NIR-Activated Polydopamine-Coated Carrier-Free "Nanobomb" for In Situ On-Demand Drug Release.

Carrier-free nanoparticles with high drug loading have attracted increasing attention; however, in situ on-demand drug release remains a challenge. Here, a novel near-infrared (NIR) laser-induced blasting carrier-free nanodrug delivery system is designed and fabricated by coating doxorubicin (DOX) nanoparticles (DNPs) with a polydopamine film (PDA) that would prolong the blood circulation time of DNPs and avoid the preleakage of the DOX during blood circulation. Meanwhile, the NH(4)HCO(3) is introduced to trigger in situ "bomb-like" release of DOX for the production of carbon dioxide (CO(2)) and ammonia (NH(3)) gases driven by NIR irradiated photothermal effect of PDA. Both in vitro and in vivo studies demonstrate that the carrier-free nanovectors with high drug loading efficiency (85.8%) prolong tumor accumulation, enhance chemotherapy, achieve the synergistic treatment of chemotherapy and photothermal treatment, and do not induce any foreign-body reaction over a three-week implantation. Hence, the delicate design opens a self-assembly path to develop PDA-based NIR-responsive multifunctional carrier-free nanoparticles for tumor therapy.