Autonomous bacterial nanoswimmers target cancer

Injectable drug delivery systems that autonomously detect, propel towards, and ultimately treat the cancerous tissue, are the future of targeted medicine. Here, we developed a drug delivery system that swims autonomously towards cancer cells, where it releases a therapeutic cargo. This platform is based on viable bacteria, loaded with nanoparticles that contain the chemotherapeutic-antibiotic drug doxorubicin. The bacteria ferry across media and invade the cancer cells, increasing their velocity in the presence of nutrients that are present within the tumor microenvironment. Inside the cancer cells, doxorubicin is released from the nanoparticles, destroying the bacterial swimmer (antibiotic activity) and executing the therapeutic activity against the cancer cells (chemotherapeutic activity). This mode of delivery, where both the carrier and the cancer cell are destroyed, supports implementing nanoswimmers in drug delivery (Fig. 1).

Therapeutic nano-swimmers. (A) Viable bacteria, with the capacity to autonomously swim in media, are transformed into carriers of anti-cancer agents. The bacteria are loaded with nanoparticles that contain the anti-cancer and antibiotic agent doxorubicin. (B) Cancer cells secret a unique set of nutrients that are strong attractants to the bacterial swimmer. The drug-loaded bacteria swim towards and invade the cancer cell. (C) Inside the cell, the drug releases from the nanoparticle, killing the bacteria and destroying its envelope. Following bacterial death the doxorubicin executes its activity against the invaded cancer cell.Bacteria are shown in green, liposomes in red and doxorubicin in orange.71