Novel micro/nanomotors for tumor diagnosis and therapy: Motion mechanisms, advantages and applications

The lack of effective diagnostic and therapeutic techniques is a crucial cause of the high clinical mortality for malignancy. Notably, self-propelled micro/nanomotors are expected to address the drawbacks of conventional nanoparticles in tumor diagnosis and therapy. The special locomotion property ensures the high efficiency of micro/nanomotors in term of rapid distribution, deep penetration, and targeted delivery. Hence, in this review, the motion mechanism and the controllability of speed and direction of the micro/nanomotors were described, as well as the advantages regarding the enhancement of biological barrier crossing (overcoming blood flow obstacles, tumor microenvironment barriers), targeting delivery and deep penetration in the tumor. The most recent advances in micro/nanomotor contributions were comprehensively summarized to various medical imaging technologies, biosensing techniques, and therapeutic approaches, especially for the combination therapy and integration of diagnosis and treatment based on multifunctional micro/nanomotors. Furthermore, challenges for developing practical micro/nanomotors were discussed along with future directions from the clinicians' perspective, which is promised to speed up the clinical translation process and contribute to efficient tumor diagnosis and therapy.