# Artificial Tendons’ Responsiveness to Mechanical Stress and Biological Performance Following Cork Extract Functionalization

## TL;DR

This study develops artificial hand tendons using polymer braids functionalized with cork extract, showing good mechanical and biological properties for tendon repair.

## Contribution

The novel use of cork extract to functionalize artificial tendons enhances their biological performance and mechanical suitability for hand tendon repair.

## Key findings

- Cork extract 2 showed high antioxidant and antimicrobial activity with low cytotoxicity.
- Functionalized braids demonstrated controlled release of cork extract and sustained bioactivity.
- Lyocell-based braids functionalized with cork extract exhibited the best overall performance.

## Abstract

Hand tendon ruptures have increased due to mechanical
stress, degeneration,
trauma, and repetitive motion. This study proposes an artificial tendon
engineered from polymeric braids made of lyocell, biodegradable polyester,
and polyethylene terephthalate, functionalized with natural cork extract.
Cork extract 2, obtained by cork powder using hydroethanolic solvent
in a planetary mixture, exhibited a phenolic content of 508.35 ±
82.26 mg GAE/g, flavonoid content of 607.32 ± 63.96 mg EQ/g,
strong antioxidant activity (EC50 = 0.21 ± 0.02 mg/mL),
and antimicrobial efficacy, with minimum bactericidal concentrations
of 0.16 mg/mL against Staphylococcus aureus and 0.64 mg/mL against Pseudomonas aeruginosa. Single-polymer braids were processed with a core–shell structure,
in which the core was formed of loose strands. The mechanical characterization
of the braids showed the three polymers to exhibit an elongation at
break of 8.72 ± 2.05–18.72 ± 6.58% and tensile strength
of 44.22 ± 12.02–53.15 ± 12.62 MPa, all within desirable
ranges for hand tendon repair/substitution. Braids were functionalized
via physical adsorption of cork extract 2 (1.60 mg/mL), achieving
loading values between 0.33 ± 0.16 and 0.55 ± 0.14 mg/mL.
The presence of extract in the braids was confirmed via infrared spectroscopy
and through thermal characterization, thermogravimetry, and differential
scanning calorimetry. Functionalized braids exhibited controlled release
of the cork extract 2, ranging from 1.57 ± 4.14 to 13.90 ±
2.02% within 24 h, ensuring sustained bioactivity, demonstrating as
well strong antioxidant activity (87.42 ± 1.18 reduced 2,2-diphenyl-1-picrylhydrazyl),
antimicrobial activity (achieving up to 99% reduction in S. aureus and 80% reduction in P.
aeruginosa), and low cytotoxicity (>70% metabolic
activity); with the functionalized lyocell presenting the best overall
performance. In general, the proposed strategy demonstrated promise
for hand tendon repair, offering a potential innovative solution to
improve patients’ quality of life.