Dr. Leonid Ionov
Elisabeth Kaul
Polymer brushes are the dense surface-grafted polymer layers. We synthesize and investigate homopolymer, mixed polymer, gradient and patterned polymer brushes as well as apply them for design of smart sensors, patterning of proteins, microfludic devices.
Synthesis
We use two approaches for synthesis of polymer brushes: "grafting to" and "grafting from". In "grafting to" approach functionalized polymer chains are grafted on activated substrate. "Grafting from" is the surface initiated polymerisation.
Synthesis of polymer brushes using "grafting to" and "grafting from" approaches
Application
1. Sensors
We design environmental sensors based on fluorescence interference contras (FLIC) of semiconductor nanocrystals (qauntum dots) adsorbed on polymer brush which is grafted on a reflecting silicon surface. FLIC arises from the interference between light that is directly emitted (or absorbed) by a nanoparticle and the light that is reflected by the mirror surface. Consequently, the intensity of the detected fluorescence light becomes a periodic function of the nanoparticle distance from the surface. Fluorescent nanoparticles located in close proximity to the mirror surface will appear dark, while particles about a quarter-wavelength away will appear with maximum brightness. Inserting a polymer brush layer, whose thickness depends on the environmental conditions (temperature, pH, sovent), provides a simple and cheap strategy for the design of a sensor.
Schematic of the polymer brush - quantum dot sensor. Quantum dots are adsorbed on a stimuli-responsive polymer brush layer that was previously grafted onto a reflecting substrate. The quatum dot–surface distance depends on the conformation of the polymer chains and changes in different solvents. The change in height is then reported by a variation in the detected fluorescence intensity.more
2. Active control of liquid flow
We use stimuli-responsive polymer brushes for control of liquid flow on microscale. In particular we design gradient and patterned brushes for lateral separation of liquids as well as for gating of liquid flow.
Separation of water-toluene emulsion on grafted mixed gradient polystyrene – poly-(2- vinyl pyridine) brush (I) mounted on the PDMS channel (II). Toluene and water are colored by rhodamine and fluorol green-gold fluorescent dyes, respectively. more
3. Active control of interaction with proteins
In collaboration with the groups of Dr. Stefan Diez (Max-Planck Institute of Molecular Cell Biology and Genetic) and Prof. Dirk Kuckling (University Paderborn) we design and test novel strategies to influence the in vitro operation of biomolecular transport systems using stimuli-responsive polymer brushes. In particular, we desing thermo- and photoresponsive polymer brushes to spatio-temporally control the gliding motion of microtubule filaments on surfaces coated with kinesin motor proteins.
Gliding motility of microtubules on a polyethyleneglycol (PEG)-gradient brush surface with immobilized kinesin. While the grafting density of PEG increases from left to right, the kinesin gradient is formed in the opposite direction. Because at least two kinesins per microtubule are required for continuous gliding, the average microtubule length varies as function of the lateral position and the PEG grafting density. more
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Repeated changes in temperature resulted in the reversible switching of poly-(N isopropylacrylamide) chains between the extended conformation (where microtubules are repelled from the surface and cannot bind to the kinesin heads) and the collapsed conformation (where microtubules can glide unhindered on the kinesin molecules). more
References
Ionov, L.; Minko, S.
Mixed Polymer Brushes with Locking Switching more
ACS Applied Materials & Interfaces 4(1) (2012) 483–489.Ionov, L.
Actively-moving materials based on stimuli-responsive polymers more
Journal of Materials Chemistry 20 (2010) 3382-3390Ionov, L.; Bocharova, V.; Diez, S.
Biotemplated synthesis of stimuli-responsive nanopatterned polymer brushes on microtubules more
Soft Matter 5 (2009) 67-71Hinrichs, K.; Aulich, D.; Ionov, L.; Esser, N.; Eichhorn, K.-J.; Motornov, M.; Stamm, M.; Minko, S.
Chemical and structural changes in a pH-responsive mixed polyelectrolyte brushes studied by infrared ellipsometry more
Langmuir 25 (2009) 10987-10991Ionov, L.; Houbenov, N.; Sidorenko, A.; Stamm, M.; Minko, S.
Stimuli-responsive command polymer surface for generation of protein gradients more
Biointerphases : An Open Access Journal for the Biomaterials Interfaces Community 4 (2009) FA45-FA49Berger, S.; Synytska, A.; Ionov, L.; Eichhorn, K.-J.; Stamm, M.
Stimuli-responsive bicomponent polymer janus particles by "grafting from"/"grafting to" approaches more
Macromolecules 41 (2008) 9669-9676Ionov, L.; Synytska, A.; Diez, S.
Temperature-induced size-control of bioactive surface patterns more
Advanced Functional Materials 18 (2008) 1501-1508Roodenko, K.; Mikhailova, Y.; Ionov, L.; Gensch, M.; Stamm, M.; Minko, S.; Schade, U.; Eichhorn, K.-J.; Esser, N.; Hinrichs, K.
Ultrathin responsive polyelectrolyte brushes studied by infrared synchrotron mapping ellipsometry more
Applied Physics Letters 92 (2008) 103102 (3 pp.)Mikhailova, Y.; Ionov, L.; Rappich, J.; Gensch, M.; Esser, N.; Minko, S.; Eichhorn, K.-J.; Stamm, M.; Hinrichs, K.
In-situ infrared ellipsometric study of stimuli-responsive mixed polyelectrolyte brushes more
Analytical Chemistry 79 (2007) 7676-7682Uhlmann, P.; Houbenov, N.; Ionov, L.; Motornov, M.; Minko, S.; Stamm, M.
Oberflächen passen sich an - bürstenartige Polymermoleküle an Oberflächen mit schaltbaren Eigenschaften more
Wissenschaftliche Zeitschrift der Technischen Universität Dresden 56 (2007) 47-51Synytska, A.; Stamm, M.; Diez, S.; Ionov, L.
Simple and fast method for the fabrication of switchable biocomponent micropatterned polymer surfaces more
Langmuir 23 (2007) 5205-5209Ionov, L.; Sapra, S.; Synytska, A.; Rogach, A. L.; Stamm, M.; Diez, S.
Fast and Spatially Resolved Environmental Probing Using Stimuli-Responsive Polymer Layers and Fluorescent Nanocrystals more
Advanced Materials 18 (2006) 1453-1457Ionov, L.; Houbenov, N.; Sidorenko, A.; Stamm, M.; Minko, S.
Smart Microfluidic Channels more
Advanced Functional Materials 16 (2006) 1153-1160Ionov, L.; Stamm, M.; Diez, S.
Reversible Switching of Microtubule Motility Using Thermoresponsive Polymer Surfaces more
Nano letters 6 (2006) 1982-1987Ionov, L.; Sidorenko, A.; Eichhorn, K.-J.; Stamm, M.; Minko, S.; Hinrichs, K.
Stimuli Responsive Mixed Grafted Polymer Films with Gradually Changing Properties: Direct Determination of Chemical Composition more
Langmuir 21 (2005) 8711-8716Minko, S.; Ionov, L.; Sydorenko, A.; Houbenov, N.; Stamm, M.; Zdyrko, B.; Klep, V.; Luzinov, I.
Gradient Stimuli-Responsive Polymer Grafted Layers more
in: Stimuli-responsive Polymeric Films And Coatings, Marek W. Urban, ed. (Oxford University Press 2005) Chapter 5, 68-83Ionov, L.; Stamm, M.; Diez, S.
Size sorting of protein assemblies using polymeric gradient surfaces more
Nano letters 5 (2005) 1910-1914Ionov, L.; Houbenov, N.; Sidorenko, A.; Stamm, M.; Luzinov, I.; Minko, S.
Inverse and Reversible Switching Gradient Surfaces from Mixed Polyelectrolyte Brushes more
Langmuir 20 (2004) 9916-9919Ionov, L.; Sidorenko, A.; Stamm, M.
Gradient Mixed Brushes: "Grafting To" approach more
Macromolecules 37 (2004) 7421-7423Ionov, L.; Zdyrko, B.; Sidorenko, A.; Minko, S.; Klep, V.; Luzinov, I.; Stamm, M.
Gradient Polymer Layers by "Grafting To" Approach more
Macromolecular Rapid Communications 25 (2004) 360-365Ionov, L.; Minko, S.; Stamm, M.; Gohy, J.F.; Jérome, R.; Scholl, A.
Reversible Chemical Patterning on Stimuli-Responsive Polymer Film - Environment Responsive Lithography more
Journal of the American Chemical Society 125 (2003) 8302-8306
Co-operation
Prof. Andrey Rogach
University of Hong Kong
Prof. Alexander Eychmüller
TU Dresden
Prof. Sergiy Minko
Clarkson University
Prof. Igor Luzinov
Clemson University
Dr. Karsten Hinrichs
ISAS Berlin
Dr. Klaus-Jochen Eichhorn
IPF
Dr. Stefan Diez
Max-Planck Institute of Molecular Cell Biology and Genetic
Prof. Dirk Kuckling
University Paderborn
