The molecular recognition of β-cyclodextrin modified CdSe quantum dots with tyrosine enantiomers: Theoretical calculation and experimental study

In the present work, the molecular recognition of mono-(6-mercapto)-β-cyclodextrin modified CdSe quantum dots (β-CD/CdSe QDs) with tyrosine enantiomers were investigated with theoretical calculation and fluorescence spectroscopy. The inclusion processes and the most probable structures of the inclusion complexes were simulated using PM3 energy scanning and optimization method. The trends of stability of the two inclusion complexes deduced from their calculated stabilization energies were studied. Moreover, the fluorescence spectra of β-CD/CdSe QDs in the presence of tyrosine enantiomers as well as the effect of ionic strength on the complexation of β-CD/CdSe QDs-tyrosine were discussed. The experimental results indicated that the β-CD/CdSe QDs have better enantioselectivity to l-tyrosine than that to d-tyrosine, and good linearity between the fluorescence intensity of β-CD/CdSe QDs and l-tyrosine over the concentration range from 0.10 × 10−4 mol/L to 4.00 × 10−4 mol/L with relative coefficient of 0.9909 was obtained. The experimental data agrees well with that obtained from theoretical calculation, indicating that β-cyclodextrin modified CdSe quantum dots contained good inclusion capability and fluorescence property, it has good potential application in the field of biological diagnosis, analysis, etc.