@article{WagnerLazarSchnakenbergetal.2016,
  author    = {Wagner, Tom and Lazar, Jaroslav and Schnakenberg, Uwe and B{\"o}ker, Alexander},
  title     = {In situ Electrothemical Impedance Spectroscopy of Electrostatically Driven Selective Gold Nanoparticle Adsorption on Block Copolymer Lamellae},
  series = {Trials},
  volume    = {8},
  journal   = {Trials},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1944-8244},
  doi       = {10.1021/acsami.6b07708},
  pages     = {27282 -- 27290},
  year      = {2016},
  abstract  = {Electrostatic attraction between charged nano particles and oppositely charged nanopatterned polymeric films enables tailored structuring of functional nanoscopic surfaces. The bottom-up fabrication of organic/inorganic composites for example bears promising potential toward cheap fabrication of catalysts, optical sensors, and the manufacture of miniaturized electric circuitry. However, only little is known about the time-dependent adsorption behavior and the electronic or ionic charge transfer in the film bulk and at interfaces during nanoparticle assembly via electrostatic interactions. In situ electrochemical impedance spectroscopy (EIS) in combination with a microfluidic system for fast and reproducible liquid delivery was thus applied to monitor the selective deposition of negatively charged gold nanoparticles on top of positively charged poly(2-vinylpyridinium) (qP2VP) domains of phase separated lamellar poly(styrene)-block-poly(2-vinylpyridinium) (PS-b-qP2VP) diblock copolymer thin films. The acquired impedance data delivered information with respect to interfacial charge alteration, ionic diffusion, and the charge dependent nanoparticle adsorption kinetics, considering this yet unexplored system. We demonstrate that the selective adsorption of negatively charged gold nanoparticles (AuNPs) on positively charged qP2VP domains of lamellar PS-b-qP2VP thin films can indeed be tracked by EIS. Moreover, we show that the nanoparticle adsorption kinetics and the nanoparticle packing density are functions of the charge density in the qP2VP domains.},
  language  = {en}
}
@misc{NguyenRichertParketal.2017,
  author    = {Nguyen, Vu Hoa and Richert, S. and Park, Hyunji and B{\"o}ker, Alexander and Schnakenberg, Uwe},
  title     = {Single interdigital transducer as surface acoustic wave impedance sensor},
  series = {Biosensors},
  volume    = {27},
  journal   = {Biosensors},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {2212-0173},
  doi       = {10.1016/j.protcy.2017.04.032},
  pages     = {70 -- 71},
  year      = {2017},
  abstract  = {Surface acoustic wave (SAW) devices are well-known for gravimetric sensor applications. In biosensing applications, chemical-and biochemically evoked adsorption processes at surfaces are detected in liquid environments using delay-line or resonator sensor configurations, preferably in combination with appropriate microfluidic devices. In this paper, a novel SAW-based impedance sensor type is introduced which uses only one interdigital electrode transducer (IDT) simultaneously as SAW generator and sensor element. It is shown that the amplitude of the reflected S-11 signal directly depends on the input impedance of the SAW device. The input impedance is strongly influenced by mass adsorption which causes a characteristic and measurable impedance mismatch.},
  language  = {en}
}
@article{GarakaniLiuGlebeetal.2019,
  author    = {Garakani, Tayebeh Mirzaei and Liu, Zhanzhi and Glebe, Ulrich and Gehrmann, Julia and Lazar, Jaroslav and Mertens, Marie Anna Stephanie and M{\"o}ller, Mieke and Hamzelui, Niloofar and Zhu, Leilei and Schnakenberg, Uwe and B{\"o}ker, Alexander and Schwaneberg, Ulrich},
  title     = {In Situ Monitoring of Membrane Protein Insertion into Block Copolymer Vesicle Membranes and Their Spreading via Potential-Assisted Approach},
  series = {ACS applied materials \& interfaces},
  volume    = {11},
  journal   = {ACS applied materials \& interfaces},
  number    = {32},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1944-8244},
  doi       = {10.1021/acsami.9b09302},
  pages     = {29276 -- 29289},
  year      = {2019},
  abstract  = {Synthosomes are polymer vesicles with trans membrane proteins incorporated into block copolymer membranes. They have been used for selective transport in or out of the vesicles as well as catalysis inside the compartments. However, both the insertion process of the membrane protein, forming nanopores, and the spreading of the vesicles on planar substrates to form solid-supported biomimetic membranes have been rarely studied yet. Herein, we address these two points and, first, shed light on the real-time monitoring of protein insertion via isothermal titration calorimetry. Second, the spreading process on different solid supports, namely, SiO2, glass, and gold, via different techniques like spin- and dip-coating as well as a completely new approach of potential-assisted spreading on gold surfaces was studied. While inhomogeneous layers occur via traditional methods, our proposed potential-assisted strategy to induce adsorption of positively charged vesicles by applying negative potential on the electrode leads to remarkable vesicle spreading and their further fusion to form more homogeneous planar copolymer films on gold. The polymer vesicles in our study are formed from amphiphilic copolymers poly(2-methyl oxazoline)-block-poly(dimethylsiloxane)-block-poly(2-methyl oxazoline) (PMOXA-b-PDMS-b-PMOXA). Engineered variants of the transmembrane protein ferric hydroxamate uptake protein component A (FhuA), one of the largest beta-barrel channel proteins, are used as model nanopores. The incorporation of FhuA Delta 1-160 is shown to facilitate the vesicle spreading process further. Moreover, high accessibility of cysteine inside the channel was proven by linkage of a fluorescent dye inside the engineered variant FhuA Delta CVFtev and hence preserved functionality of the channels after spreading. The porosity and functionality of the spread synthosomes on the gold plates have been examined by studying the passive ion transport response in the presence of Li+ and ClO4- ions and electrochemical impedance spectroscopy analysis. Our approach to form solid-supported biomimetic membranes via the potential-assisted strategy could be important for the development of new (bio-) sensors and membranes.},
  language  = {en}
}