PDLLA (racemic polylactic acid) is an amorphous, bioresorbable polymer composed of randomly arranged repeating units of L-lactic acid and D-lactic acid. It exhibits good biocompatibility and biodegradability, readily degrading in vivo through hydrolysis and enzymatic degradation into lactic acid, and ultimately metabolized into carbon dioxide and water.
In the medical device field, PDLLA is frequently used as a coating material for drug-eluting stents to achieve controlled drug release. For example, in coronary intervention, a PDLLA coating can carry antiproliferative drugs (such as rapamycin) and be uniformly coated on the stent surface to help prevent restenosis. This coating effectively reduces complications such as late thrombosis, and the degradation process is synchronized with vascular repair.
The advantages of PDLLA coatings include good film-forming properties, a smooth surface, moderate mechanical properties, and suitability for stent surfaces with complex shapes. Through chemical modification (such as the introduction of carboxyl groups), PDLLA can be further functionalized to enhance its binding ability with drugs or other polymers and optimize drug release kinetics.
Application Areas
● Orthopedic Implants: PDLLA coating is applied to the surface of artificial bone screws and plates to facilitate slow degradation of the implant and gradual ingrowth into bone tissue, avoiding the need for secondary surgery.
● Vascular Interventional Devices: PDLLA drug-eluting coating is applied to the surface of coronary stents. Controlled degradation of the coating allows for sustained drug release, reducing the risk of in-stent restenosis.
● Tissue Engineering Scaffolds: PDLLA coating is applied to the surface of porous polymer scaffolds to regulate porosity and degradation rate, adapting to the repair needs of cartilage, skin, and other tissues.
Key Advantages of Shanghai Yangmi's Ultrasonic Spraying for PDLLA Coatings:
● High Coating Uniformity: The narrow droplet size distribution of ultrasonic atomization (1–50 μm) allows for coating thickness deviations within ±5% after deposition on medical device surfaces, making it particularly suitable for full-coverage coating of complex-shaped medical devices (such as porous stents and threaded implants).
● High Material Utilization: Compared to the 30%–50% material utilization rate of traditional air spraying, ultrasonic spraying achieves over 80% material utilization, significantly reducing PDLLA raw material costs and meeting the requirements of refined medical material production.
● Natural Coating, Protecting Material Performance: The atomization process is free from high-pressure airflow impact and requires no high-temperature assistance, avoiding thermal degradation or molecular chain breakage of PDLLA during preparation and ensuring the stability of the coating's biodegradation rate.
