We study colloids of nanobiocomposites (NBC) containing Au nanoparticles (NP) obtained by reduction of gold precursor with functional groups of κCAR. The AuNPs content was changed from 2.0 to 5.6 w/w %. Hydrolysis of κCAR during reduction of gold ions produced carboxylate groups supporting nanobioconjugation (FT-IR data) and electrostatic stabilization through increased negative ζ-potential. The self-assembly of AuNPs took place after storing NBC, as shown by UV/vis. extinction and transmission electron microscopy. Analysis of the structure-sensitive Rg/Rh ratios obtained by dynamic and static light scattering showed that the colloids have core-shell structure. The macromolecules in the shell exhibited polyelectrolyte expansion at [NaCl] and [KCl] < 0.02 M. Above 0.02 M, the difference between non-specific sodium and specific potassium ions on the shell thickness was registered. The temperature hysteresis of the hydrodynamic radius Rh was similar to that of the pristine κCAR observed previously by optical rotation. Monitoring the equilibration of light scattering intensity at each mini-quenching step of the cooling run allowed further insight into the hysteresis origin. These colloids are interesting for sensing applications because of enhanced scattering of plasmonically coupled AuNPE. Their thermo- and ion-sensitivity can be useful in drug delivery.
Keywords: Light scattering; Nanobiocomposite colloids; κ-Carrageenan.
Copyright © 2019 Elsevier B.V. All rights reserved.