A multifunctional ternary Cu(II)-carboxylate coordination polymeric nanocomplex for cancer thermochemotherapy

Metal-based photothermal therapy has been widely used in the biomedicine field and includes gold nanoparticles, silver nanoparticles and copper sulfide nanoparticles. Furthermore, the coordination bonding-based metal nanocomplex is a new generation of photothermal agents for cancer therapy due to its high photothermal transduction efficiency, good biocompatibility, biodegradation and bioactivity. In this study, we designed a coordination bonding-based copper (Cu(II))-carboxylate ternary architecture, which consists of a conjugate dopamine-modified nontoxic hyaluronic acid, copper ions and citric acid. When the Cu(II) coordinated with the carboxyl groups, the splitting d orbitals energy gap of Cu(II) and the capability of electron transition were enhanced, which can increase the extinction ability in the near-infrared region for enhancing photothermal therapy. Moreover, the degradation of hyaluronic acid by hyaluronidase highly expressed in the tumor microenvironment led to the release of Cu-citric acid complexes, thus exhibiting an additional chemotherapeutic effect. The nanocomplexes possessed high-performance photothermal conversion, determined to be 21.3%. The solution could be easily heated to above 42 °C, which was sufficient to ablate the cancer cells. An obvious decrease in cell viability was observed in B16F10 cells incubated with the nanocomplexes under laser at the lower concentration of 20 μg/mL Cu(II). Upon near-infrared laser irradiation, the nanocomplexes showed high photothermal therapy and chemotherapeutic efficacy for breast cancer in vivo. This study demonstrated that the Cu(II)-carboxylate coordination nanocomplex is a promising new effective and facilely prepared thermochemotherapy agent for combination therapy against cancer.