Tailoring Alginate Hydrogels via Precoordinated Lanthanide Complexes as Dynamic Cross-Linkers

Area of Science:

• Materials Science
• Polymer Chemistry
• Inorganic Chemistry

Background:

• Lanthanides are explored as ionic cross-linkers for hydrophilic polymers to create luminescent hydrogels.
• Existing lanthanide-complexed networks often suffer from poor mechanical robustness.
• Developing mechanically stable luminescent hydrogels remains a significant challenge.

Purpose of the Study:

• To introduce precoordinated lanthanide complexes as dual-function cross-linkers and luminophores.
• To fabricate mechanically stable alginate hydrogels using these complexes.
• To investigate the influence of lanthanide ionic size on hydrogel properties.

Main Methods:

• Synthesis of three types of precoordinated lanthanide complexes (Tb³⁺, Eu³⁺, Sm³⁺).
• Spontaneous cross-linking of alginate with these complexes via electrostatic interactions.
• Characterization of the resulting alginate-lanthanide (Alg-Ln) hydrogels, including mechanical strength and gelation time.

Main Results:

• All three types of complexes successfully formed Alg-Ln hydrogels.
• Alg-Sm hydrogel demonstrated significantly shorter gelation time and superior mechanical strength compared to Alg-Eu and Alg-Tb hydrogels.
• The enhanced properties of Alg-Sm hydrogel are attributed to the larger ionic volume of the samarium complex, promoting denser cross-linking.

Conclusions:

• Precoordinated lanthanide complexes are effective in creating mechanically robust and luminescent alginate hydrogels.
• Lanthanide ionic size plays a crucial role in determining hydrogel network structure and mechanical properties.
• The developed hydrogels offer tunable properties for potential applications, including luminescent sensing (e.g., Alg-Eu for copper ions).