This research is aimed to develop a kind of hollow nanosphere based on β-cyclodextrin-grafted α, β-poly(aspartic acid) (β-CD-graft-PAsp) as drug carrier to enhance the stability of camptothecin (CPT) in aqueous media. Firstly, mono(6-(2-aminoethyl) amino-6-deoxy)-β-cyclodextrin (β-CDen) was synthesized by a substitution reaction between mono-6-deoxy-6-(p-tolylsulfonyl)-β-cyclodextrin (6-OTs-β-CD) and ethylenediamine; and then, the five-member rings in poly(L-succinimide) (PSI) were successively opened by β-CDen to obtain β-CD-graft-PAsp. The synthesized β-CD-graft-PAsp was found to form the unique hollow nanosphere with the internal hole of about 17 nm and many β-CD cavities of 0.7 nm interspersed on the shell. The drug-loading behavior of the hollow nanosphere was also evaluated by using CPT as guest molecule of β-CD. It was worth of note that the β-CD-graft-PAsp hollow nanosphere as carrier enhanced the stability of CPT in aqueous media, and the CPT from the β-CD-graft-PAsp hollow nanosphere displayed a sustained release profile and hence resulted in the essential decrease of cytotoxicity to L929 cell line. Furthermore, almost no cytotoxicity of the β-CD-graft-PAsp is desirable for the application of drug carrier. As a result, the β-CD-graft-PAsp hollow nanosphere showed a great potential as the carrier of CPT.
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