Quantitative investigations of the aggregation behaviour of hydrophobic anilino squaraine dyes through UV/vis spectroscopy and dynamic light scattering

1999 ◽  
Vol 77 (5-6) ◽  
pp. 903-912 ◽  
Author(s):  
James Wojtyk ◽  
Andrew McKerrow ◽  
Peter Kazmaier ◽  
Erwin Buncel
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Particle Diameter ◽  
Water Medium ◽  
Thermodynamic Control ◽  
Squaraine Dyes ◽  
Water Solvent ◽  
Aggregation Behaviour ◽  
Vis Spectroscopy ◽  
J Aggregates

In continuing studies of the aggregation behaviour of squaraine dyes in DMSO-water mixtures, we have examined a series of symmetrical anilino-based squaraines with increasing N-alkyl chain length (n-butyl, n-octyl, and n-dodecyl). The aggregation behaviour was assessed through UV/vis spectroscopic and Dynamic Light Scattering (DLS) studies with quantitative interpretation based on exciton theory. This class of N-alkyl squaraines forms two distinct solution aggregates, Type J and Type H, depending on the composition of the DMSO-water medium. DLS measurement of the aggregates in the Type J and Type H morphologies showed that (i) the particle diameter increased with increasing hydrophobicity; (ii) DMSO has a large effect on the aggregate size; (iii) Type J aggregates are of equal dimensions with Type H aggregates. Moreover, even though as the DMSO-water solvent composition is varied the UV/vis spectra of Type H and Type J aggregates remained unchanged, the number of molecules comprising each aggregate varies widely. It is proposed that the dynamic conversion (J →> H) results from intramolecular reorganization of individual molecules within the aggregate. Quantification of aggregation through DLS has further developed the "kinetic" versus "thermodynamic" control model of dye aggregation.Key words: squaraine, dynamic light scattering, DMSO-water mixtures, self-assembly, kinetic/thermodynamic control.

scholarly journals Detection Limits of DLS and UV-Vis Spectroscopy in Characterization of Polydisperse Nanoparticles Colloids

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Emilia Tomaszewska ◽  
Katarzyna Soliwoda ◽  
Kinga Kadziola ◽  
Beata Tkacz-Szczesna ◽  
Grzegorz Celichowski ◽  
...  
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Point Of View ◽  
Spectroscopy Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
The One

Dynamic light scattering is a method that depends on the interaction of light with particles. This method can be used for measurements of narrow particle size distributions especially in the range of 2–500 nm. Sample polydispersity can distort the results, and we could not see the real populations of particles because big particles presented in the sample can screen smaller ones. Although the theory and mathematical basics of DLS technique are already well known, little has been done to determine its limits experimentally. The size and size distribution of artificially prepared polydisperse silver nanoparticles (NPs) colloids were studied using dynamic light scattering (DLS) and ultraviolet-visible (UV-Vis) spectroscopy. Polydisperse colloids were prepared based on the mixture of chemically synthesized monodisperse colloids well characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), DLS, and UV-Vis spectroscopy. Analysis of the DLS results obtained for polydisperse colloids reveals that several percent of the volume content of bigger NPs could screen completely the presence of smaller ones. The presented results could be extremely important from nanoparticles metrology point of view and should help to understand experimental data especially for the one who works with DLS and/or UV-Vis only.

Synthesis and properties of multiheaded and multitailed surfactants based on tripentaerythritol

2015 ◽  
Vol 93 (5) ◽  
pp. 502-508 ◽  
Author(s):  
Nawal K. Paul ◽  
Tyler Mercer ◽  
Hussein Al-Mughaid ◽  
D. Gerrard Marangoni ◽  
Michael J. McAlduff ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Surface Tension ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Self Assembly ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Aggregation Behaviour ◽  
Aggregate Structures

The surface and self-assembly properties of a family of multiheaded, multitailed surfactants based on a tripentaerythritol backbone are described. Critical aggregation concentrations of these unusual surfactant systems have been determined from surface tension measurements; aggregate sizes in the presence and absence of a small amount of added electrolyte have been obtained via dynamic light scattering, and the morphologies of the aggregates were examined from electron microscopy measurements. In general, when compared to conventional ionic and two-headed surfactants (and other recently synthesized pentaerythritol derived surfactants from this group), these multiheaded surfactants exhibited some unusual trends in their aggregation behaviour and interesting aggregate structures in aqueous solution, as a function of alkyl chain length.

Assembly of DNA-functionalized gold nanoparticles studied by UV/Vis-spectroscopy and dynamic light scattering

2008 ◽  
Vol 10 (14) ◽  
pp. 1870 ◽  
Author(s):  
Katrin G. Witten ◽  
Jan C. Bretschneider ◽  
Thomas Eckert ◽  
Walter Richtering ◽  
Ulrich Simon
Keyword(s):  
Gold Nanoparticles ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Functionalized Gold Nanoparticles ◽  
Vis Spectroscopy

Dynamic light scattering and UV–vis spectroscopy of gold nanoparticles solution

2011 ◽  
Vol 65 (19-20) ◽  
pp. 2906-2909 ◽  
Author(s):  
M. Zimbone ◽  
L. Calcagno ◽  
G. Messina ◽  
P. Baeri ◽  
G. Compagnini
Keyword(s):  
Gold Nanoparticles ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Vis Spectroscopy

scholarly journals Protein-mediated gelation and nano-scale assembly of unfunctionalized hyaluronic acid and chondroitin sulfate

F1000Research ◽  
2019 ◽  
Vol 7 ◽  
pp. 1827
Author(s):  
Anthony Tabet ◽  
June Y. Park ◽  
Jarrod Shilts ◽  
Kamil Sokolowski ◽  
Vijay K. Rana ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Nervous System ◽  
Hyaluronic Acid ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Chondroitin Sulfate ◽  
Biological Tissues ◽  
Simple Method ◽  
Vis Spectroscopy

Background: Hyaluronic acid (HA) is a major component of the extracellular matrix (ECM) in the central nervous system and the only purely supramolecular glycosaminoglycan. Much focus has been given to using this high molecular weight polysaccharide for tissue engineering applications. In most studies, the backbone of HA is functionalized with moieties that can facilitate network formation through physical self-assembly, or covalent crosslinking (e.g. photo-catalyzed) at concentrations where the polysaccharide does not gel on its own. However, these crosslinks often utilize functional groups not found in biological tissues. Methods: Oscillatory rheology, dynamic light scattering, and scanning electron microscopy were used to study albumin/HA structures. Dynamic light scattering and transmission electron microscopy were used to study albumin/chondroitin sulfate (CS) structures. UV-vis spectroscopy was used to demonstrate the potential for using protein-polymer blends as an ECM-mimetic model to study transport of small molecules. Results: We examine the intermolecular interactions of two major glycosaminoglycans found in the human brain, HA and the lower molecular weight CS, with the model protein albumin. We report the properties of the resulting micro- and nano materials. Our albumin/HA systems formed gels, and albumin/CS systems formed micro- and nanoparticles. These systems are formed from unfunctionalized polysaccharides, which is an attractive and simple method of forming HA hydrogels and CS nanoparticles. We also summarize the concentrations of HA and CS found in various mammalian brains, which could potentially be useful for biomimetic scaffold development. Conclusions: Simple preparation of commercially available charged biomacromolecules results in interesting materials with structures at the micron and nanometer length-scales. Such materials may have utility in serving as cost-effective models of nervous system electrostatic interactions and as in vitro drug release and model system for ECM transport studies.

scholarly journals Superstructures of fluorescent cyclodextrin via click-reaction

2013 ◽  
Vol 9 ◽  
pp. 827-831 ◽  
Author(s):  
Arkadius Maciollek ◽  
Helmut Ritter ◽  
Rainer Beckert
Keyword(s):  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Flow Field ◽  
Click Reaction ◽  
Field Flow Fractionation ◽  
Asymmetric Flow ◽  
H Nmr ◽  
Intermolecular Complexes ◽  
Vis Spectroscopy ◽  
Polymeric Structures

Mono-(6-azido-6-deoxy)-β-cyclodextrin (CD) was covalently attached to an alkyne-modified 5-methyl-2-(pyridin-2-yl)thiazol-4-ol yielding a fluorophore containing CD in a click-type reaction. Intermolecular complexes were formed by poly(host–guest)-interactions. The supramolecular structures were characterized by 1H NMR-ROESY spectroscopy, dynamic light scattering, UV–vis spectroscopy, fluorescence spectroscopy, and asymmetric flow field-flow fractionation. By adding potassium adamantane-1-carboxylate, the thiazol dye is displaced from the CD-cavity and the elongated noncovalent polymeric structures collapse.

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