Molecular characteristics of kappa-selenocarrageenan and application in green synthesis of silver nanoparticles

Selenium is an essential trace element in human body, and kappa-selenocarrageenan (Se-car) is an organic source of selenium supplement. To further utilize Se-car in food packaging, biotherapy or biosensor, the molecular information of Se-car was characterized here and multi-functional Ag NPs synthesized by Se-car were fabricated. Results of GPC-MALLS, FTIR, potentiometric titration, and intrinsic viscosity showed that Se-car was polymerized by nearly 22 basic units of disaccharide. Sixty-four percentage of sulfated groups (SO₄ ²⁻) in carrageenan was replaced by selenium acid (SeO₃ ²⁻), which belonged to weak acid resulting from a gradually decrease of ζ-potential with acidity process to pH 1.0. Besides, the capacity of biosynthesis silver nanoparticles (Ag NPs) by Se-car was studied and it made a comparison with κ-carrageenan. Results exhibited that Se-car could serve as an efficient reducing and capping agent for Ag NPs fabrication (remarked as Se-car@Ag). The k_app of Se-car@Ag NPs for catalyzing 4-NP degradation was 2.14 × 10⁻² s⁻¹. Antibacterial test revealed Se-car@Ag had an ability to inhibit the growth of Escherichia coli and Staphylococcus aureus. To combine the selenium health benefit and functional metal nanoparticles, Se-car@Ag might have potential applications in multiple areas like medicine, disease diagnostic, and drug delivery.