Publications by authors named "Gajanan M Pawar"

4 Publications

  • Page 1 of 1

Dynamic Loading and Unloading of Proteins in Polymeric Stomatocytes: Formation of an Enzyme-Loaded Supramolecular Nanomotor.

ACS Nano 2016 Feb 28;10(2):2652-60. Epub 2016 Jan 28.

Institute for Molecules and Materials, Radboud University , Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.

Self-powered artificial nanomotors are currently attracting increased interest as mimics of biological motors but also as potential components of nanomachinery, robotics, and sensing devices. We have recently described the controlled shape transformation of polymersomes into bowl-shaped stomatocytes and the assembly of platinum-driven nanomotors. However, the platinum encapsulation inside the structures was low; only 50% of the structures contained the catalyst and required both high fuel concentrations for the propelling of the nanomotors and harsh conditions for the shape transformation. Application of the nanomotors in a biological setting requires the nanomotors to be efficiently propelled by a naturally available energy source and at biological relevant concentrations. Here we report a strategy for enzyme entrapment and nanomotor assembly via controlled and reversible folding of polymersomes into stomatocytes under mild conditions, allowing the encapsulation of the proteins inside the stomach with almost 100% efficiency and retention of activity. The resulting enzyme-driven nanomotors are capable of propelling these structures at low fuel concentrations (hydrogen peroxide or glucose) via a one-enzyme or two-enzyme system. The confinement of the enzymes inside the stomach does not hinder their activity and in fact facilitates the transfer of the substrates, while protecting them from the deactivating influences of the media. This is particularly important for future applications of nanomotors in biological settings especially for systems where fast autonomous movement occurs at physiological concentrations of fuel.
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http://dx.doi.org/10.1021/acsnano.5b07689DOI Listing
February 2016

Injectable hydrogels from segmented PEG-bisurea copolymers.

Biomacromolecules 2012 Dec 28;13(12):3966-76. Epub 2012 Nov 28.

Laboratory for Macromolecular and Organic Chemistry, Department of Mechanical Engineering, Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.

We describe the preparation of an injectable, biocompatible, and elastic segmented copolymer hydrogel for biomedical applications, with segmented hydrophobic bisurea hard segments and hydrophilic PEG segments. The segmented copolymers were obtained by the step growth polymerization of amino-terminated PEG and aliphatic diisocyanate. Due to their capacity for multiple hydrogen bonding within the hydrophobic segments, these copolymers can form highly stable gels in water at low concentrations. Moreover, the gels show shear thinning by a factor of 40 at large strain, which allows injection through narrow gauge needles. Hydrogel moduli are highly tunable via the physical cross-link density and the length of the hydrophilic segments. In particular, the mechanical properties can be optimized to match the properties of biological host tissues such as muscle tissue and the extracellular matrix.
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http://dx.doi.org/10.1021/bm301242vDOI Listing
December 2012

Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions.

Beilstein J Org Chem 2010 Mar 23;6:28. Epub 2010 Mar 23.

Lehrstuhl für Makromolekulare Stoffe und Faserchemie, Institut für Polymerchemie, Universität Stuttgart, Pfaffenwaldring 55, D-70550 Stuttgart, Germany.

Norborn-5-ene-(N,N-dipyrid-2-yl)carbamide (M1) was copolymerized with exo,exo-[2-(3-ethoxycarbonyl-7-oxabicyclo[2.2.1]hept-5-en-2-carbonyloxy)ethyl]trimethylammonium iodide (M2) using the Schrock catalyst Mo(N-2,6-Me₂-C₆H₃)(CHCMe₂Ph)(OCMe(CF₃)₂)₂[Mo] to yield poly(M1-b-M2). In water, poly(M1-b-M2) forms micelles with a critical micelle-forming concentration (cmc) of 2.8 x 10⁻⁶ mol L⁻¹; Reaction of poly(M1-b-M2) with [Rh(COD)Cl]₂ (COD = cycloocta-1,5-diene) yields the Rh(I)-loaded block copolymer poly(M1-b-M2)-Rh containing 18 mg of Rh(I)/g of block copolymer with a cmc of 2.2 x 10⁻⁶ mol L⁻¹. The Rh-loaded polymer was used for the hydroformylation of 1-octene under micellar conditions. The data obtained were compared to those obtained with a monomeric analogue, i.e. CH₃CON(Py)₂RhCl(COD) (C1, Py = 2-pyridyl). Using the polymer-supported catalyst under micellar conditions, a significant increase in selectivity, i.e. an increase in the n:iso ratio was accomplished, which could be further enhanced by the addition of excess ligand, e.g., triphenylphosphite. Special features of the micellar catalytic set up are discussed.
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http://dx.doi.org/10.3762/bjoc.6.28DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2874313PMC
March 2010

Ring-opening metathesis polymerization-derived, polymer-bound Cu-catalysts for click-chemistry and hydrosilylation reactions under micellar conditions.

Dalton Trans 2009 Nov 31(41):9043-51. Epub 2009 Jul 31.

Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstrasse 15, D-04318 Leipzig, Germany.

Ring-opening metathesis polymerization has been used for the synthesis of the amphiphilic block-copolymer poly(M1-co-M3)-b-poly(M2) from the hydrophilic monomer 5-{2-[2-(2-methoxy-ethoxy)-ethoxy]-ethoxymethyl}-7-oxabicyclo[2.2.1]hept-2-ene (M2), and the hydrophobic monomers endo,exo-5-decyloxymethyl-bicyclo[2.2.1]hept-2-ene (M1) and 1,3-di(1-mesityl)-4-{[(bicyclo[2.2.1]hept-5-en-2-ylcarbonyl)oxy]methyl}-4,5-dihydro-1H-imidazol-3-ium carboxylate (M3). Poly(M1-co-M3)-b-poly(M2) was loaded with Cu and the resulting Cu(I)-loaded polymer poly(M1-co-M3)-b-poly(M2)-Cu was used for a series of Cu-catalyzed reactions under micellar conditions, i.e. for the [3 + 2] cycloaddition of azides to alkynes and for carbonyl hydrosilylation reactions. Under such micellar conditions, the polymer-bound Cu-catalyst was found to be an efficient catalyst for all reactions investigated. Turn-over numbers (TONs) in cycloaddition reactions were in the range of 200-375, those in hydrosilylation reactions approximately 2000 allowing for Cu-loadings of 0.05 mol% with respect to substrate.
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http://dx.doi.org/10.1039/b909180gDOI Listing
November 2009
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