Cyclodextrin Dimers Functionalized with Biotin as Nanocapsulesfor Active Doxorubicin Delivery against MCF‐7 Breast Cell Line

Cyclodextrin dimers have been investigated as potential nanocapsules of biomolecules. The presence of two cavities can improve the stability of inclusion complexes, working as a hydrophilic sandwich of poorly water‐soluble species. Here, we designed new β‐ and γ‐cyclodextrin dimers functionalized with biotin as a targeting unit and tested the new bioconjugates as doxorubicin delivery systems in cancer cells. Biotin can recognize the Sodium‐dependent Multivitamin Transporter (SMVT) receptor, encoded by the Solute Carrier Family 5 Member 6 (SLC5A6) gene and improve the uptake of drugs. We evaluated the expression of the SLC5A6 transcript in human cell lines to select the best cell model (MCF‐7) for the in vitro studies. Furthermore, in the cell lines, we investigated the transcript levels of genes correlated to biotin cell availability, Holocarboxylase Synthetase (or HCS encoded by HLCS gene) and Biotinidase (encoded by BTD gene) enzymes. Moreover, the expression of ATP Binding Cassette Subfamily G Member 2 transporter (encoded by ABCG2 gene), which may play a role in doxorubicin resistance, has been investigated. The antiproliferative activity of the doxorubicin complexes with the dimers has been determined to study the effect of the biotin moiety on the cytotoxicity in MCF‐7 cancer cells.