Conformations of high-generation dendritic polyelectrolytes

We perform monomer-resolved computer simulations of high-generation dendritic molecules, varying the amount of charge and the spacer length between subsequent generations. Charged entities (monomers and counterions) are simulated with the explicit Coulomb interaction, employing the Ewald summation technique. We discover considerable stretching of the molecules with increasing generation number and spacer length, whereas the effects of charging are less pronounced on the overall size of the molecule than those of the former two parameters. For large generations and spacer lengths, charging of the molecules leads to both the opening of large voids within the dendrimer and to charge distributions that are nearly uniform along the molecule's extent. These findings suggest both the possible usage of charge dendrimers as efficient encapsulating agents and their character as realizations of model charged colloids with a uniform charge distribution in their interior.

[1]  M. Muthukumar,et al.  Configurational characteristics and scaling behavior of starburst molecules: a computational study , 1990 .

[2]  Kurt Kremer,et al.  Structure of many arm star polymers: a molecular dynamics simulation , 1987 .

[3]  Antony D'Emanuele,et al.  Dendrimer-drug interactions. , 2005, Advanced drug delivery reviews.

[4]  V. Urban,et al.  Dynamics of star-burst dendrimers in solution in relation to their structural properties , 2002 .

[5]  Yu-qiang Ma,et al.  Molecular dynamics simulations of a charged dendrimer in multivalent salt solution. , 2009, The journal of physical chemistry. B.

[6]  H. Löwen,et al.  Star Polymers Viewed as Ultrasoft Colloidal Particles , 1998 .

[7]  Gregory S Smith,et al.  Structural investigation of PAMAM dendrimers in aqueous solutions using small-angle neutron scattering: effect of generation. , 2008, The journal of physical chemistry. B.

[8]  C. N. Likos,et al.  Tunable effective interactions between dendritic macromolecules. , 2004, The Journal of chemical physics.

[9]  H. C. Andersen,et al.  Role of Repulsive Forces in Determining the Equilibrium Structure of Simple Liquids , 1971 .

[10]  Peter Lindner,et al.  Analysis of the structure of dendrimers in solution by small-angle neutron scattering including contrast variation , 1999 .

[11]  A. R. Denton.  Counterion penetration and effective electrostatic interactions in solutions of polyelectrolyte stars and microgels. , 2003, Physical review. E, Statistical, nonlinear, and soft matter physics.

[12]  J. Dennig,et al.  Gene transfer into eukaryotic cells using activated polyamidoamine dendrimers. , 2002, Journal of biotechnology.

[13]  Umesh Gupta,et al.  Dendrimers: novel polymeric nanoarchitectures for solubility enhancement. , 2006, Biomacromolecules.

[14]  Christos N. Likos,et al.  EFFECTIVE INTERACTIONS IN SOFT CONDENSED MATTER PHYSICS , 2001 .

[15]  Peter Lindner,et al.  Determination of the structure factor of polymeric systems in solution by small‐angle scattering: A SANS‐study of a dendrimer of fourth generation , 2002 .

[16]  Berend Smit,et al.  Understanding Molecular Simulation , 2001 .

[17]  G. Grest,et al.  Molecular Dynamics Study of Dendrimer Molecules in Solvents of Varying Quality , 1996 .

[18]  Arash Nikoubashman,et al.  Flow-induced polymer translocation through narrow and patterned channels. , 2010, The Journal of chemical physics.

[19]  J. Sommer,et al.  Simulations of Terminally Charged Dendrimers with Flexible Spacer Chains and Explicit Counterions , 2010 .

[20]  G. Giupponi,et al.  Are Polyelectrolyte Dendrimers Stimuli Responsive , 2007 .

[21]  Richard M Crooks,et al.  Synthesis, characterization, and applications of dendrimer-encapsulated nanoparticles. , 2005, The journal of physical chemistry. B.

[22]  L. Klushin,et al.  Monte Carlo studies of dendrimer macromolecules , 1993 .

[23]  S. Edwards,et al.  The Theory of Polymer Dynamics , 1986 .

[24]  Kremer,et al.  Molecular dynamics simulation for polymers in the presence of a heat bath. , 1986, Physical review. A, General physics.

[25]  W. Goddard,et al.  Solvent quality changes the structure of G8 PAMAM dendrimer, a disagreement with some experimental interpretations. , 2006, The journal of physical chemistry. B.

[26]  P. Gennes,et al.  Statistics of « starburst » polymers , 1983 .

[27]  Michael Rubinstein,et al.  A Self-Consistent Mean Field Model of a Starburst Dendrimer: Dense Core vs Dense Shell , 1996 .

[28]  Yu-qiang Ma,et al.  Effects of valences of salt ions at various concentrations on charged dendrimers , 2010 .

[29]  C. N. Likos,et al.  Colloquium: Star-branched polyelectrolytes: The physics of their conformations and interactions , 2009 .

[30]  C. N. Likos,et al.  Conformations of Flexible Dendrimers: A Simulation Study , 2003 .

[31]  Christos N Likos,et al.  Soft matter with soft particles. , 2006, Soft matter.

[32]  C. N. Likos,et al.  Branched Polymers under Shear , 2010 .

[33]  I. Vattulainen,et al.  Molecular dynamics study of charged dendrimers in salt-free solution: effect of counterions. , 2005, The Journal of chemical physics.

[34]  A. Wynveen,et al.  The effects of pH, salt and bond stiffness on charged dendrimers , 2010, Journal of physics. Condensed matter : an Institute of Physics journal.

[35]  Anders Hult,et al.  A chemoselective approach for the accelerated synthesis of well-defined dendritic architectures. , 2007, Chemical communications.

[36]  R. Blaak,et al.  Charge-induced conformational changes of dendrimers , 2008, 0804.1465.

[37]  K. Herwig,et al.  Effect of counterion valence on the pH responsiveness of polyamidoamine dendrimer structure. , 2010, The Journal of chemical physics.

[38]  Zhengxiu Chen,et al.  Monte Carlo Simulations of Star-Burst Dendrimers , 1996 .

[39]  William A. Goddard,et al.  Starburst Dendrimers: Molecular‐Level Control of Size, Shape, Surface Chemistry, Topology, and Flexibility from Atoms to Macroscopic Matter , 1990 .

[40]  W. Goddard,et al.  PAMAM dendrimers undergo pH responsive conformational changes without swelling. , 2009, Journal of the American Chemical Society.

[41]  P. Flory.  Principles of polymer chemistry , 1953 .

[42]  P. Butler,et al.  Assess the Intramolecular Cavity of a PAMAM Dendrimer in Aqueous Solution by Small-Angle Neutron Scattering , 2008 .

[43]  A. Wynveen,et al.  Computer simulations of polyelectrolyte stars and brushes , 2008 .

[44]  K. Herwig,et al.  Intramolecular structural change of PAMAM dendrimers in aqueous solutions revealed by small-angle neutron scattering. , 2010, The journal of physical chemistry. B.

[45]  G. Pickett,et al.  Hollow-core dendrimers revisited. , 2003, Physical review letters.

[46]  R. Ivkov,et al.  Size Invariance of Polyelectrolyte Dendrimers , 2000 .

[47]  M. Ozkan,et al.  Nano-oncology: drug delivery, imaging, and sensing , 2006, Analytical and bioanalytical chemistry.

[48]  Peter Lindner,et al.  The structure of dendritic molecules in solution as investigated by small‐angle neutron scattering , 2000 .

[49]  P. Butler,et al.  Small Angle Neutron Scattering Studies of the Counterion Effects on the Molecular Conformation and Structure of Charged G4 PAMAM Dendrimers in Aqueous Solutions , 2007 .

[50]  M. Ballauff,et al.  Dendrimers in solution: insight from theory and simulation. , 2004, Angewandte Chemie.

[51]  F. Szoka,et al.  Polyamidoamine cascade polymers mediate efficient transfection of cells in culture. , 1993, Bioconjugate chemistry.