Radiolabelling of peptides for PET, SPECT and therapeutic applications using a fully automated disposable cassette system.

OBJECTIVES: Radiolabelled somatostatin analogues have found wide clinical use in nuclear medicine for both diagnostic and therapeutic applications. Here, we describe the development of a fully automated synthesis system allowing radiolabelling of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-derivatized peptides with 68Ga/¹¹¹In/¹77Lu and 9°Y, meeting radiation safety and pharmaceutical requirements. MATERIALS AND METHODS: The system consists of a syringe pump, a holder for insertion of a single use multivalve cassette, a heater and a removable radiation shielding. 68Ga labelling was performed in acetate buffer and ¹77Lu, 9°Y and ¹¹¹In labelling in ascorbate buffer, respectively, followed by purification on a C18 cartridge and final sterile filtration. Cross-contamination was prevented by using disposable cassettes and also by ensuring pharmaceutical standards. Radiochemical purity (RCP) was determined by instant thin-layer chromatography on silica gel impregnated glass fibres and reversed-phase high performance liquid chromatography. RESULTS: 68Ga-DOTA-peptides were prepared with high RCP (>91%) and radiochemical yields (RCY>80% decay corrected) and 68Ge content was less than 0.0001% in all cases. Synthesis time did not exceed 30 min. ¹¹¹In, ¹77Lu and 9°Y labelling of DOTA-peptides resulted again in high yields (approximately 90%) and RCP (approximately 95%) and total synthesis time of less than 45 min. Radiation dose to fingers was considerably reduced when compared with manual labelling procedures. CONCLUSION: The described system allows fully automated, aseptic preparation of DOTA-peptides radiolabelled with different radionuclides in high radiochemical yields and pharmaceutical quality suitable for clinical application.

Acceleration of Suzuki-Miyaura- and Stille-type coupling reactions by irradiation with near-UV-A light.

Irradiation of a palladium catalyst bearing UV-A-absorbing phosphine ligands with low-intensity UV-A light leads to higher conversions of reactants at lower temperatures and an increased selectivity towards the cross-coupling product in Suzuki-Miyaura- and Stille-type reactions. The examples studied illustrate that a selective energy input into the catalyst by irradiation leads to more selective conversions under milder reaction conditions. With the availability of affordable and energy-efficient UV-A LED light sources, selective heating of the catalyst by light can be envisaged as a general strategy to increase the performance of a catalyst.

Low-melting sugar-urea-salt mixtures as solvents for Diels-Alder reactions.

Sweet solutions are obtained upon heating mixtures of simple carbohydrates, urea and inorganic salts to moderate temperatures, to give new chiral media for organic reactions.