Co-delivery of icariside II and doxorubicin by self-assembled carrier-free nanofibers for anti-lung cancer therapy

Icariside II (ICAII), a bioactive compound derived from Epimedii Folium, exhibits promising anti-tumor activity but encounters challenges in its clinical application due to its poor solubility and low bioavailability. Thus, this study developed a novel carrier-free co-delivery system of ICAII and doxorubicin (DOX) through their self-assembly into nanofibers. ICAII combined with DOX nanofibers (ICAII-DOX NFs), and ICAII-DOX/TPGS NFs (with TPGS as a stabilizer) were systematically characterized for their physicochemical properties, including size distribution, morphology, and molecular interactions. The synergistic anti-lung cancer effect of ICAII and DOX was evaluated <i>in vitro</i> and <i>in vivo</i>. The prepared ICAII-DOX NFs and ICAII-DOX/TPGS NFs showed mean sizes of 127 and 338 nm, respectively, with PDI values of 0.2-0.3 and drug loading contents of >48%. FTIR, fluorescence, NMR and X-ray powder diffraction analyses revealed that the formation of ICAII-DOX co-assembly was primarily driven by intermolecular hydrogen bonding between the two molecules. The nanofibers demonstrated controlled drug release profiles (cumulative release rate of DOX was 65.88% at 48 h, and cumulative release rate of ICAII was 74.29% at 48 h) and enhanced cellular uptake (1.8-fold more than that of the free DOX group). CCK-8 assay results showed that the IC₅₀ values (calculated in terms of DOX) of the ICAII-DOX mixture, ICAII-DOX NFs and ICAII-DOX/TPGS NFs were 0.67, 0.60 and 0.44 μM in A549 human lung carcinoma cells, respectively. <i>In vivo</i> studies using an A549 xenograft mouse model showed the improved therapeutic efficacy of the co-delivery system (the inhibition rate of the ICAII-DOX mixture and ICAII-DOX/TPGS NF groups was 29.90%) compared with single drug treatment (the inhibition rates of the DOX and ICAII groups were 8.70% and 17.72%, respectively). This study presents a self-assembled carrier-free co-delivery system, providing a potential strategy for treating lung cancer.