Kondensationsversuche mit 2,2,5,5-Tetramethyl-3,4-dithiahexandial-(1,6)

A comparative study on PVC based sensors in determination of

The proposed work described the synthesis of neutral ionophores; 4,8-diaza-3,3,10,10-tetramethyl-1,2-dithiacyclodecane (S1), 5,8-diaza-3,3,10,10-tetramethyl-1,2 dithiacyclodecane-N,N''-diacetic acid (S2) and N,N''-bis(2,2-dimethyl-2-mercaptoethyl)ethylenediamine-N,N-diacetic acid (S3) used for comparative analysis in determination of molybdenum(v) as PVC-based membrane sensors. The best result was obtained with sensor no. 7 based on S3 ionophore with membrane composition (w/w, mg%); 5.0(S) : 30.0(PVC) : 5.0(KTpClPB) : 60.0(o-NPOE) showing a working range of 2.3 × 10-7-1.0 × 10-2 M with a detection limit of 1.2 × 10-7 M and a toleration of non-aqueous media up to 15% with slope of 11.7 mV/decade of activity. The sensor no. 7 can also be used to assess the Mo(v) concentration in different natural samples (water bodies, soils, root nodules and urine samples) with comparative analysis of ETAAS and spectrophotometric methods. The proposed sensor no. 7 can be used 2.5 months without any distortion in results after that leaching of ionophore was observed from the membrane phase in aqueous solutions of Mo(v). The proposed sensor has shown a good dynamic response time of 11 s.

Lipiodol solution of a lipophilic agent, (188)Re-TDD, for the treatment of liver cancer

Radiolabeled lipiodol has been used for targeting liver cancer. We developed a lipiodol solution of (188)Re-TDD (2,2,9,9-tetramethyl-4,7-diaza-1,10-decanedithiol) and investigated its feasibility for the treatment of liver cancer. The lipiodol solution of (188)Re-TDD was well-retained in the lipiodol phase in vitro. After injection through the tail veins of mice, high lung-uptake was investigated which is evidence of embolizing activity. We also found high accumulation in hepatoma after injection through the hepatic arteries of hepatoma-bearing rats. In conclusion, the lipiodol solution of (188)Re-TDD is a promising agent for liver cancer therapy.

The use of diaminodithiol for labeling small molecules with technetium-99m

To investigate the labeling of small molecules with 99mTc by the bifunctional chelate approach, we have synthesized both a fatty acid and an estrone derivative containing a chelator of the N2S2 type. In the case of the fatty acid, this was a diaminodithiol (DADT) while for the estrone, a diaminodisulfide (DADS) was attached. The estrone derivative (5-(2-methylene estrone 3-methyl ether)-3,3,10,10-tetramethyl-1,2-dithia-5,8-diazacyclodecane hydrochloride, DADS-E) was prepared by alkylation of DADS while the fatty acid derivative (N-(11-undecanoic acid)-N,N'-bis(2-methyl-2-mercaptopropyl) ethylenediamine hydrochloride, DADT-FA) was synthesized by alkylation of DADS followed by reduction. DADS-E was labeled in ethanol at elevated temperatures while DADT-FA was labeled at room temperature, both by stannous reduction. Paper chromatography showed both to be labeled and reverse-phase HPLC showed multiple peaks for both. Serum stability studies were performed by incubation at 37 degrees C with aliquots removed at 1 min and 1 day for analysis by size-exclusion HPLC. Initially, little pertechnetate or binding to serum proteins was observed whereas after 1 day the majority of activity in both cases was protein bound with 20 and 38% pertechnetate appearing for DADT-FA and DADS-E respectively. In conclusion, small biologically active molecules may be labeled with 99mTc through an attached diaminodithiol or diaminodisulfide group.

Serum stability and non-specific binding of technetium-99m labeled diaminodithiol for protein labeling

Previously we investigated the use of DTPA-coupled proteins to simplify labeling with 99mTc but especially to improve the stability of the label. These investigations have now been extended to include several N2S2 ligands such as N,N'-bis(2-methyl-2-mercaptopropyl)ethylenediamine (DADT) and a novel ligand of similar structure with a propylene bridge between two amines, 2-hydroxy-N,N'-bis(2-methyl-2-mercaptopropyl)propylenediamine++ + (DADT-3C-2OH). The condition of labeling of free ligand (pH, buffer and tin concentration) was optimized to provide 100% chelation with 99mTc at reasonable ligand concentrations (100 micrograms/mL or less). Labeling was determined by paper chromatography, reverse-phase and size-exclusion HPLC. After incubation in fresh serum, 37 degrees C for 24 h, repeat analysis showed less than 5% dissociation of the chelate. By contrast, the DTPA chelate shows instability towards oxidation during this period. DADT derivatized on an ethylene carbon showed almost identical serum stability as DADT itself whereas when derivatized on a nitrogen greater instabilities were apparent. Using identical labeling conditions, free DADT was chelated in the presence of IgG at different ligand: protein molar ratios. Non-specific binding of 99mTc to IgG at a 10:1 DADT-HM:IgG molar ratio was as little as 5% and was essentially zero at a 2:1 DADT:IgG molar ratio when labeling was by transcomplexation from 99mTc-EDTA. The DADT-3C-2OH ligand showed superior performance both in regard to serum stability and the absence of non-specific binding. In conclusion, the N2S2 ligands form more stable chelates with 99mTc than does DTPA with reduced non-specific binding and may therefore represent an attractive alternative for labeling proteins with 99mTc by the bifunctional chelate approach.