The interaction of β-cyclodextrin with etoposide studied by fluorescence spectroscopy

The fluorescence spectroscopy and UV spectroscopy have been used to monitor the inclusion  phenomena of VP-16 with β-cyclodextrin (β-CD), together with studies concerning the effects of reaction time, temperature and concentration on this behavior.  The results show that the fluorescence intensity increased when VP-16 and β-CD forming a 1∶1 inclusion complex, which indicate that β-CD has fluorescence sensitizing effect on the VP-16.  At 22 ℃, the inclusion constant was 2.63×10⁵ L·mol⁻¹ at pH 7.0. VP-16 has maximum emission wavelength at 316 nm under the optimum conditions.  According to this, the quantitative micro-detection method of VP-16 by fluorescence spectrometry was established.  The linear regression equation was y = 1.107 89 × 10⁷x + 95.898 1, with a correlation coefficient of 0.999 9.  The detection limit was 2.094×10⁻⁷ mol·L⁻¹.