Designing a pH-responsive drug delivery system for the release of black-carrot anthocyanins loaded in halloysite nanotubes for cancer treatment

Anthocyanins extracted from black-carrot were encapsulated into halloysite nanotubes (HNT) as a potential carrier for the first time. Anthocyanins were loaded into HNT under vacuum conditions. TEM images indicated the successful entrance of anthocyanins into the lumen of HNT. Anthocyanins loading efficiency was determined to be 4% using thermogravimetric analysis (TGA). XRD patterns showed that all reflections shifted to higher values for HNT loaded with anthocyanins compared to pure HNT which indicates reduced d-value of the crystalline forms. In vitro release of anthocyanins was studied under gastrointestinal conditions using the pH-differential method. The drug release from HNT was modeled and based on R-2 values, the Korsmeyer-Peppas model was introduced as the best model predicting the release behavior. Cytotoxic effects of the samples against MCF-7 human breast cancer and HT-29 colon cancer cell lines were evaluated using SRB assay. The cell viability was reduced by 2 folds against anthocyanins-loaded HNT compared to pure anthocyanins in both cell lines. Anthocyanins-loaded HNT is suggested as a promising pH-responsive drug delivery system for the treatment of cancer.