Synthesis and Characterization of λ-Carrageenan Oligosaccharide-Based Nanoparticles: Applications in MRI and In Vivo Biodistribution Studies

λ-type carrageenan (λ-CAR) polysaccharides remain overlooked in the preparation of medical nanoparticles (NP) due to their unsuitable rheological properties and undesired biological effects, although they can also offer advantageous properties. To overcome these obstacles, oligosaccharide derivatives (λ-COS) have been successfully applied to the synthesis of stable NP incorporating both, ferrite cores and divalent manganese (Mn2+) releasable ions. The acute pro-inflammatory behavior and anticoagulant activity of native λ-CAR were significantly reduced in the case of λ-COS and λ-COS NP, rendering possible their use for medical applications. In vivo MRI studies in mice showed that the λ-COS NP framework is promising for two applications. The first is partial Mn2+ release into the plasma to achieve intracellular Mn2+-based contrast of the myocardium and imaging of the hepatobiliary system. Second, it serves as a novel sugar-based coating that confers suitable pharmacokinetic properties to NP, making it promising for further targeted therapy applications.