A multifunctional near- infrared laser- triggered drug delivery system using folic acid conjugated chitosan oligosaccharide encapsulated gold nanorods for targeted chemo- photothermal therapy

The development of a new generation of multifunctional nanomaterials as a drug delivery system for chemo-photothermal therapy is of great necessity. In this study, we first prepared folic acid-conjugated and doxorubicin-loaded chitosan oligosaccharide encapsulated gold nanorods (FA-COS-TGA-GNRs-DOX) as a new photothermal agent for the delivery of drugs and heat to tumor areas. FA-COS-TGA-GNRs-DOX nanomaterials combine the advantages of COS, GNRs, FA, TGA, and DOX and have excellent biocompatibility, strong absorbance in the near-infrared (NIR) region, photostability, photothermal conversion efficiency, high targeting efficiency, fast drug release under laser irradiation, and tumor cell killing efficiency. FA-COS-TGA-GNRs-DOX exhibited significantly greater cell killing after laser irradiation. The intracellular uptake behavior of the targeted FA-COS-TGA-GNRs-DOX was confirmed by flow cytometry, two-photon fluorescence microscopy (TPFM), and confocal laser scanning microscopy (CLSM). More interestingly, the tumors in the presence of FA-COS-TGA-GNRs-DOX under laser irradiation were efficiently ablated and did not recur, showing an outstanding combined therapy of tumors. The combination of photothermal therapy (PTT) and photoacoustic imaging (PAI) could accurately locate and fully destroy tumor tissues after the intravenous injection of FA-COS-TGA-GNRs-DOX. Hence, this work offers a new avenue to develop a novel class of multifunctional nanomaterials as a drug delivery system for cancer therapy.