Bioresorbable Yarns, Fibers, Tubing, & Films Overview:
Bioresorbable polymers (also referred to as bioabsorbable polymers, resorbable polymers, absorbable polymers, and degradable polymers) may be processed via melt extrusion into a variety of formats that include but are not limited to monofilament fibers, multi-filament yarns, tubing, and films. These extruded materials may be processed further into a final bioresorbable medical device or component that may be implanted in a patient for treatment and safely metabolized or excreted later when the implant is no longer required. In addition to typical mechanical requirements for fibers & yarns and dimensional requirements for tubing, extruded resorbable materials require careful material characterization including but not limited to molecular weight (often measured via inherent viscosity), residual monomer, identity testing, and moisture content. Melt extrusion requires a careful balance four (4) main process settings of 1) moisture management, 2) optimizing the polymer melt profile, 3) the appropriate mechanical shear imparted on the molten polymer, and 4) extrudate orientation in-line or off-line. Minimization of moisture ensures polymer degradation is lessened as water is a driving factor in the hydrolytic degradation of resorbable polyesters. Temperature deviations outside of the validated range of an extrusion process may result in generation of increased levels of residual monomer (elevated levels of residual monomer above certain thresholds are associated with cytotoxicity) and degradation of the polymer leading to a decrease average molecular weight (which has the potential to alter a materials degradation profile). A careful balance between mechanical shear and temperature ensures that residual monomer generation is abated while molecular weight of the polymer is maintained. Finally, in-line (or off-line) orientation allows proper sizing and strength setting for extrudate materials. By having well-controlled processes that balance these four (4) factors, extrudate materials can have optimal molecular weight, reduced monomer content, all while ensuring critical material properties of size, strength, and resorption profile are achieved. The section below outlines extrusion processing methods for bioresorbable materials currently available at Poly-Med.
Bioresorbable Monofilament Fibers:
Bioresorbable materials may be melt extruded into monofilaments consisting of a single strand of fiber where the diameter is greater than one-hundred (100) microns, or microfilaments consisting of a single strand of fiber with a diameter of less than one-hundred (100) microns.
Typically, monofilament fibers are oriented to enhance mechanical properties, dimensional stability, or flexibility. Monofilaments may be utilized as is in smaller diameters as suture materials or for FDM 3D printing in larger diameters. Overall, synthetic absorbable fiber sutures exhibit a smaller diameter than naturally-derived collagen sutures to meet strength requirements as shown in Table 1. Of note, absorbable suture diameters typically remain on the high end of USP size ranges to meet the strength requirements as compared to their non-absorbable suture counterparts.
|Collagen Sutures||Synthetic Sutures|
|USP Size||Metric Size||Diameter Range (mm)||Metric Size||Diameter Range (mm)|
|7||–||–||9||0.900 – 0.999|
|6||–||–||8||0.800 – 0.899|
|5||–||–||7||0.700 – 0.799|
|4||8||0.800 – 0.899||6||0.600 – 0.699|
|3||7||0.700 – 0.799||6||0.600 – 0.699|
|2||6||0.600 – 0.699||5||0.500 – 0.599|
|1||5||0.500 – 0.599||4||0.400 – 0.499|
|0||4||0.400 – 0.499||3.5||0.350 – 0.399|
|2-0||3.5||0.350 – 0.399||3||0.300 – 0.339|
|3-0||3||0.300 – 0.339||2||0.200 – 0.249|
|4-0||2||0.200 – 0.249||1.5||0.150 – 0.199|
|5-0||1.5||0.150 – 0.199||1||0.100 – 0.149|
|6-0||1||0.100 – 0.149||0.7||0.070 – 0.099|
|7-0||0.7||0.070 – 0.099||0.5||0.050 – 0.069|
|8-0||0.5||0.050 – 0.069||0.4||0.040 – 0.049|
|9-0||0.4||0.040 – 0.049||0.3||0.030 – 0.039|
|10-0||–||–||0.2||0.020 – 0.029|
Bioresorbable monofilament fibers may also be processed into biomedical textiles for use in mesh & graft implants or braided into hollow tube structures. Poly-Med offers both custom extrusion of our portfolio of bioresorbable polymers and off-the-shelf monofilament fibers that may be used in downstream processing:
|Material||USP Class||Diameter (mm)||Peak Load (N)||Elongation|
|Max-Prene® 955||6-0||0.075 – 0.090||>4||15 – 30%|
|Glycoprene® 935||5-0 and 6-0||0.095 – 0.115||>5||20 – 40%|
|Glycoprene® 7424 + BaSO4||3-0 and 4-0||0.250 – 0.310||≥13||20 – 50%|
Bioresorbable Multifilament Yarns:
Bioresorbable materials can be melt extruded into yarns made of multiple strands of filaments ranging from 1.5 – 30 denier per filament and 5 – 80 filaments per bundle. Multifilament fibers are oriented in-line and are known to be utilized as components in biomedical textiles for use in mesh & graft fabrics or braided into suture materials for tissue closure. Poly-Med offers both custom extrusion of our portfolio of bioresorbable polymers and off-the-shelf multifilament yarns that may be used in downstream processing:
|Material||Filament Count||Denier (g/9000m)||Tenacity (gf/denier)||Elongation|
|Glycoprene® 935||10||180 – 200||≥3.0||>30%|
|Glycoprene® 935||20||70 – 100||>2.5||40 – 80%|
|Lactoprene® 8411||25||80 – 100||>3.0||20 – 40%|
|Lactoprene® 8812||86||160 – 180||≥3.0||20 – 40%|
Bioresorbable materials may be melt extruded into hollow tubing materials exhibiting a range of inner and diameter measurements based on the medical device dimensional requirements. Poly-Med has the ability to extrude bioresorbable tubing with outer diameters ranging from 0.9 – 8.0 mm and may be further processed into formats applicable to a particular bioresorbable medical device such as stents or material carriers. Poly-Med offers custom extrusion of our portfolio of bioresorbable polymers for development and manufacturing of bioresorbable tubing. Poly-Med also offers custom profiled extrudates where unique geometries can be created to provide additional form factors for tubing design.
Bioresorbable materials may also be melt extruded into film formats exhibiting a range of thicknesses and width measurements based on the device dimensional requirements. Poly-Med has the ability to extrude bioresorbable films with thicknesses ranging from seventy (70) to three hundred (300) microns and widths up to 12.7 centimeters. Bioresorbable films may be used as components requiring a degradable layer or as final devices for direct contact with non-structural tissue indications. Poly-Med offers custom extrusion of our portfolio of bioresorbable polymers for development and manufacturing of bioresorbable films.
Extrusions of Bioresorbable Polymers with a Vertically Integrated Partner:
Manufacturing bioabsorbable extruded materials is challenging and requires know-how & expert process knowledge to deliver a consistent quality output. Controlling moisture levels and material degradation through the production cycle requires specialized equipment and process controls to ensure quality of finished devices. In contrast to other extrusion contract manufacturers that produce bioresorbable filaments, yarns, tubing, and films, Poly-Med produces bioresorbable polymers in-house, and extrudes this material into desired formats. Poly-Med is also able to warp or weft knit bioresorbable fibers and yarns to produce implantable biomedical textiles if downstream processing is required. In addition to accessing Poly-Med’s almost thirty (30) years of experience with bioresorbable polymer materials, partnering with Poly-Med simplifies your bioresorbable medical device manufacturing supply chain. Contact us to today begin developing your next bioresorbable extruded monofilament fiber, multifilament yarn, tubing, or film with a trusted partner for manufacturing advanced bioresorbable medical devices!