New catheter inspired by blood vessels could become game changer

Inspired by blood vessels themselves, researchers in China have created a new "bio-inspired" liquid gating membrane-based catheter out of novel materials that mimic the function and purpose of the vascular system. The catheter could be a game changer in the use, safety and versatility of catheters and other derived applications.  

The results of the research were published Sept. 4 in Science Advances, written by Chunyan Wang, Shuli Wang, Hong Pan, Lingli Min, Huili Zheng and others.

Modeled after veins, catheters are mainly used to drain the bladder of urine but can also be used to drain other fluids elsewhere in the body, and administer intravenous fluids and drugs. They can also be used to insert surgical devices. The vein, or hose, of the catheter that is inserted into the body is typically made with vinyl, rubber or latex or silicone. 

Although highly useful and life-saving, modern catheters still have problems. 

Thrombosis, or blood clots can still occur with current designs, meaning it's important to select the right size tube for various vein lumens. Different sizes can mitigate coagulation but won't completely stop blood from clotting. They are also unadaptable to environmental changes and have single functionality.  

Anticoagulation properties and lumen size adaptability are necessary for effective catheters. To mitigate blood clots and infection, as well as constructing a more efficient delivery system for drugs, researchers took inspiration from the flexibility and "specific mass transfer pathways" of blood vessels. 

The liquid-infused gating membrane catheter (LGMC) uses liquids that have gating functions (think 'gate') as building material. The "membrane takes advantage of the unique ability of a fluid to deform and reconfigure in situ to respond to capillary pressure," the published research showed, instead of relying on molecular switches, external gates, or changing the physical geometry of catheter materials. The functionality of the liquid gate is increased by using (membrane) material that has a wide range of innate responses to different liquids, is adaptable to different environmental pressures, and highly resistant to contamination – "virtually no fouling for complex fluids."

An LGMC tube that enters the body behaves more like blood vessels than a traditional tube.. 

The microporous membrane is constructed using the electrospinning method – a method of producing fiber that involves electricity. Pore size in the membrane is "selected and controlled by different electrospinning parameters": the concentration of the solution used as building material and the voltage, the Science Advances article states. Time duration of the electrospinning process doesn't affect the pore size of the membranes but does affect the thickness of the membrane, which may have other applications.

The details of the LGMC's construction are somewhat esoteric, but suffice to say that fabricators "[used] a continuous fluid layer," like endothelium in blood vessels, to endow it with tube size adaptivity, anticoagulation and improve the drug release function. The material is also highly biocompatible.

"In addition, owing to the inherent dynamic property of the gating liquid, LGMC is supposed to naturally restore itself when facing physical damage through molecular turnover and local flow," the report noted. 

This research shows that the LGMC technology is viable. Liquid membrane catheters could potentially "spark further experimental and theoretical efforts with the choice of different functional matrices and gating liquids for the exploitation of more complex catheter applications." 

Prospective technologies like 3D printing and "pore-forming agent–based fabrication," could be used with different materials.

Although there is room for improvements, and the LGMC is still in an early form, researchers believe that this technology is a step in the right direction in terms of creating a safer, more functional and better-performing "smart catheter."