Modulation of Molecular Structure and Mechanical Properties of κ-Carrageenan-Gelatin Hydrogel with Multi-Walled Carbon Nanotubes

Abstract

Hydrogels, three-dimensional hydrophilic water-insoluble polymer networks having mechanical properties inherent for solids, have attracted continuous research attention over a long time period. Here, we studied the structure and properties of hydrogel based on gelatin, κ-carrageenan and CNTs using the combination of SAXS, PXRD, AFM microscopy, SEM and rheology methods. We have shown that the integration of polysaccharide and protein in the composite hydrogel leads to suppression of their individual structural features and homogenization of two macromolecular components into a single structural formation. According to obtained SAXS results, we observed the supramolecular complex, which includes both polysaccharide and protein components associated with each other. It was determined that hydrogel structure formed in the initial solution state (dispersion) retains hydrogel supramolecular structure under its cooling up to gel state. The sizes of dense cores of these polyelectrolyte complexes (PEC) slightly decrease in the gel state in comparison with PEC water dispersion. The introduction of CNTs to hydrogel does not principally change the type of supramolecular structure and common structural tendencies observed for dispersion and gel states of the system. It was shown that carbon nanotubes embedded in hydrogel act as the supplementary template for formation of the three-dimensional net, giving additional mechanical strengthening to the studied system.

Characterization and Fabrication of Xerogel Polymeric Nanocomposites and Multifunctional Applications

“…On drying of -carrageenan@gelatin HDG, essential for the AFM experiment, from (Figure 25 a) the formation of the biopolymeric architecture is observed, referred as the biopolymeric scaffold [29]. For this composite HDG, the berous substrate initiating the gel formation are short when compared with those of pristine carrageenan solution (Figure 25 b) with a thickness of about 30 nm.…”

“…The AFM image (Figure 25 c) is comprised of a network architecture of miniaturized aggregates within range of 70-100 nm in size. The AFM revealed that the nanotubes are evenly dispersed, being packed and in wrapping with biopolymeric matrices [29].…”

“…Figure 24 XRD curves garnered from dry original parts (a) of HDG and time evolution of XRD ofcarrageenan@gelatin HDG when dried with and without CNTs (b) SEM images showing that the specimens are in a uniform state with a smoothly surface (c) [29].…”

“…Figure 25 X-G (dried HDG) AFM images lms and corresponding 3-D surface visualization of specimens of pristine -carrageenan@gelatin HDG (a) and this HDG with CNTs (c). Film from 0.8 wt.% -carrageenan solution (b) is presented for a comparative examination [29].…”

κ-Carrageenan Hydrogel as a Matrix for Therapeutic Enzyme Immobilization

“…Proteins, possessing a positive net charge, form the coacervates with anionic polysaccharides. As we recently demonstrated on the example of lysozyme and κ-carrageenan coacervates [ 15 ], such interactions significantly modify the protein structure during the formation of bicomponent junctions and the common protein–polysaccharide structure [ 16 ]. On the other hand, the negatively charged globular proteins, trapped in the matrix of anionic polysaccharides upon the fast termination of the gelation process, usually retain their functional structure [ 2 ].…”