Fully automated 18F-fluorination of N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB) for indirect labelling of nanobodies.

N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB), a widely used labeling agent to introduce the 4-[18F]fluorobenzoyl-prosthetic group, is normally obtained in three consecutive steps from [18F]fluoride ion. Here, we describe an efficient one-step labeling procedure of [18F]SFB starting from a tin precursor. This method circumvents volatile radioactive side-products and simplifies automatization. [18F]SFB was obtained after HPLC purification in a yield of 42 + 4% and a radiochemical purity (RCP) > 99% (n = 6). In addition, we investigate the automation of the coupling of [18F]SFB to a nanobody (cAbBcII10, targeting ß-lactamase enzyme) and purification by size exclusion chromatography (PD-10 desalting column) to remove unconjugated reagent. Production and use of [18F]SFB were implemented on a radiosynthesis unit (Neptis®). The fully automated radiosynthesis process including purification and formulation required 160 min of synthesis time. [18F]SFB-labeled nanobody was obtained in a yield of 21 + 2% (activity yield 12 + 1% non-decay corrected) and a radiochemical purity (RCP) of > 95% (n = 3). This approach simplifies [18F]SFB synthesis to one-step, enhances the yield in comparison to the previous report and enables the production of radiolabeled nanobody on the same synthesis module.

Sphingomyelin-Based Nanosystems (SNs) for the Development of Anticancer miRNA Therapeutics.

Gene replacement therapy with oncosuppressor microRNAs (miRNAs) is a promising alternative to interfere with cancer progression. However, miRNAs are highly inefficient in a biological environment, hampering a successful translation to clinics. Nanotechnology can tackle this drawback by providing delivery systems able to efficiently deliver them to cancer cells. Thus, the objective of this work was to develop biocompatible nanosystems based on sphingomyelin (SM) for the intracellular delivery of miRNAs to colorectal cancer cells. We pursued two different approaches to select the most appropriate composition for miRNA delivery. On the one hand, we prepared sphingomyelin-based nanosystems (SNs) that incorporate the cationic lipid stearylamine (ST) to support the association of miRNA by the establishment of electrostatic interactions (SNs-ST). On the other hand, the cationic surfactant (DOTAP) was used to preform lipidic complexes with miRNA (Lpx), which were further encapsulated into SNs (SNs-Lpx). Restitution of miRNA145 levels after transfection with SNs-Lpx was related to the strongest anticancer effect in terms of tumor proliferation, colony forming, and migration capacity assays. Altogether, our results suggest that SNs have the potential for miRNA delivery to develop innovative anticancer therapies.

Radiolabelling of lipid-based nanocarriers with fluorine-18 for in vivo tracking by PET.

Organic nanoparticles made out of biodegradable and biocompatible materials have attracted increased attention in the therapeutic and diagnostic fields. In this study, we attempted to explore a new radiolabelling chelating free strategy for biodegradable sphingomyelin nanometric emulsions with fluorine-18 (18F), a radioisotope regularly used in clinic. [18F]fluoride was produced by the cyclotron and was incorporated into 4-[18F]fluorobenzamido-N-ethylmaleimide ([18F]FBEM), which was coupled next to the emulsions previously functionalized with a thiol group, via inclusion of either a thiol-PEG-lipid (SH-PEG12-C18), or a peptide-PEG-lipid (Cys-Pro-Ile-Glu-Asp-Arg-Pro-Met-Cys-PEG8-C18) derivative. Radiolabelled emulsions were obtained in a rapid and efficient fashion through facile-conjugated chemistry without the use of organic solvents, and characterized in terms of size, polydispersity, surface charge, pH, and osmolarity. PET imaging and biodistribution studies in BALB/c mice allowed obtaining the pharmacokinetics of the radiolabelled emulsions and determining the clearance pathways. Altogether, we confirmed the potential of this new technique for the radiolabelling of lipid-based drug nanosystems for application in PET imaging diagnosis.