Bartosz A Grzybowski

Northwestern University, Evanston, Illinois, United States

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Publications (251)2345.94 Total impact

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    ABSTRACT: A thermodynamically guided calculation of free energies of substrate and product molecules allows for the estimation of the yields of organic reactions. The non-ideality of the system and the solvent effects are taken into account through the activity coefficients calculated at the molecular level by perturbed-chain statistical associating fluid theory (PC-SAFT). The model is iteratively trained using a diverse set of reactions with yields that have been reported previously. This trained model can then estimate a priori the yields of reactions not included in the training set with an accuracy of ca. ±15 %. This ability has the potential to translate into significant economic savings through the selection and then execution of only those reactions that can proceed in good yields. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Angewandte Chemie International Edition 07/2015; DOI:10.1002/anie.201503890 · 11.26 Impact Factor
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    ABSTRACT: Metal organic frameworks (MOFs) are typically poor electrical conductors, which limits their uses in sensors, fuel cells, batteries and other applications that require electrically conductive, high surface area materials. Although metal nanoclusters (NCs) are often added to MOFs, the electrical properties of these hybrid materials have not yet been ex-plored. Here, we show that adding NCs to a MOF not only imparts moderate electrical conductivity to an otherwise insulating material but also renders it photoconductive, with conductivity increasing by up to four orders of magnitude upon light irradiation. Because charge transport occurs via tunneling between spatially separated NCs that occupy a small percent of the MOF's volume, the pores remain largely open and accessible. While these phenomena are more pronounced in single-MOF crystals (here, Rb-CD-MOFs), they are also observed in films of smaller MOF crystallites (MIL-53). Additionally, we show that in the photoconductive MOFs, the effective diffusion coefficients of electrons can match the typical values of small molecules diffusing through MOFs - this property can open new vistas for the devel-opment of MOF electrodes and, in a wider context, of electroactive and light-harvesting MOFs.
    Journal of the American Chemical Society 05/2015; 137(25). DOI:10.1021/jacs.5b03263 · 11.44 Impact Factor
  • Thomas M. Hermans · Peter S. Stewart · Bartosz A. Grzybowski
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    ABSTRACT: Chemical oscillations are studied using a continuous-flow microfluidic system transforming the time domain of chemical oscillators into a spatial domain. This system allows one (i) to monitor the dynamics of chemical oscillators with the accuracy of vigorously stirred batch reactors but with the ease and speed of CSTRs and (ii) to rapidly screen the phase space of chemical oscillators in just one experiment versus a traditional series of batch measurements.Keywords: nonlinear chemical dynamics; chemical oscillator; complexity; microfluidics; reaction−diffusion
    Journal of Physical Chemistry Letters 02/2015; 6(5):150209153233001. DOI:10.1021/jz502711c · 7.46 Impact Factor
  • H Tarik Baytekin · Bilge Baytekin · Sabil Huda · Zelal Yavuz · Bartosz A Grzybowski
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    ABSTRACT: Mechanical pulling of an adhesive tape creates radicals on the tape's surface. These radicals are capable of reducing metal salts to the corresponding metal nanoparticles. In this way, the mechanically-activated tape can be decorated with various types of nanoparticles, including Au, Ag, Pd, or Cu. While re-taining their mechanical properties and remaining "sticky," the tapes can exhibit new properties deriving from the presence of metal nanoparticles (e.g., bacterio-staticity, increased electrical conductivity). They can also be patterned with nanoparticles only at selective locations of mechanical activation.
    Journal of the American Chemical Society 01/2015; 137(5). DOI:10.1021/ja507983x · 11.44 Impact Factor
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    ABSTRACT: Recent reports that macroscopic vortex flows can discriminate between chiral molecules or their assemblies sparked considerable scientific interest both for their implications to separations technologies and for their relevance to the origins of biological homochirality. However, these earlier results are inconclusive due to questions arising from instrumental artifacts and/or insufficient experimental control. After a decade of controversy, the question remains unresolved-how do vortex flows interact with different stereoisomers? Here, we implement a model experimental system to show that chiral objects in a Taylor-Couette cell experience a chirality-specific lift force. This force is directed parallel to the shear plane in contrast to previous studies in which helices, bacteria and chiral cubes experience chirality-specific forces perpendicular to the shear plane. We present a quantitative hydrodynamic model that explains how chirality-specific motions arise in non-linear shear flows through the interplay between the shear-induced rotation of the particle and its orbital translation. The scaling laws derived here suggest that rotating flows can be used to achieve chiral separation at the micro- and nanoscales.
    Nature Communications 01/2015; 6:5640. DOI:10.1038/ncomms6640 · 10.74 Impact Factor
  • Amir Vahid · Fateme Sadat Emami · Bartosz A. Grzybowski
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    ABSTRACT: This research is focused on understanding the fundamental implications of having anisotropic temperature as well as implementing nonequilibrium self-assembly (NESA) systems in practice. In terms of theory and modeling, multiscale simulations that bridge the gap between the molecular (or nano) scale of the nonequilibrium agitating particles moving anisotropically, and the larger particles that are being agitated has been performed. During the simulations, agglomeration tests by measuring the orientational ordering (to probe and quantify the structure of the growing assemblies) has been conducted. Also, energies and entropies at various stages of NESA and compare the results with those of nonequilibrium coarse-grained field theories has been calculated. Simultaneously, several system in laboratory practice has been implemented– these systems will be based on larger assembly components being surrounded by smaller magnetic particles that can be anisotropically “jiggled” by time-varying external fields. These magnetic particles are the non-Brownian particles effectively creating an anisotropic temperature field experienced by the larger particles. The ultimate objective – and, indeed, great hope – of our work, is that we will be able to engineer self-assembling structures of arbitrary shapes and properties by designing appropriate agitation “schedules”. Of course, magnetic agitation is but the first step in these directions, and we also envision other classes of systems based on acoustic or pressure waves, and also on rapidly varying external temperature gradients. This work will create a novel experimental test-bed for studying non-equilibrium self-assembly under well-defined conditions. It can also lead to practical development in designing efficient bottom-up micro- and nanomanufacturing schemes. Molecular dynamics simulation has employed to test the above hypothesis. Several simulations with various settings were performed including change of the long-range interactions between the beads, changing the density of the system, relative diameters. The anisotropy in temperature would act as an external field that can form various patterns of self-assembled (SA) structures including hexagonal and rod shaped considering hydrodynamic and friction effects. It is found that different agitation modes play crucial form in obtaining different SA patterns. These patterns are found in DNA-coated particles, colloids, polymers, and supercooled fluids.
    14 AIChE Annual Meeting; 11/2014
  • Amir Vahid · Fatemesadat Emami · Bartosz A. Grzybowski
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    ABSTRACT: Free energy and extent of the reaction (yield) are predicted by a thermodynamically guided approach based upon estimation of free energies of compounds. The non-ideality of the system and the effect of solvent are taken into account through the fugacity coefficient calculated by Perturbed-Chain Induced-Polar Statistical Associating Fluid Theory (PCIP-SAFT) molecular theory. A structure-based formulation is defined for the Gibbs free energy and the yield is obtained from the relationship between the free energy of reaction and equilibrium constant considering temperature effects. The model is trained using a database containing 10000 cited reactions. Regression of computed Gibbs free energy and yield of reaction versus experimental values resulted in a coefficient of determination (R2) of about 0.95. The absolute average deviation of the predicted yield is ~0.15 that has been validated against sets of 2000 reactions. Finally, the proposed theory is implemented to predict retrosynthetic pathways of chemical reactions with Chematica which is the most advanced network chemistry package.
    14 AIChE Annual Meeting; 11/2014
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    ABSTRACT: Protrusions/retractions arise from forces exerted by cell cytoskeleton components to the front and back of the cells. Here, we study if overall motility strategy (diffusive versus Lvy walks) can be emerged from the front/back dynamics and weather synchronization between the two affect the overall cell movement. We have shown that a series of persistent non-Markovian infinitesimal moves could result in a power law distribution of the persistence length characterizing a Lvy walk distribution. To consider the protrusions/retractions of the cell with a primitive model represented by two connected moving points. These front and back compartment of the model were allowed to move with or without synchronization considering limitation on the overall cell size. The statistics of this unidirectional excursions were then collected to characterizing probability distributions type of motion. The model showed that the synchronization strategy affects overall cell motility pattern.
    14 AIChE Annual Meeting; 11/2014
  • Amir Vahid · Fatemesadat Emami · Bartosz A. Grzybowski
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    ABSTRACT: Scarcity of water resources is becoming an increasing challenging problem in the world. This calls for new means of water utilization, including seawater. Entropy generation has been implemented in designing a new device for desalination process based on nonequilibrium thermodynamics and interfacial/electro chemistry concepts. The efficiency of the new proposed device is almost twice of the previous apparatus proposed in the literature and therefore it is classified as a new generation membrane-free machines for the desalination process required for purification of the natural seawater used as drinking water and in related chemical and biological applications.
    14 AIChE Annual Meeting; 11/2014
  • Bartosz Grzybowski · Sijbren Otto · Douglas Philp
    Chemical Communications 10/2014; 50(95). DOI:10.1039/c4cc90422b · 6.83 Impact Factor
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    ABSTRACT: The mechanism of alternating deposition of oppositely charged gold nanoparticles (AuNPs) was investigated by optical waveguide lightmode spectroscopy (OWLS). OWLS allows monitoring of the kinetics of layer-by-layer (LbL) adsorption of positively and negatively charged nanoparticles in real time without using any labels so that the dynamics of layer formation can be revealed. Positively charged NPs that are already deposited on a negatively charged glass substrate strongly facilitate the adsorption of the negatively charged particles. The morphology of the adsorbed layer was also investigated with atomic force microscopy (AFM). AFM revealed that the interaction between oppositely charged particles results in the formation of NP clusters with sizes varying between 100 and 6000 NPs. The cluster size distribution is found to be an exponentially decaying function, and we propose a simple theory to explain this finding.
    Langmuir 10/2014; DOI:10.1021/la5029405 · 4.46 Impact Factor
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    ABSTRACT: Cell motions are driven by coordinated actions of the intracellular cytoskeleton – actin, microtubules (MTs) and substrate/focal adhesions (FAs). This coordination is altered in metastatic cancer cells resulting in deregulated and increased cellular motility. Microfabrication tools, including photolithography, micromolding, microcontact printing, wet stamping and microfluidic devices have emerged as a powerful set of experimental tools with which to probe and define the differences in cytoskeleton organization/dynamics and cell motility patterns in non-metastatic and metastatic cancer cells. In this review, we discuss four categories of microfabricated systems: (i) micropatterned substrates for studying of cell motility sub-processes (for example, MT targeting of FAs or cell polarization); (ii) systems for studying cell mechanical properties, (iii) systems for probing overall cell motility patterns within challenging geometric confines relevant to metastasis (for example, linear and ratchet geometries), and (iv) microfluidic devices that incorporate co-cultures of multiple cell types and chemical gradients to mimic in vivo intravasation/extravasation steps of metastasis. Together, these systems allow for creating controlled microenvironments that not only mimic complex soft tissues, but are also compatible with live cell high-resolution imaging and quantitative analysis of single cell behavior.
    Advanced Materials Interfaces 10/2014; 1(7). DOI:10.1002/admi.201400158
  • Yong Yan · Jaakko V I Timonen · Bartosz A Grzybowski
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    ABSTRACT: A concentration cell is composed of two equivalent half-cells made of the same material but differing in the concentration of reactants. As these concentrations equilibrate, the increase in entropy is converted into a flow of electricity with the voltage output determined by the Nernst equation and proportional to the logarithm of the concentration ratios. However, as diffusion constantly strives to erase all concentration gradients, concentration cells produce only moderate voltages (typically tens of millivolts at room temperature) over relatively short times and, consequently, such devices have not been regarded as promising for energy storage. Here, we report a concentration cell that produces significantly higher voltages (∼0.5 V) for over 100 h. The key to our design is that the citric acid molecules involved in the electrode reactions are tethered onto magnetic nanoparticles, and a sharp gradient (10(7)-10(11) anode/cathode concentration ratio) is maintained at one of the electrodes by a permanent magnet external to the cell. Our cell does not result in corrosion of the electrodes, produces no harmful by-products, and can be regenerated by recoating used nanoparticles with fresh citric acid. We show that a series of such centimetre-sized cells produces enough electricity to power small electronic devices (timers and calculators) for several tens of hours. Our results illustrate how redox-active molecules that are, in themselves, non-magnetic can be effectively concentrated by magnetic fields to produce electrical energy.
    Nature Nanotechnology 09/2014; 9(11). DOI:10.1038/nnano.2014.198 · 33.27 Impact Factor
  • Bartosz A. Grzybowski
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    ABSTRACT: Metal nanoparticles functionalized with self-assembled monolayers of ligands terminated in charged groups constitute a unique class of nanoscopic polyions – or “nanoions” in short – capable of assembling into higher-order structures ranging from two-dimensional coatings on various types of surfaces (including chemically inert polymers as well as inorganic microcrystals) to three-dimensional nanoparticle crystals. These crystals can comprise either spherical or non-spherical nanoparticles, can feature unusual particle arrangements (e.g., diamond-like), and – after already being assembled – can be further “post-processed” to act as chemical sensors of unmatched sensitivity. This “post-processing” of the crystals involves functionalization with dithiols that bridge nearby particles but are cleavable in the presence of either small-molecule or enzyme analytes. When the dithiols are cut, the NP crystals disintegrate into tens of millions of brightly colored individual particles translating the presence of few analyte molecules into a macroscopic color change readily detectable to the naked eye. Demonstrations such as this one illustrate what we believe should be the future of nanoscale assembly – namely, synthesis of structures in which nanoscopic components enable new and useful functions.
    CrystEngComm 09/2014; 16(40). DOI:10.1039/C4CE00689E · 3.86 Impact Factor
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    ABSTRACT: A three-component system comprising surfactant molecules and molecularly crosslinked metal centers assembles into nanoring structures. The thickness of the nanorings is determined by the dimensions of the surfactant bilayer while the dimensions of the ring opening depend on and can be regulated by the concentrations of the participating species. Once formed, these organic-inorganic hybrids can be transformed, by air plasma treatment, into all-metal nanorings exhibiting strong adsorption in the near IR.
    Langmuir 08/2014; 30(33). DOI:10.1021/la5020913 · 4.46 Impact Factor
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    ABSTRACT: Methods of computational linguistics are used to demonstrate that a natural language such as English and organic chemistry have the same structure in terms of the frequency of, respectively, text fragments and molecular fragments. This quantitative correspondence suggests that it is possible to extend the methods of computational corpus linguistics to the analysis of organic molecules. It is shown that within organic molecules bonds that have highest information content are the ones that 1) define repeat/symmetry subunits and 2) in asymmetric molecules, define the loci of potential retrosynthetic disconnections. Linguistics-based analysis appears well-suited to the analysis of complex structural and reactivity patterns within organic molecules.
    Angewandte Chemie 07/2014; 126(31). DOI:10.1002/ange.201403708
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    ABSTRACT: Methods of computational linguistics are used to demonstrate that a natural language such as English and organic chemistry have the same structure in terms of the frequency of, respectively, text fragments and molecular fragments. This quantitative correspondence suggests that it is possible to extend the methods of computational corpus linguistics to the analysis of organic molecules. It is shown that within organic molecules bonds that have highest information content are the ones that 1) define repeat/symmetry subunits and 2) in asymmetric molecules, define the loci of potential retrosynthetic disconnections. Linguistics-based analysis appears well-suited to the analysis of complex structural and reactivity patterns within organic molecules.
    Angewandte Chemie International Edition 07/2014; 53(31). DOI:10.1002/anie.201403708 · 11.26 Impact Factor
  • Bilge Baytekin · H. Tarik Baytekin · Bartosz A. Grzybowski
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    ABSTRACT: Mechanical treatment of polymers produces surface cations and anions which, as demonstrated here for the first time, can drive chemical reactions. In particular, it is shown that such a mechanical treatment transforms nonconductive polyaniline into its conductive form. These results provide a mechanical means of patterning conductive polymers and also coating small polymer objects with conductive polyaniline films preventing accumulation of static electricity. Rubbing makes conductive: Contact-charged and mechanically deformed polymers can transform nonconductive polyaniline (PANI) into its conductive form with the help of mechano-ions formed at the polymer's surface. This phenomenon provides a convenient way for printing conductive patterns into PANI and also for rendering small polymeric objects antistatic.
    Angewandte Chemie International Edition 07/2014; 53(27). DOI:10.1002/anie.201311313 · 11.26 Impact Factor
  • Bilge Baytekin · H. Tarik Baytekin · Bartosz A. Grzybowski
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    ABSTRACT: Mechanical treatment of polymers produces surface cations and anions which, as demonstrated here for the first time, can drive chemical reactions. In particular, it is shown that such a mechanical treatment transforms nonconductive polyaniline into its conductive form. These results provide a mechanical means of patterning conductive polymers and also coating small polymer objects with conductive polyaniline films preventing accumulation of static electricity.
    Angewandte Chemie 07/2014; 126(27). DOI:10.1002/ange.201311313
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    ABSTRACT: In materials design, cracks are often avoided rather than sought. Here, several design principles are implemented that allow cracks to be formed with high reproducibility and control. We show how strains applied to flexible substrates produce nanoscopic cracks mediating size-, shape- and location-selective deposition of nanomaterials.
    Advanced Materials 06/2014; 26(22). DOI:10.1002/adma.201306335 · 17.49 Impact Factor

Publication Stats

9k Citations
2,345.94 Total Impact Points

Institutions

  • 2004–2015
    • Northwestern University
      • • Department of Chemical and Biological Engineering
      • • Department of Chemistry
      Evanston, Illinois, United States
  • 2014
    • Hungarian Academy of Sciences
      Budapeŝto, Budapest, Hungary
  • 2010
    • Northwestern Polytechnical University
      • School of Materials Science and Engineering
      Xi’an, Liaoning, China
    • Northwest University
      Evanston, Illinois, United States
  • 2005
    • New England Complex Systems Institute
      Evanston, Illinois, United States
  • 1998–2003
    • Harvard University
      • Department of Chemistry and Chemical Biology
      Cambridge, Massachusetts, United States