Project name:              Solution spun PLA fibers with pH-neutral degradation characteristics


Fourné Maschinenbau GmbH

ITA – Institute for Textile Technology for RWTH Aachen

AME – Helmholtz Institute for Biomedical Engineering

DWI – Leibniz Institute for interactive Materials

EnvisionTec GmbH

Duration:                      03/2017 – 02/2020

Funding authority:       European Regional Development Fund North Rhine-Westphalia (EFRE.NRW)

Biodegradable materials have found a wide-ranging application in medicine today (sutures, wound dressing, implants and many more). Nevertheless, the most commonly used biomaterials, such as PGA, PLA, etc., degrade with an acute release of acidic valences. The acids released lead to local acidosis (hyperacidity) with sometimes dramatic clinical consequences, such as massive inflammatory reactions up to complete tissue destruction.

The aim of the project is therefore (1) to develop new biodegradable materials with optimized pH degradability and (2) to enable their processability as (2a) textile medical devices, and as (2b) complex patient-individualized implants by means of rapid prototyping.

The pH-optimized degradation is to be achieved by a material system of conventional biodegradable biomaterials (PLA) and μ-gels with high proton binding capacity. Accordingly, the acidic valences released during degradation are intercepted before they become clinically relevant.

In preliminary investigations, a clear superiority of μ-gel-additivated fibers could already be proven in the pH behavior compared to conventional fibers as well as conventional buffer systems. The inhomogeneous, randomized distribution of the μ-gels in the fiber, however, has led to considerable problems in the (re-) producibility of the fibers and their constant mechanical properties.

The approach chosen in the project is therefore to enable the additivation of μ-gels in a defined geometrical arrangement. On the (i) fiber side, this is achieved by the production of defined fiber cross-sections using bicomponent solvent spinning processes (e.g. core-skin or segmented fiber), while for (ii) patient-individualized production using rapid prototyping, a targeted storage of µ-gel depots can be achieved. In spinning trials the spinning technology (dry/wet/ airgap spinning), the spinning solution, process parameters and nozzle geometry will be systematically varied. Subsequently fibres will be evaluated by degradation studies, microscopy and tensile testing. The chair of Biohybrid and Medical Textiles of the RWTH Aachen is conducting the development of the bicomponent solvent spinning process in cooperation with Fourné Maschinenbau GmbH. The new materials are then chemically, mechanically and biologically characterized for their usability in medical applications.

The pHMed consortium is made up of an ideal combination of academic and industrial partners, which can quickly translate the results into industrial applications after project completion. With Evonik Creavis as a global NRW company, one of the largest manufacturers of biodegradable materials (Resomer® product family) is available for the upscaling of processes.

For the production of a fiber in the bicomponent solution spinning process, the bicomponent spin pack, its construction up to the spinneret and the local arrangement in the coagulation part of the solution spinning system is of essential importance for the production of a defined and reproducible bicomponent yarn cross-section.

A defined and reproducible bicomponent yarn cross-section not only permits uniform further processing, but is also the basis for constant stress-strain behaviour over the entire yarn production time.  These bicomponent yarn properties are essential to produce a high-quality fiber of consistent quality suitable for medical applications.

With the development of a bicomponent spin pack for the solution spinning process, an important basis for the production of a high-quality medical bicomponent fiber is thus created.


The Project “pHMed” (EFRE-0800639) is supported by the European Regional Development Fund North Rhine-Westphalia (EFRE.NRW).