Zinc-Based Subcuticular Absorbable Staples: An In Vivo and In Vitro Study

Abstract

A zinc-nutrient element alloy (Zn-1.0Cu-0.5Ca) was developed into subcuticular absorbable staples (SAS) as a robust alternative to the commercially available poly(l-lactide-co-glycolide) (PLGA) SAS for the first time. The fixation properties of the Zn SAS were measured via pull-out tests and in-situ lap-shear pull-out test comparatively against the PLGA SAS. The Zn SAS exhibited fixation force of 18.9±0.2 N, which was over three times higher than that of PLGA SAS (5.5±0.1 N). The Zn SAS was used to close incision wounds in a SD rat model for biodegradability and biocompatibility characterisation at 1, 4 and 12 weeks. The Zn SAS showed uniform degradation behaviour after in vivo implantation at the average rate of 0.198±0.054, 0.112±0.028, and 0.070±0.026 mm/y after 1, 4, and 12 weeks, which reduced the fixation force to 16.80±1.14 N, 15.4±0.85 N, 12.73±0.69 N, respectively. These findings showed the potential of the Zn SAS for the closure of heavy loading and slowing healing tissues. The Zn SAS enabled successful closure and healing of the incision wound, similar to the PLGA staples. However, the slow long-term degradation rate of the Zn SAS may lead to unnecessary implant retention. In addition, the alloy SAS resulted in higher local foreign body responses due to their stiffness. Reducing the implant cross-section profile and applying low stiffness and a corrosion-accelerating coating are suggested as possible approaches to reduce post-service implant retention and improve the biocompatibility of the Zn SAS.

Note:
Funding Information: N. Yang, J. Venezuela, R. Allavena and M. Dargusch acknowledge the support of the Australian Research Council through the ARC Research Hub for Advanced Manufacturing of Medical Devices (IH150100024).

Declaration of Interests: The authors declare no conflict of interest.

Ethics Approval Statement: All procedures conform to the requirements of the University of Queensland (UQ) Animal Ethics Committee (Approval number: 2021/AE000935), the Animal Care and Protection Act Qld, and the Australian Code of Practice for the Care and Use of Animals for Scientific Purposes.

Keywords: absorbable subcuticular staple, wound closure, Zn alloy, biodegradability, biomechanical properties, in vivo implantation