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Nanoscale Cell-Like Robots Shown to Clean Blood

Coated nanorobots

Scanning electron microscope image of nanorobots with hybrid blood cell membrane coating (courtesy Esteban-Fernández de Ávila and Science Robotics)

1 June 2018. Engineering researchers developed tiny robotic devices, powered by ultrasound and designed to look and act like blood cells, which in lab tests cleared human blood of dangerous bacteria and toxins. A team from University of California in San Diego describes the devices and test results in the 30 May issue of the journal Science Robotics (paid subscription required).

Researchers from the labs of nanoengineering professor Joseph Wang and nano/bioengineering professor Liangfang Zhang are collaborating on this project to develop systems able to work inside the body for decontaminating bodily fluids. Both research groups deal with nanoscale devices, where 1 nanometer equals 1 billionth of a meter. Wang’s lab studies the fabrication and operation of nanoscale devices, while Zhang’s group focuses on nanoscale delivery of drugs and vaccines.

To move devices this small, the team chose to power the robots externally, using ultrasound waves, with the core of the devices made of gold nanoscale wires, which respond to ultrasound. The researchers created a a hybrid of outer membranes from red blood cells and blood platelets with high-frequency sound waves, then coated the nanowires with this biomaterial using electrodeposition. These membrane materials were chosen not only for the devices to look like cells, but also interact like cells with their targets. Platelets bind to microbes in blood, including antibiotic resistant Staphylococcus bacteria, while red blood cells absorb the toxins produced by these bacteria. The hybrid membrane surface, say the authors, also discourages proteins from collecting and fouling the devices.

“The idea is to create multifunctional nanorobots that can perform as many different tasks at once,” says postdoctoral researcher and first author Berta Esteban-Fernández de Ávila in a university statement. “Combining platelet and red blood cell membranes into each nanorobot coating is synergistic. Platelets target bacteria, while red blood cells target and neutralize the toxins those bacteria produce.” In September 2015, Science & Enterprise reported on Zhang and colleagues developing nanoparticles disguised as blood platelets for therapies.

Tests of the devices in blood samples show the devices, responding to ultrasound waves, can travel up to 35 micrometers per second; 1 micrometer, or micron equals 1 millionth of a meter. In other tests, the team mixed methicillin-resistant Staphylococcus aureus, or MRSA, bacteria into the blood samples, as well as the pore-forming toxins they produce. MRSA bacteria are a continuing public health threat, responsible for a number of infections, including in hospitals and clinics. After 5 minutes of ultrasound exposure, blood with the nanorobots reduced blood cell damage by 40 percent, compared to 17 percent for the devices placed in blood without ultrasound, as well as lowering the volume of bacteria and toxins.

The researchers plan to continue developing the nanorobots beyond this proof-of-concept device. A key step is finding a more biocompatible material than gold for the core of the device, which will enable tests of the nanorobots on live animals. Esteban-Fernández de Ávila and Wang tell more about the devices in the following video.

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