A nanofiber-based biodegradable millirobot, called Fibot, can move in the intestines and degrade in response to the pH of its environment, thus releasing different drugs in different anchored positions. The research has shown the potential application of millirobots for the controlled release of drugs in targeted positions in the intestines. The research has also facilitated the development of biodegradable and adaptive devices with biomedical applications.
Fibot’s legs can penetrate intestine mucosa, which enables it to anchor at the desired intestine position without being pushed away by peristalsis. This is a prerequisite for drug release at a targeted position. Also, with precise control of the magnetic field, Fibot’s legs do not reach the submucosa and muscularis externa layers of the gastrointestinal tract, thus effectively avoiding the potential risk of bowel perforation.
The team found that driven by magnetic force, Fibot moved 7 cm in 10 seconds in a pig’s stomach, which is rugged, wet, and acidic, with a pH of 5. This demonstrated Fibot’s locomotive ability in the stomach.
The team also conducted an in vivo experiment in a rabbit’s intestine with Fibot. When Fibot moved to the targeted intestinal region, the team applied a stronger magnetic field to anchor it to the intestinal tissue. Fibot stayed there for four hours and eventually was fully degraded in that position.