Jaan Mannik

Associate Professor

UT

Research

I am carrying out research at the interface of biophysics and nanotechnology. The main theme of my research is to understand at molecular level how self5 organizing processes take place in prokaryotic cells. The questions I address are: How prokaryotic cells position proteins? What is the role of DNA as a structural scaffold in bacterial cell? How does bacterial DNA segregate? How do mechanical forces affect growth and properties of bacterial cell wall? I am interested in finding quantitative answers to these questions and explaining underlying processes based on models of statistical mechanics, polymer physics and theory of elasticity.

In experiment, I am using fluorescent microscopy of fusion proteins to infer information about molecular processes in bacterial cell. I combine microscopy with quantitative image analysis to resolve structures below a diffraction limit. I study E. coli as model system – new “hydrogen atom” for many physicists. Few years ago I and my co-workers at TU Delft discovered that these bacteria transform from a regular rod-shaped phenotype to very irregular and large cells when they grow squeezed in narrow channels on a silicon chip. Remarkably, these ‘squeezed’ bacteria are still able to robustly carry out chromosome segregation, cell division and other cellular functions despite their very irregular shapes and huge sizes. I continue to be interested in these curious E. coli to understand how bacterial cells are able to organize their components when their geometry is strongly perturbed.

In addition to experimenting with cells, a significant part of my research effort goes to designing lab-on-a-chip devices. My main interest are microfluidic structures which allow carry out high resolution microscopy of bacteria over many cell cycles and at the same time maintain a physiological environment for these cells. I am also interested in building electrical and mechanical actuators on these chips to interface with cells.

Lab Website

Education

• PhD: Physics - STONY BROOK UNIVERSITY, STONY BROOK, NY, (2003)
• MS: Physics - UNIVERSITY OF TARTU, TARTU, ESTONIA (1996)
• BS: Physics - UNIVERSITY OF TARTU, TARTU, ESTONIA (1994)

Publications

Influence of electrolyte composition on liquid-gated carbon-nanotube and graphene transistors, I. Heller, S. Chatoor, J. Männik, M. A. G. Zevenbergen, C. Dekker, and S. G. Lemay, J. Am. Chem. Soc. 132 (2010) 17149.

Charge Noise in Graphene Transistors, I. Heller, S. Chatoor, J. Männik, M. A. G. Zevenbergen, J. B. Oostinga, A. F. Morpurgo, C. Dekker, and S. G. Lemay, Nano Lett. 10 (2010) 1563.

Bacterial growth and motility in sub-micron constrictions, J. Männik, R. Driessen, J. E. Keymer and C. Dekker, Proc. Natl. Acad. Sci. U. S. A. 106 (2009) 14861. The article is PNAS cover article of Sep. 1, 2009 issue. The paper has also been reviewed in Science Daily, Nanowerk and several other websites covering news in science.

Comparing weak and strong gate-coupling regimes for nanotube and graphene transistors, I. Heller, S. Chatoor, J. Männik, M. A. G. Zevenbergen, C. Dekker, and S. G. Lemay, Phys. Stat. Sol. 3 (2009) 190.

Optimizing the signal-­--to-­--noise ratio for biosensing with carbon nanotube transistors, I. Heller, J. Männik, S. G. Lemay and C. Dekker, Nano Lett. 9 (2009) 377.

Charge Noise in Liquid-­--Gated Single-­--Wall Carbon Nanotube Transistors, J. Männik, I. Heller, A. M. Jannsens, S. G. Lemay and C. Dekker, Nano Lett. 8 (2008) 685.

Identifying the Mechanism of Biosensing with Carbon Nanotube Transistors, I. Heller, A. M. Jannsens, J. Männik, E. D. Minot, S. G. Lemay and C. Dekker, Nano Lett. 8 (2008) 591.

Chemically Induced Conductance Switching in Carbon Nanotube Circuits, J. Männik, B. R. Goldsmith, A. A. Kane and P. G. Collins, Phys. Rev. Lett. 97 (2006) 016601. The article has also been described in Physics News Update (AIP).

Crossover from Kramers to Phase-­--Diffusion Switching in Moderately Damped Josephson Junctions, J. Männik, S. Li, W. Qiu, W. Chen, V. Patel, S. Han, J. E. Lukens, Phys. Rev. B71 (2005) 220509.