Medical Stents Technology

Types and Coatings of Medical Stents | Function and Technical Principles of Stent Coatings

In minimally invasive treatment of cardiovascular, digestive, respiratory and other diseases, medical stents are indispensable core instruments. It is like a “micro support skeleton” that opens up the diseased lumen, relying on its small volume and good mechanical properties to open narrow or blocked human passages, saving a large number of patients. Many people have only heard of stent surgery, but do not understand the classification of medical stents and the key factor determining their long-term safety – surface coating technology.

According to material and degradation characteristics, medical stents are mainly divided into two categories: permanent metal stents and biodegradable stents. Permanent metal stents have the longest development time and are mostly made of medical alloys. They have excellent support and can be implanted into the human body for a long time, firmly maintaining the open state of blood vessels, airways and other lumens. They are a very mature category for clinical applications. However, the long-term presence of metal foreign objects in the body may induce chronic inflammation, restenosis, and other problems, prompting researchers to develop a new generation of products.

Degradable scaffolds have been a hot research and development topic in recent years, with substrates mainly composed of high molecular weight polymers or biodegradable metals. Its characteristic is that after completing the mission of supporting blood vessels, it can gradually decompose and absorb in the human body, ultimately no longer retaining foreign bodies, greatly reducing the long-term risk of foreign body related diseases, especially suitable for young patients. In addition to vascular stents, there are also hollow organ stents used in clinical practice for the esophagus, biliary tract, and trachea to relieve obstruction caused by tumors and stenosis. Different parts of the stent have been designed with targeted shapes, flexibility, and radial support.

The stent substrate is only the skeleton, and the surface coating is the core to control postoperative complications. The direct contact of bare stents with human tissue can easily cause excessive proliferation of vascular smooth muscle, leading to restenosis of the lumen. The appearance of coatings effectively solves this pain point. The most common is drug-eluting coatings, which load drugs that inhibit cell proliferation onto the coating matrix. After stent implantation, the drugs are slowly released, inhibiting intimal hyperplasia and significantly reducing the probability of restenosis.

In addition, there are various functional coatings available. Anticoagulant coatings can reduce platelet aggregation and lower the risk of thrombosis; Bioactive coatings can promote rapid growth of endothelial cells and accelerate endothelial repair; Antibacterial coatings are commonly used for gastrointestinal and airway stents to inhibit bacterial colonization and reduce the risk of infection. Coating is not just about brushing a thin film, it requires extremely high uniformity, thickness, and adhesion. Ultrasonic spraying can prepare thin and uniform drug coatings, effectively avoiding the risk of drug release caused by uneven coating thickness.

The research and development of medical stents has always been iterating towards safer and more user-friendly directions. Stronger support, more precise drug release control, and better biocompatibility are the future development goals. Behind the small bracket, multiple disciplines such as materials science, pharmacy, and precision manufacturing are integrated to continuously safeguard the smoothness of the human body’s cavity.

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