Diagnosis and localization of bacterial infections remains a significant clinical challenge. Harnessing bacteria-specific metabolic pathways, such as the maltodextrin transport mechanism, may allow specific localization and imaging of small or hidden colonies. This requires that the intrabacterial tracer accumulation provided by the transporter is matched by high serum stability of the tracer molecule. Herein, radiolabeled maltodextrins of varying chain lengths and with free nonreducing/reducing ends are reported and their behavior against starch-degrading enzymes in the blood, which compromise their serum stability, is evaluated. Successful single-photon emission computed tomography (SPECT) imaging is shown in a footpad infection model in vivo by using the newly developed model tracer, [ Tc]MB1143, and the signal is compared with that of F-fluorodeoxyglucose positron emission tomography ([ F]FDG-PET) as a nonbacterial specific marker for inflammation. Although the [ Tc]MB1143 imaging signal is highly specific, it is low, most probably due to insufficient serum stability of the tracer. A series of stability tests with different F-labeled maltodextrins finally yielded clear structural guidelines regarding substitution patterns and chain lengths of maltodextrin-based tracers for nuclear imaging of bacterial infections.

Single site OH → F substitution at the termini of maltotetraose leads to significantly improved hydrolytic stability towards α-amylase and α-glucosidase relative to the natural compound. To explore the effect...

Gangliosides are intimately involved in a plenum of (neuro)­inflammatory processes, yet progress in establishing structure–function interplay is frequently hindered by the availability of well-defined glycostructures. Motivated by the ubiquity of the ganglioside GM3 in chemical neurology, and in particular by its conspicuous presence in myelin, the GM3 epitope was examined with a view to preclinical validation as a tracer. The suitability of this scaffold for the noninvasive imaging of oligodendrocyte differentiation in Multiple sclerosis is disclosed. The stereocontrolled synthesis of a site-selectively fluorinated analogue (F–GM3) is also disclosed to enable a comparative analysis in oligodendrocyte (OL) differentiation. Whereas the native epitope caused a decrease in the viability in a dose-dependent manner, the addition of distinct F–GM3 concentrations over 48 h had no impact on the OL viability. This is likely a consequence of the enhanced hydrolytic stability imparted by the fluorination and highlights the potential of fluorinated glycostructures in the field of molecular imaging. Given the predominant expression of GM3 in oligodendrocytes and the capacity of GM3 to interact with myelin-associated proteins, this preclinical evaluation has revealed F–GM3 to be an intriguing candidate for neurological imaging.

Sialic acids are conspicuous structural components of the complex gangliosides that regulate cellular processes.