Fuzzy Nanoassemblies: Toward Layered Polymeric Multicomposites

Decher, Gero

doi:10.1126/science.277.5330.1232

Cited by 9,720 publications

(8,555 citation statements)

References 88 publications

Supporting

Mentioning

8,349

Contrasting

Unclassified

117

Order By: Relevance

“…Finally, another synthesis route is layer-by-layer (LBL) self-assembly, based on repeated submersion of a substrate or colloidal template in solutions of oppositely charged polyelectrolytes. 28 Stepwise adsorption of ions allows cores of nanoparticles or shells around existing particles to form. Although the large size of the particles may remain a limitation, Caruso et al have developed protocols for dense and hollow SPIO sub-micron particles with interesting properties.…”

Section: Additional Methodsmentioning

confidence: 99%

Superparamagnetic Iron Oxide Nanoparticle Probes for Molecular Imaging

et al. 2006

View full text Add to dashboard Cite

Abstract-The field of molecular imaging has recently seen rapid advances in the development of novel contrast agents and the implementation of insightful approaches to monitor biological processes non-invasively. In particular, superparamagnetic iron oxide nanoparticles (SPIO) have demonstrated their utility as an important tool for enhancing magnetic resonance contrast, allowing researchers to monitor not only anatomical changes, but physiological and molecular changes as well. Applications have ranged from detecting inflammatory diseases via the accumulation of non-targeted SPIO in infiltrating macrophages to the specific identification of cell surface markers expressed on tumors. In this article, we attempt to illustrate the broad utility of SPIO in molecular imaging, including some of the recent developments, such as the transformation of SPIO into an activatable probe termed the magnetic relaxation switch.

show abstract

Section: Additional Methodsmentioning

confidence: 99%

Superparamagnetic Iron Oxide Nanoparticle Probes for Molecular Imaging

et al. 2006

View full text Add to dashboard Cite

show abstract

“…Poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}copolymer, (PBS-PFP, M n 6500, Figure 1) was synthesized by condensation of 2,7-dibromo-9,9-bis(4-sulfonylbutoxyphenyl)fluorene and 1,4-phenylenediboronic acid using Pd(PPh 3 ) 4 as a catalyst. 22,23 Gemini surfactants R,ω- 2 were prepared according to the method described by Menger et al 29 Two sets of surfactants were used for the photophysical studies. The first group has dodecyl tail chains and spacers with 2, 3, 5, 6, and 12 carbon atom alkyl chains and the second one with 2 carbon atom spacer chains and tail chains with 12, 16, and 18 carbon atoms.…”

Section: Methodsmentioning

confidence: 99%

“…The cationic gemini surfactants used in this work R,ω- 2 are referred to as m-s-m (Figure 1), where m and s are the number of carbons of the tails and spacer alkyl chains, respectively. The spacer length has a pronounced effect on the shape of any aggregate formed.…”

Section: Introductionmentioning

confidence: 99%

Interplay of Electrostatic and Hydrophobic Effects with Binding of Cationic Gemini Surfactants and a Conjugated Polyanion: Experimental and Molecular Modeling Studies

et al. 2007

View full text Add to dashboard Cite

Understanding factors responsible for the fluorescence behavior of conjugated polyelectrolytes and modulation of their behavior are important for their application as functional materials. The interaction between the anionic poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}copolymer (PBS-PFP) and cationic gemini surfactants R,ω-(C m H 2m+1 N + (CH 3 ) 2 ) 2 (CH 2 ) s (Br -) 2 (m-s-m; m ) 12, s ) 2, 3, 5, 6, 10, and 12) has been studied experimentally in aqueous solution. These surfactants are chosen to see whether molecular recognition and self-assembly occurs between the oppositely charged conjugated polyelectrolyte and gemini surfactant when the spacer length on the surfactant is similar to the intercharge separation on the polymer. Without surfactants, PBS-PFP exists as aggregates. These are broken up upon addition of gemini surfactants. However, as anticipated, the behavior strongly depends upon spacer length (s). Fluorescence measurements show three surfactant concentration regimes: At low concentrations (<2 × 10 -6 M) quenching occurs and is most marked with the small spacer 12-2-12; at intermediate concentrations (∼2 × 10 -6 -10 -3 M), fluorescence intensity is constant, with a 12-carbon spacer 12-12-12 showing the strongest fluorescence; above the critical micelle concentration (CMC; ∼10 -3 M) increases in emission intensity are seen in all cases and are largest with the intermediate spacers 12-5-12 and 12-6-12, where the spacer length most closely matches the distance between monomer units on the polymer. With longer spacer length surfactants, surface tension measurements for concentrations below the CMC reveal the presence of polymer-surfactant aggregates at the air-water interface, possibly reflecting increased hydrophobicity. Above the CMC, small-angle neutron scattering experiments for the 12-6-12 system show the presence of spherical aggregates, both for the pure surfactant and for polyelectrolyte/gemini mixtures. Molecular dynamics simulations help rationalize these observations and show that there is a very fine balance between electrostatic and hydrophobic interactions. With the shortest spacer 12-2-12, Coulombic interactions are dominant, while for the longest spacer 12-12-12 the driving force involves hydrophobic interactions. Qualitatively, with the intermediate 12-5-12 and 12-6-12 systems, the optimum balance is observed between Coulombic and hydrophobic interactions, explaining their strong fluorescence enhancement.

show abstract

“…A particularly successful method for the functionalization of surfaces and the preparation of nanoscale hybrid films is the layer-by-layer (LbL) assembly technique developed by Decher and co-workers in the 1990s [5,6]. The versatility of this approach arises from an unprecedented choice of components that can be assembled on almost any solvent-accessible interface.…”

Section: Introductionmentioning

confidence: 99%

Layer-by-Layer Assembled Films Composed of “Charge Matched” and “Length Matched” Polysaccharides: Self-Patterning and Unexpected Effects of the Degree of Polymerization

et al. 2012

Self Cite

View full text Add to dashboard Cite

The functionalization of chitosan with carboxymethyl groups allows zwitterionic or anionic chitosan derivatives to be obtained as a function of the degree of substitution. Here, we show that polyelectrolyte multilayers of chitosan and carboxymethylchitosan can be assembled by “dipping” or “spraying” to form strongly hydrated films in which both the polyanion and polycation possess the same polymer backbone (“matched chemistries”). Such films grow rapidly to fairly large thickness in very few assembly steps, especially in the case of “matched” charge densities, and atomic force microscopy reveals the formation of surface patterns that are dependent on the deposition conditions and on the number of layers. Interestingly, the influence of the molar masses of the polyelectrolyte pairs on the complex formation is somewhat counterintuitive, the stronger complexation occurring between polyanions and polycations of different (“non-matching”) lengths.

show abstract

Fuzzy Nanoassemblies: Toward Layered Polymeric Multicomposites

Cited by 9,720 publications

References 88 publications

Superparamagnetic Iron Oxide Nanoparticle Probes for Molecular Imaging

Superparamagnetic Iron Oxide Nanoparticle Probes for Molecular Imaging

Interplay of Electrostatic and Hydrophobic Effects with Binding of Cationic Gemini Surfactants and a Conjugated Polyanion: Experimental and Molecular Modeling Studies

Layer-by-Layer Assembled Films Composed of “Charge Matched” and “Length Matched” Polysaccharides: Self-Patterning and Unexpected Effects of the Degree of Polymerization

Contact Info

Product

Resources

About