Current research to trap non-magnetic entities in an inverse ferrofluid focuses on using large permanent magnets to generate high magnetic field gradients, which seriously limits Lab-on-a-Chip applications. On the other hand, in this work, trapping of non-magnetic entities, e.g., bacteria in a uniform external magnetic field was studied with a novel chip design. An inverse ferrofluid flows in a channel ...[more]

PMID: 27254771

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Project description:The widespread use of electricity raises the question of whether or not 50 Hz (power line frequency in Europe) magnetic fields (MFs) affect organisms. We investigated the transcription of Escherichia coli K-12 MG1655 in response to extremely low-frequency (ELF) MFs. Fields generated by three signal types (sinusoidal continuous, sinusoidal intermittent, and power line intermittent; all at 50 Hz, 1 mT), were applied and gene expression was monitored at the transcript level using an Affymetrix whole-genome microarray. Bacterial cells were grown continuously in a chemostat (dilution rate D = 0.4 h-1) fed with glucose-limited minimal medium and exposed to 50 Hz MFs with a homogenous flux density of 1 mT. For all three types of MFs investigated, neither bacterial growth (determined using optical density) nor culturable counts were affected. Likewise, no statistically significant change (fold-change > 2, P ≤ 0.01) in the expression of 4,358 genes and 714 intergenic regions represented on the gene chip was detected after MF exposure for 2.5 h (1.4 generations) or 15 h (8.7 generations). Moreover, short-term exposure (8 min) to the sinusoidal continuous and power line intermittent signal neither affected bacterial growth nor showed evidence for reliable changes in transcription. In conclusion, our experiments did not indicate that the different tested MFs (50 Hz, 1 mT) affected the transcription of E. coli. A total of 60 chips are included in this study. Each comparison (treated vs. sham-treated cultures; untreated negative control cultures) consists of three replicates. The three magnetic field test conditions include sinusoidal continous, sinusoidal intermittent (2 min on, 4 min off) and power line intermittent (2 min on, 4 min off). Exposure periods were 8 min, 2.5 h, or 15 h. The response control consists of E. coli cells treated for 10 min with 1 mM H2O2 or the equivalent water volume. The negative control comprises samples taken from cultures grown with the exposure chambers swiched off.

Dataset Information

Magnetic Trapping of Bacteria at Low Magnetic Fields.

Publications

Magnetic Trapping of Bacteria at Low Magnetic Fields.

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