Bordering on science fiction, medicinal microrobots could help physicians better treat and prevent diseases. But a serious problem is the synthetic materials they are made of trigger immune responses. Now, for the first time, researchers report in ACS Central Science that they achieved precise control neutrophils as a natural, biocompatible microrobot by using lasers. By getting the ‘neutrobots’ to perform multiple tasks, the researchers demonstrated they could one day deliver drugs to precise locations in the body.
Microrobots being developed for medical applications would need to be administered in injections or oral capsules to get them inside the body. But these microscopic objects are often found to trigger immune reactions in small animals, resulting in the the microrobots being ejected from the body before they can carry out their tasks. By using the body’s own cells, such as neutrophils, drugs could be delivered less invasively without provoking an immune response.
Neutrophils already naturally pick up nanoparticles and dead red blood cells and can migrate through blood vessels into adjacent tissues, so they are good candidates for becoming microrobots. Previously, researchers have guided neutrophils with lasers in lab dishes, moving them around as ‘neutrobots’. However, this had not been tried in living animals. So, researchers set out to demonstrate the feasibility of light-driven neutrobots in animals using live zebrafish.
The researchers manipulated and moved neutrophils in zebrafish tails, using focused laser beams as optical tweezers. The ‘neutrobots’ could be moved up to a velocity of 1.3 µm/s, three times faster than a neutrophil’s natural speed. The optical tweezers were able to precisely and actively control the functions that neutrophils conduct as part of the immune system. For example, moving through a blood vessel wall into the surrounding tissue; carrying a plastic nanoparticle, showing potential for delivering medicine; and pushed towards red blood cell debris, a neutrophil engulfed the pieces. Surprisingly, at the same time, a different neutrophil, which wasn’t controlled by a laser, tried to naturally remove the cellular debris. Because they successfully controlled neutrobots in vivo, the researchers say this study advances the possibilities for targeted drug delivery and precise treatment of diseases.
Source: American Chemical Society
