Shotgun on the tumor
Scientists from the California University of Technology are working on micro-robots that can deliver drugs to certain places inside the body.
Such micro-robots are designed to treat tumors of the digestive tract. They consist of microscopic magnesium spheres covered with thin layers of gold and parylene– a polymer resistant to the acidic environment of the stomach. Part of the sphere is uncovered and looks like a kind of porthole. It reacts with the fluids in the intestine, forming a stream of small bubbles that propel the sphere forward until it collides with nearby tissue. The drug is placed between a separate microsphere and its parylene layer. Then, to protect the micro-robots from the aggressive environment of the stomach, they are wrapped in microcapsules of paraffin wax. At this stage, the spheres can carry medicines, but are still not able to deliver them to the right place.
To solve this problem, photoacoustic computed tomography is used, a technique that uses pulses of infrared laser radiation. Infrared laser light is scattered through tissues and absorbed by oxygen-carrying hemoglobin molecules in red blood cells, causing the molecules to vibrate in the ultrasonic range. These ultrasonic vibrations are detected by sensors pressed against the skin. The indicators of these sensors are then used to create images of the internal structures of the body.
Tomography can be used to detect tumors and even individual cancer cells. Using this method, coupled with micro-robots, doctors will be able to detect tumors in the digestive tract, as well as track the location of micro-robots, because they are clearly visible on tomographic images. As soon as the micro-robots get into the tumor, they are activated using an infrared laser. Since micro-robots actively absorb infrared light, they heat up and melt the wax capsule, exposing themselves to digestive juice. At the same time, bubble jets are activated, and the micro-robots begin to move haphazardly, like inflated balloons with a released "needle", but remaining in a given area, and shoot the tumor as if from a shotgun.
Computer animation of the "shotgun" can be viewed here.
When they get into the mucous membrane of the digestive tract, they are fixed in it and can remain there for a long time.
Animal tests have shown that the micro-robots work as intended. Scientists plan to continue research and evaluate the therapeutic effect of this method. Scientists would also like to develop micro robots capable of working in other parts of the body. The problem is that infrared laser radiation hardly penetrates deep into the body.
Wu et. al's article A microrobotic system guided by photoacoustic computed tomography for targeted navigation in intestines in vivo is published in the journal Science Robotics.
Elena Panasyuk, portal "Eternal youth" http://vechnayamolodost.ru based on Caltech materials: Microrobots Activated by Laser Pulses Show Promise For Treating Tumors.