A new water-soluble and lipid-insoluble spin probe: application to the study of aqueous sucrose solutions
✍ Scribed by Peter S. Belton; Leslie H. Sutcliffe; Duncan G. Gillies; Xiaoping Wu; Alex I. Smirnov
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 125 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
A new ESR spin probe, sodium 1,1,3,3-tetrakis(trideuteromethyl)isoindolin-2-yloxyl-4-sulphonate, which is related to the extensively studied generic free radical 1,1,3,3-tetramethylisoindolin-2-yloxyl (TMIO), was synthesized. The latter has greater chemical and biochemical stability than any other nitroxyl radical and in lowviscosity media it exhibits near isotropic tumbling motion. It is therefore a very useful spin probe for ESR investigations of (i) microviscosity, (ii) measurements of oxygen concentrations and rates of oxygen di †usion and (iii) ESR imaging experiments. Substituents can be introduced into the basic TMIO radical : here the synthesis of the sulphonated form is described ; it has a very high solubility in water, which is important for in vivo biological applications where a low-volume, high-concentration spin probe may need to be injected. In this paper, its use is demonstrated in a study of the microviscosities of aqueous sucrose solutions at concentrations up to 65% and over a range of temperatures. General assumptions were tested concerning the e †ect of inhomogeneous broadening from unresolved proton hyperÐne coupling constants on the calculations of rotational correlation times. For this purpose, the well known spin probes FremyÏ salt (peroxylamine disulphonate) and di-tert-butyl nitroxide were used. The ESR results are compared with those from previous NMR relaxation studies of aqueous sucrose solutions.
John Wiley & Sons, Ltd.