Zinc-based subcuticular absorbable staples: An in vivo and in vitro study

Area of Science:

• Biomaterials Science
• Materials Engineering
• Wound Healing Research

Background:

• Commercially available subcuticular absorbable staples (SAS) are typically made from poly(l-lactide-co-glycolide) (PLGA).
• There is a need for stronger, more robust alternatives for wound closure, especially in tissues with high mechanical loading or slow healing rates.

Purpose of the Study:

• To develop and characterize the first metallic subcuticular absorbable staples (SAS) using a zinc-nutrient element alloy (Zn-1.0Cu-0.5Ca).
• To compare the fixation properties, biodegradability, and biocompatibility of these novel zinc-based SAS against commercially available PLGA SAS.

Main Methods:

• Fabrication of zinc-based alloy staples (Zn-1.0Cu-0.5Ca).
• In vitro pull-out and lap-shear tests to evaluate fixation strength compared to PLGA staples.
• In vivo implantation in Sprague-Dawley (SD) rats to assess biodegradability, biocompatibility, and inflammatory responses over 12 weeks.

Main Results:

• Zinc-based SAS demonstrated significantly higher initial fixation force (18.9 N) compared to PLGA SAS (5.5 N).
• Uniform degradation of zinc SAS was observed in vivo, with average degradation rates of 198, 112, and 70 μm/y at 1, 4, and 12 weeks, respectively.
• Successful wound closure and healing were achieved with zinc SAS, comparable to PLGA staples, though higher stiffness led to increased foreign body responses.

Conclusions:

• Zinc-based SAS represent a promising metallic alternative for subcuticular wound closure, offering superior fixation strength for load-bearing applications.
• Further optimization, including reducing implant cross-section and applying corrosion-accelerating coatings, is suggested to improve long-term degradation and biocompatibility.
• The developed Zn-based SAS show potential for closing wounds in tissues requiring robust and sustained mechanical support during healing.