Monitoring the growth and drug susceptibility of individual bacteria using asynchronous magnetic bead rotation sensors

Abstract

Continuous growth of individual bacteria has been previously studied by direct observation using optical imaging. However, optical microscopy studies are inherently diffraction limited and limited in the number of individual cells that can be continuously monitored. Here we report on the use of the asynchronous magnetic bead rotation (AMBR) sensor, which is not diffraction limited. The AMBR sensor allows for the measurement of nanoscale growth dynamics of individual bacterial cells, over multiple generations. This torque-based magnetic bead sensor monitors variations in drag caused by the attachment and growth of a single bacterial cell. In this manner, we observed the growth and division of individual E. coli bacteria, with 80 nanometer sensitivity to the cell length. Over the life cycle of a cell we observed up to 300 % increase in the rotational period of the biosensor due to increased cell volume. In addition, we observed single bacterial cell growth response to antibiotics. This work demonstrates a non-microscopy based approach for monitoring individual cell growth dynamics, including cell elongation, generation time, lag time, and division, as well as their sensitivity to antibiotics. † Corresponding authors: Raoul Kopelman kopelman@umich.edu and Brandon McNaughton bmcnaugh@umich.edu,

RETRACTED: Using silica molecular sieve modified Fe3O4 particles as supporting matrix for oxygen sensing: Construction, morphology, characterization and sensing performance

“…Some precursive efforts have reported magnetic chemosensors, such as magnetic beads and Janus sensors, which offers a perfect solution for site-specific migration [20][21][22][23][24][25][26][27]. The possibility of combining a magnetic component with oxygen sensors has been confirmed by reports from Kopelman and Klimant and their oxygen sensors based on magnetic particles [28][29][30][31][32][33][34][35][36].…”

Simultaneous and quantitative monitoring of co-cultured Pseudomonas aeruginosa and Staphylococcus aureus with antibiotics on a diffusometric platform

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Microfluidic advances in phenotypic antibiotic susceptibility testing

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