M H Sørensen | PubMed Health

PubMed2005

Optical biosensor with dispersion compensation.

Dispersion limits performance in many optical systems. In surface plasmon resonance (SPR) biosensors, the sensing area is an optical element in which the dispersion depends on the effective refractive index of the biochemical compounds to be measured. We report a method of compensating for wavelength dispersion in SPR biosensors employing two integrated diffractive optical coupling elements in a polymer substrate. The dispersion compensation is achieved over the whole dynamic measurement range and provides a biosensor more robust to wavelength fluctuations than prism-coupler SPR systems. The concept can readily be employed in other types of sensor measuring refractive-index changes.

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PubMed2001

Synthesis of a bicyclic analogue of AZT restricted in an unusual O4'-endo conformation.

The [3.2.0]bicyclic beta-nucleoside analogue 5 has been designed as a conformationally restricted analogue of the anti-HIV drug AZT. The synthesis of 5 as well as its alpha-anomer 29 is hereby described. The synthesis was accomplished from D-arabinose via a modified Corey-Link procedure stereoselectively incorporating the azide moiety as well as a methyl ester function. When the tert-butyldiphenylsilyl group was used as a permanent protecting group, a selective formation of an oxetane ring failed. When using the p-methoxyphenyl group as a permanent protecting group, 5 and 29 were efficiently obtained via a selective reduction of the ester, a nucleobase coupling followed by separation of the anomers and ring-closing procedures. The nucleoside 5 is conformationally restricted in an unusual O4'-endo (East) conformation, which is an intermediate between the North- and South-type conformations. Nevertheless, neither 5 nor 29 displayed any anti-HIV activity.

Anti-HIV Agents↗