ABSTRACT
The relaxivity of MRI contrast agents can be increased by increasing the size of the contrast agent and by increasing concentration of the bound gadolinium. Large multi-site ligands able to coordinate several metal centres show increased relaxivity as a result. In this paper, an "aza-type Michael" reaction is used to prepare cyclen derivatives that can be attached to organosilicon frameworks via hydrosilylation reactions. A range of organosilicon frameworks were tested including silsesquioxane cages and dimethylsilylbenzene derivatives. Michael donors with strong electron withdrawing groups could be used to alkylate cyclen on three amine centres in a single step. Hydrosilylation successfully attached these to mono-, di-, and tri-dimethylsilyl-substituted benzene derivatives. The europium and gadolinium complexes were formed and studied using luminescence spectroscopy and relaxometry. This showed the complexes to contain two bound water moles per lanthanide centre and T1 relaxation time measurements demonstrated an increase in relaxivity had been achieved, in particular for the trisubstituted scaffold 1,3,5-tris((pentane-sDO3A)dimethylsilyl)benzene-Gd3. This showed a marked increase in the relaxivity (13.1 r1p/mM-1s-1).
Subject(s)
Contrast Media/chemistry , Europium/chemistry , Gadolinium/chemistry , Organosilicon Compounds/chemistry , Benzene Derivatives/chemistry , Contrast Media/chemical synthesis , Coordination Complexes/chemical synthesis , Coordination Complexes/chemistry , LigandsABSTRACT
There are over 2.6 million users of e-cigarettes in the United Kingdom alone as they have been promoted as a safer alternative to traditional cigarettes. The addition of flavours and aromas has also proven to be popular with younger generations. In this review, we survey the range of studies in the short timeframe since e-cigarettes reached the market to draw attention to the health associated risks and benefits of their introduction. We complement this review with a case study reporting on the composition of selected e-cigarette refills with particular emphasis on the toxicological activity of its components on lung cells.
Subject(s)
Bronchi/drug effects , Electronic Nicotine Delivery Systems , Epithelium/drug effects , Flavoring Agents/toxicity , Smoking/adverse effects , Animals , Cell Line , Disease Models, Animal , Dose-Response Relationship, Drug , Flavoring Agents/analysis , Glycerol/analysis , Glycerol/toxicity , Humans , Inhibitory Concentration 50 , Liver/drug effects , Lung/drug effects , Metals/analysis , Metals/toxicity , Mice , Nicotine/analysis , Nicotine/toxicity , Propylene Glycol/analysis , Propylene Glycol/toxicity , United KingdomABSTRACT
Childhood bone cancer though rare, has very limited treatment choices, with poor survival rates and often involving amputation. We developed a novel molecule, 2', 4'-dihydroxy-dithion-dibenzoyl-methane and tested it on hepatic, colon, lung and osteoblast cancer cell lines. Thionylation of 2', 4'- dihydroxydibenzoylmethane led to selective targeting of bone cancer cells, stopping their growth and leading to their death without affecting non-cancerous cells within the bone marrow or other non-malignant cells.