Cyclodextrin‐functionalized silica nanoparticles with dendrimer‐like spacers for enantioselective capillary electrochromatography

Abstract

In this report, β-cyclodextrin (β-CD)-functionalized silica nanoparticles (SNPs) with dendrimer-like spacers were synthesized by first grafting the SNPs with different generations of polyamidoamines (PAMAMs), followed by modifying the grafted SNPs with mono-6-deoxy-(p-tolylsulfonyl)-β-CD. The β-cyclodextrin-modified silica nanoparticle-cored PAMAMs (SNP-PAMAM-β-CDs) were studied as chiral pseudostationary phases for separating three racemic drugs, namely, chlorpheniramine, nefopam, and verapamil. The β-CD-functionalized SNPs with dendrimer-like spacers were more enantioselective than native β-CD, and the structures of the dendritic spacers were highly influential on the separation. In 20 mM NaH2 PO4 , addition of 4.00 mg/mL SNP-G1.0-β-CD (corresponding to 1.12 mM β-CD) could baseline separate the enantiomers of chlorpheniramine and nefopam, and introduction of 7.00 mg/mL SNP-G0-β-CD (corresponding to 1.68 mM β-CD) resulted in enantioseparation of the verapamil racemates. On the contrary, the enantiomers of nefopam and verapamil could not be resolved in the presence of 15 mM native β-CD. Our results suggest that SNP-PAMAM-β-CDs hold great promise for enantioselective separations.