Carrier-free nanodrug: A novel strategy of cancer diagnosis and synergistic therapy

Nanoformulations with advantages in drug delivery, safety and pharmacodynamics have been booming as a promising strategy for cancer therapy. However, the traditional nanocarrier still suffers from the low drug loading capacity, potential systematic toxicity, unclear metabolism, and other uncertainties. To overcome these issues, carrier-free nanodrugs with desirable bioactivity were developed rapidly and drawn considerable attention. Meanwhile, the multifunctional self-delivery nanoarcheticture fabricated by a simple and "green" method, has significant advantages in synergistic cancer therapy and inhibition of multidrug resistant (MDR). Till now, carrier-free nanoparticles for tumor theranostics, phototherapy, chemotherapy, diagnose and synergistic therapy, have made outstanding progress. In this review, we make an integrated and exhaustive overview of lately reports on carrier-free nanodrug delivery systems formed by several active agents. We summarize the self-assembly and modified strategies, with emphasis on application superiority of carrier-free nanocrystal, and give new insight into the establishment of ideal nanosystems for cancer treatment.