Folic acid-conjugated raloxifene-loaded graphene-based nanocarrier: Fabrication, characterization and antitumor screening

Breast cancer is the second leading cause of cancer death among women. The efficacy of most current therapies is compromised by the development of drug resistance and/or lack of target site specificity. Graphene nanoribbons (GNRs) represent one of the emerging graphene-based nanocarriers that show high target specificity and efficient cellular internalization for cancer cells. Herein, we screened the potential antitumor activity of a nanocarrier based on graphene oxide and folic acid and loaded with the selective estrogen receptor modulator, raloxifene hydrochloride (RXF), on breast cancer cells. Oxidized graphene nanoribbons (OGNRs), obtained by longitudinal unzipping technique, were functionalized with folic acid (FA), and were loaded with RXF. The prepared RXFloaded OGNRs-FA showed a multi-layered structure with loading efficiency and entrapment efficiency of 37% and 56%, respectively. In vitro release revealed a pH-dependent release of RXF from OGNRs. Cytotoxicity screening of RXF-OGNRS-FA was investigated for two breast cancer cell lines; MCF-7 and MDA-MB-231. RXFloaded OGNRs-FA exerted dose- and time-dependent effects against both breast cancer cells. Confocal microscopy imaging showed that surface functionalization of OGNRs with FA remarkably enhanced cellular uptake of OGNRs by both cell lines relative to non-functional OGNRs. Collectively, OGNRs-FA may represent an appealing nanomaterial that mediates cell-specific drug delivery to breast cancer cells. However, a thorough investigation of the in vivo fate and long-term toxicity of OGNRs-FA remains to be elucidated prior their full utilization in biomedical applications.