Biodegradable AZ91 magnesium alloy/sirolimus/poly D, L-lactic-co-glycolic acid-based substrate for cardiovascular...

Area of Science:

• Biomaterials Science
• Cardiovascular Engineering
• Drug Delivery Systems

Background:

• Biodegradable drug-eluting stents (DESs) are crucial for drug delivery to target sites.
• Magnesium (Mg) alloys offer potential for biodegradable cardiovascular stents.
• Limited research exists on biodegradable Mg alloys for cardiovascular stent applications.

Purpose of the Study:

• To develop a sirolimus-loaded poly D, L-lactic-co-glycolic acid (PLGA)-coated AZ91 Mg alloy-based substrate for cardiovascular stent application.
• To investigate the physicochemical, electrochemical, and in-vitro biological characteristics of the developed substrate.

Main Methods:

• AZ91 Mg alloy prepared via squeeze casting and alkali-treated for macroporous networks.
• Layer-by-layer coating with sirolimus and PLGA.
• Characterization using X-ray diffraction (XRD), contact angle measurement, electrochemical tests, and in-vitro biological assays.

Main Results:

• Alkali treatment increased substrate hydrophilicity and enhanced antibacterial properties.
• Sirolimus-loaded PLGA-coated Mg alloy (Mg/Na/S/P) exhibited improved anti-corrosion compared to bare Mg.
• Mg/Na/S/P substrate demonstrated a 70% antithrombotic effect and significant inhibition of valvular interstitial cell growth in vitro.

Conclusions:

• The developed sirolimus-loaded PLGA-coated AZ91 Mg alloy substrate shows controlled dissolution rates and favorable biological characteristics.
• The star-shaped structure of sirolimus/PLGA ensures drug bioavailability with release kinetics fitting the Higuchi model and zero-order mechanism.
• This Mg alloy-based substrate is a potential candidate for future cardiovascular stent applications.