Next Generation Bioresorbable Materials for 3D Printing Implantable Medical Devices

3D Printing Approaches Overview:

3D printing (additive manufacturing) processes produce three-dimensional parts through addition of material in a layer by layer fashion. Resorbable materials may be 3D printed using a variety of approaches including fused filament fabrication (FFF), selective laser sintering (SLS), and resin-based methods such as stereolithography (SLA) and dynamic light processing (DLP).

FFF produces parts by melting a continuous thermoplastic filament via extrusion through a heated printer head. Although the most widely utilized 3D printing technology, FFF also exhibits the lowest resolution with most printers requiring minimum layers heights ~100 microns and maximum XY resolution ~250 microns. SLS creates parts by sintering powdered materials with a laser to near-melting temperatures which causes the powder particles to fuse together to form a solid structure. SLS exhibits medium printing resolution most printers requiring minimum layer heights ~60 microns and maximum XY resolution ~80 microns. SLA produces parts through a photopolymerization process where a UV laser is focused on a photopolymer vat. SLA exhibits the highest resolution of the described methods with a minimum layer height ~50 microns and maximum XY resolution ~50 microns. Bioresorbable 3D printing materials are available for FFF, SLS, and more recently SLA-based printing methods.

3D Printing Unlocks New Design Architectures for Tissue Scaffolds:

Traditional injection molded parts are limited to solid infill designs due to the requirement resin flowing throughout a mold. In contrast, 3D printing allows for complex infill geometries such as the gyroid and honeycomb patterns to alter both the mechanical properties and cellular infiltration into the device based on its intended use. Additionally, utilization of bioresorbable materials allows for the device to maintain mechanical strength while it is needed, and to degrade into constituents that may be metabolized or excreted once the healing process has sufficiently progressed.

Figure 1A-F: A catalog of infill patterns are accessible via 3D printing that are not accessible via traditional injection molding approaches. These patterns include but are not limited to A) line, B) gyroid, C) octlet, D) concentric, E) tri-hexagon, and F) grid infill designs (Images from Xometry.com).

FFF 3D Printing versus Micro Injection Molding Bioresorbable Devices:

Micro-injection molding is a manufacturing process capable of producing parts between 0.1- 1 gram with tolerances ranging from 10-100 μm. As with traditional injection molding, design changes to the part mold may be prohibitively expensive with each mold costing ~$10,000 for low-volume/simple molds and up to $100,000 to high volume molds. Given the high barrier to entrance into injection molding, PMI’s FFF filament line of materials offers biomedical engineers the ability to iteratively test bioresorbable medical devices designs quickly and cost effectively. Additionally, PMI’s FFF filament materials are offered in standard 1.75 mm formats that are compatible with most open source FFF printers. For volumes applicable to many implantable medical devices, FFF printing is an economical alternative to injection that opens new design features to be imparted better suited for bioabsorbable implants.

Figure 2A-F: Poly-Med offers a catalog of off-the-shelf bioabsorbable filaments for FFF 3D printing. Available materials include A) Max-Prene® 955, B) Dioxaprene® 100M, C) Lactoprene® 100M, D) Strataprene® 5525, and Caproprene® 100M, as well as custom material extrusions.

Poly-Med’s now offers Photoset® Resin for Photo-Polymerization 3D Printing Methods:

Poly-Med’s team of material scientists have developed first-in-class bioresorbable fast-degrading resins for photopolymerization 3D printing methods that include SLA, DLP, and two (2) photon polymerization. In contrast to the limited bioresorbable 3D printing resins currently available, Poly-Med’s Photoset® resin product line utilizes monomeric constituents that have used in medical devices for over forty (40) years and are anticipated to be biocompatible with the data collected to date. Additionally, Poly-Med’s material scientists can tune the Photoset® resin mechanical properties and degradation timeline to best meet a device’s requirements. 3D printing with Poly-Med’s Photoset® resin allows for unparalleled resolution when manufacturing bioresorbable medical implants that require small design features.

Figure 3: Examples of model parts printed with Poly-Med’s Photoset® bioabsorbable resin. The Photoset® resin formulation may be customized to the mechanical requirements and degradation profile necessary for a particular implantable medical device.

Poly-Med’s 3D Printing Services:

In addition to supplying materials, Poly-Med also offers design engineering and 3D printing services for parts made of FFF and SLA materials. Whether a design is not in its final iteration and consultation is needed or if a part design has been finalized and prototypes are needed for testing, Poly-Med’s design engineering is available to provide requested services.

As the leader in bioresorbable medical device manufacturing, Poly-Med offers development services for 3D printing, electrospinning, extrusion, and textiles in a certified ISO Class 8 cleanroom. Poly-Med facilities are certified to meet ISO: 13485:2016 standards for quality management of its design, development, and manufacturing of bioresorbable polymers, fibers, sutures, medical textiles, and biomedical products. Connect with Poly-Med today to learn more about 3D printing your next generation bioresorbable device by contacting sales@poly-med.com!

Bioresorbable Medical Devices as Implantable & Degradable Tissue Scaffolds

Bioresorbable Medical Device Overview:

Bioresorbable medical devices are implantable materials designed for a particular treatment and degrade over time once the scaffold is no longer necessary. Bioresorbable polymer materials may be synthetic or naturally-derived, exhibit high biocompatibility, and may degrade through mechanisms including but not limited to bulk hydrolysis, surface erosion, or enzymatic degradation depending on the material. Typically, degradable medical devices are produced with off-the-shelf traditional homopolymers or random co-polymers such polyglycolide (PGA), polylactide acid (PLA), polydioxanone (PDO), polycaprolactone (PCL), poly(lactide-co-glycolide) (PLGA), or poly(L-lactide-co-ε-caprolactone) (PLCL). Although readily available from multiple bioresorbable polymer suppliers, often these materials lack ideal characteristics for implantable medical devices due to their mechanical properties or degradation profiles for intended applications. In addition to manufacturing bioresorbable polymers in-house, Poly-Med can also transform off-the-shelf polymers and co-polymers, as well as our high-performance polymers through several manufacturing processes including but not limited to extrusion, braiding, knitting, electrospinning, and 3D printing. Poly-Med has extensive experience working with injection molding vendors that have successfully used our performance bioresorbable polymer resins.

Figure 1: Poly-Med offers a catalog bioresorbable polymers with different architectures, mechanical properties, and degradation profiles that may be selected based on a specific bioresorbable medical device application. A) Off-the-shelf bioresorbable polymers are typically homopolymers or random co-polymers that have non-segmented degradation profiles, such as Poly-Med’s Max-Prene® 955 PGLA co-polymer (95% glycolide / 5% lactide) and Dioxaprene® 100M polydioxanone homopolymer. B) Poly-Med’s Glycoprene® and Strataprene® polymer series exhibit polyaxial architectures and segmented degradation profiles. Here, flexible trimethylene carbonate (TMC) substituents are located within the polymer core and rigid glycolide/lactide constituents are located within the arms of the polymer creating a triadic design. C) Poly-Med’s Lactoprene® polymer series exhibit linear block co-polymer architectures with segmented degradation.

Bioresorbable Fibers, Yarns, Tubing, & Films:

Bioresorbable polymer materials may be extruded into a variety of formats that include but are not limited to fibers, yarns, tubing and films. 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 three (3) main process settings of 1) moisture management, 2) optimizing the polymer melt profile, and 3) the appropriate mechanical shear. Bioresorbable monofilament fibers are commonly used for in mesh & graft implants or braided into hollow tube structures, whereas multifilament yarns are commonly used in braided suture materials in addition to mesh & graft implants. Bioresorbable tubing has been used as a base material for larger diameter stent devices and for smaller diameter material carriers. These extruded bioresorbable polymer-based materials may be utilized at Poly-Med for downstream biomedical textile manufacturing within our vertically integrated supply chain or may handed off to an additional partner for processing outside of Poly-Med’s core service offerings.

Bioresorbable Biomedical Textiles:

Biomedical textiles are fiber-based medical devices that can be implanted in patients to restore tissue properties, provide mechanical support, as well as facilitate the healing process for a variety of indications. Textile-based implantable medical devices include but are not limited to sutures, meshes, vascular grafts, and heart valves. Although not melt-based processes, care still must be taken to limit moisture exposure of bioresorbable materials through the general production cycle as well as through heat setting of fabric materials. Poly-Med offers custom warp & weft knitting, and braiding for fiber-based textile applications as well as electrospinning for manufacturing non-woven fabric that may utilized as tissue scaffolds or wound matrices. These biomedical textiles may used as components for a final implantable medical device or as components in more complex constructs.

Bioresorbable 3D Printed Implants:

3D printing (additive manufacturing) processes produce three-dimensional parts through addition of material layer by layer. 3D printing technologies relevant to the bioresorbable polymer market include fused deposition modeling (FDM), selective laser sintering (SLS), and resin-based methods such as stereolithography (SLA) & dynamic light processing (DLP). FDM produces parts by melting a continuous thermoplastic filament via extrusion through a heated printer head, whereas SLA produces parts in a layer-by-layer fashion through a photopolymerization process where a UV laser is focused on a photopolymer vat. Poly-Med offers off-the-shelf 1.75 mm monofilament FDM filaments in fifty (50) grams quantities for developing your next prototype at your facility, in addition to offering design consulting and manufacturing services for 3D printing at Poly-Med’s facilities. Recently, Poly-Med has launched our first-in-class short-acting Photoset® bioresorbable resin for SLA and DLP printing applications. Our Photoset® resin can be customized to meet most mechanical and degradation design requirements for your next bioresorbable medical device implant. Poly-Med also offers design consulting and manufacturing services for developing Photoset® resin-based medical devices.

Figure 2: Poly-Med offers a catalog of manufacturing approaches for processing bioresorbable polymers that meet a variety of implantable medical device design requirements. Poly-Med can package these bioresorbable components or devices in simple and more complex arrangements that may include final device labeling to be utilized at healthcare providers.

Bioresorbable Injection Molded Implants:

Injection molding is a common approach for manufacturing bioresorbable medical devices as this technique is often the most cost-effective for solid devices to be sold in large volumes. Poly-Med’s bioresorbable polymer catalog may be processed via injection molding, although Poly-Med does not currently offer these services in-house. Poly-Med has extensive experience working with injection molding vendors that possess the ability to process bioresorbable materials into high-quality parts while maintaining material integrity. Our team would be happy to provide recommended vendors for processing our high-performance bioresorbable Glycoprene®, Strataprene®, and Lactoprene® polymer series.

Bioresorbable Medical Device Product Development with a Vertically Integrated Partner:

Manufacturing bioabsorbable medical devices is hard. 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 contract manufacturers that produce advanced bioresorbable materials, Poly-Med produces polymer, extrudes this material to desired monofilament or multifilament formats, and is able process this material via warp knitting, weft knitting, or braiding processes to produce a custom biomedical textile. Additionally, we can process our bioresorbable polymers into non-woven formats through electrospinning via our state-of-the-art electrospinning facility or 3D print your next prototype & finished bioresorbable medical device. 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. Of note, Poly-Med facilities are certified to meet ISO: 13485:2016 standards for quality management of its design, development, and manufacturing of bioresorbable polymers, fibers, sutures, medical textiles, and biomedical products. Contact us to today to begin developing your next generation absorbable product line with a trusted partner for manufacturing advanced bioresorbable medical devices!

Bioresorbable Polymer Extrusions of Yarns, Fibers, Tubing, & Films for Implantable Medical Devices

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.

Figure 1: Poly-Med offers a range of extruded bioresorbable materials that include A) monofilament fibers, B) multifilament yarns, C) hollow tubes, and D) panels of film material.

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 SizeMetric SizeDiameter Range (mm)Metric SizeDiameter Range (mm)
790.900 – 0.999
680.800 – 0.899
570.700 – 0.799
480.800 – 0.89960.600 – 0.699
370.700 – 0.79960.600 – 0.699
260.600 – 0.69950.500 – 0.599
150.500 – 0.59940.400 – 0.499
040.400 – 0.4993.50.350 – 0.399
2-03.50.350 – 0.39930.300 – 0.339
3-030.300 – 0.33920.200 – 0.249
4-020.200 – 0.2491.50.150 – 0.199
5-01.50.150 – 0.19910.100 – 0.149
6-010.100 – 0.1490.70.070 – 0.099
7-00.70.070 – 0.0990.50.050 – 0.069
8-00.50.050 – 0.0690.40.040 – 0.049
9-00.40.040 – 0.0490.30.030 – 0.039
10-00.20.020 – 0.029
Table 1: USP suture size and diameter specifications for collagen and synthetic absorbable sutures.

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:

MaterialUSP ClassDiameter (mm)Peak Load (N)Elongation
Max-Prene® 9556-00.075 – 0.090>415 – 30%
Glycoprene® 9355-0 and 6-00.095 – 0.115>520 – 40%
Glycoprene® 7424 + BaSO43-0 and 4-00.250 – 0.310≥1320 – 50%
Dioxaprene® 100M5-00.100– 0.140>530 – 50%
Table 2: Poly-Med offers a catalog of off-the-shelf monofilament fibers that may be used in downstream biomedical textile development.

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:

MaterialFilament CountDenier (g/9000m)Tenacity (gf/denier)Elongation
Glycoprene® 93510180 – 200≥3.0>30%
Glycoprene® 9352070 – 100>2.540 – 80%
Lactoprene® 84112580 – 100>3.020 – 40%
Lactoprene® 881286160 – 180≥3.020 – 40%
Table 3: Poly-Med offers a catalog of off-the-shelf multifilament yarns that may be used in downstream biomedical textile development.

Bioresorbable Tubing:

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 Films:

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!

Bioresorbable Polymers for Implantable Medical Devices

Bioresorbable Polymers Overview:

Bioresorbable polymers (also referred to bioabsorbable polymers, resorbable polymers, absorbable polymers, and degradable polymers) are synthetic or naturally-derived materials exhibiting high-biocompatibility and degrade into smaller molecules that may be safely excreted from a patient. Bioresorbable polymers may degrade through mechanisms including but not limited to bulk hydrolysis, surface erosion, or enzymatic degradation depending on the material. Typically, degradable medical devices are produced with off-the-shelf traditional homo-polymers or random co-polymers such polyglycolic acid (PGA), polylactic acid (PLA), polydioxanone (PDO), polycaprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA), , or poly(L-lactide-co-ε-caprolactone) (PLCL). Although readily available from multiple bioresorbable polymer suppliers, often these materials lack ideal characteristics for implantable medical devices due to their mechanical properties or degradation profiles for intended applications (Figure 1).

Figure 1: Most off-the-shelf resorbable co-polymers display random arrangement of monomers based on their input monomer ratios.

Poly-Med’s Advanced Bioresorbable Polymers:

Poly-Med offers off-the-shelf high-performance bioresorbable polymers suitable for any intended absorbable medical device application. Typically, these materials are more flexible and exhibit decreased crystallinity compared to more commonly used homo- or co-polymers in use. The section below outlines the advantages to selecting one of Poly-Med’s high-performance bioresorbable polymers over homo-polymers or random co-polymers.

Glycoprene® Polymer Series as an alternative to PGA and PGLA polymers:

PGA and PGLA polymers may exhibit tensile strengths in the GPa range and degradation profiles of strength loss within one (1) to six (6) weeks and mass loss within two (2) to four (4) months. Poly-Med’s Glycoprene® bioresorbable polymer series are polyaxial, segmented co-polymer formulations with varying ratios of glycolide, ε-caprolactone, and trimethylene carbonate (TMC) monomers (Figure 2). With this polymer architecture, TMC acts as a central flexible region that can then be end-grafted with varying ratios of glycolide and ε-caprolactone, creating a triadic structure. Poly-Med’s stiffer Glycoprene® 935 has a composition of 93% glycolide, 5% ε-caprolactone, & 2% TMC and exhibits degradation profiles with strength loss ranging from one (1) to four (4) weeks and mass loss ranging from three (3) to six (6) months depending on processing, physiological environment, and anatomical location. Additionally, Poly-Med offers Glycoprene® 7424 as a formulation exhibiting increased flexibility with a composition of 74% glycolide, 24% ε-caprolactone, and 2% TMC. Similar to Glycoprene® 935, Glycoprene® 7424 exhibits a degradation profile with strength loss ranging from two (2) to four (4) weeks and mass loss ranging from three (3) to six (6) months. These materials may be processed into extruded monofilaments, multifilaments, tubes, films, warp and weft knit meshes, electrospun fabrics, FDM 3D printed filaments & parts, and injection molded constructs. When processed in a multifilament warp knit mesh construct, our Glycoprene® 935 material exhibits increased burst strength and elongation at break compared to Ethicon’s Vicryl® mesh made from a PGLA 90% glycolide / 10% L-lactide multifilament yarn.

Figure 2: Poly-Med’s Glycoprene® and Strataprene® polymer series formulations exhibit polyaxial architectures where flexible substituents are located within the core of the polymer chain with rigid arms, creating a “nunchuck” design.

Lactoprene® Polymer Series as an Alternative to PLLA, PLGA, and PLCL polymers:

PLLA and PLGA materials may also exhibit strengths in the GPa range, although with longer degradation profiles losing strength within six (6) to twelve (12) months and mass loss ranging eighteen (18) to thirty-six (36) months depending on processing, physiological environment, and anatomical location. 100% PLLA materials have shown problematic long-term biocompatibility when processed into certain formats, most notably with the recall of Ethicon’s Panacryl® suture for orthopedic applications due to burst release of lactic acid units from high-crystalline polymer segments.

Poly-Med’s Lactoprene® bioresorbable polymers are linear block co-polymer formulations with varying ratios of lactide, ε-caprolactone, and TMC. This polymer architecture creates a segmented degradation profile that does not exhibit burst release of lactic acid that has been observed with standard PLA polymers and therefore increases a devices biocompatibility potential. Similar to the triadic design implemented into the Glycoprene® and Strataprene® bioresorbable polymer series, the Lactoprene® bioresorbable polymer series also exhibits stiffer lactide-based segments and more flexible TMC-based segments. Poly-Med’s stiffest and longest lasting lactide-based material, Lactoprene® 8812, is constituted by 88% L-lactide & 12% TMC and exhibits strength loss ranging from six (6) to twelve (12) months and mass loss ranging from eighteen (18) to thirty-six (36) months.  Poly-Med also offers a slightly more flexible formulation, Lactoprene® 8411, made of 84% L-lactide, 11% TMC, and 5% ε-caprolactone that exhibits a strength loss ranging from three (3) to nine (9) months and mass loss ranging from twelve (12) to thirty-six (36) months. Poly-Med also offers a unique, flexible lactide-based bioresorbable polymer formulation, Lactoprene® 7415, exhibiting a block co-polymer structure of 74% L-lactide, 11% ε-caprolactone, and 15% TMC. Additionally, Lactoprene® 7415 exhibits a similar degradation profile to Lactoprene® 8411 dependent on processing, physiological environment, and anatomical location. Overall, Poly-Med’s Lactoprene® bioresorbable polymer series may be used in a variety of manufacturing techniques that include but are not limited to extruded monofilaments, multifilaments, tubes, films, warp and weft knit meshes, electrospun fabrics, FDM 3D printed filaments & parts, and injection molded constructs.

Figure 3: Poly-Med’s Lactoprene® polymer series formulations exhibit linear block co-polymer architectures with segmented degradation profiles that do not exhibit burst release of lactic acid.

Strataprene® Polymer Series as Unique Elastomeric Bioresorbable Polymer Materials:

Similar to Poly-Med’s Glycoprene® bioresorbable polymer series, Strataprene® polymer formulations exhibit a polyaxial block co-polymer architecture but are elastomeric materials. Our Strataprene® 5525 material exhibits extensibility of >500% when processed into a variety of formats. This bioresorbable polymer formulation is constituted by 55% glycolide, 25% TMC, and 20% ε-caprolactone. Strataprene® 5525 exhibits a strength loss ranging from one (1) to two (2) months and mass loss ranging from six (6) to nine (9) months depending on processing, physiological environment, and anatomical location. Strataprene® 5525 may be used for extruding films, electrospinning, FDM 3D printing filaments and parts, and injection molding.

Strataprene® 3534 exhibits similar mechanical properties to Strataprene® 5525, although much more extensible at >1,000%. This bioresorbable polymer formulation is constituted by 35% ε-caprolactone, 34% L-lactide, 17% glycolide and 14% TMC. Strataprene® 3534 exhibits a strength loss ranging from one (1) to three (3) months and mass loss ranging from twelve (12) to eighteen (18) months depending on processing, physiological environment, and anatomical location. Strataprene® 3534 may also be used for coating other materials, extruding films, electrospinning, FDM 3D printing filaments and parts, and injection molding.

Bioresorbable Polymers and Manufacturing Vertically Integrated Partner:

Manufacturing bioabsorbable medical devices is challenging. 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 bioresorbable polymer manufacturers, Poly-Med produces polymer, is able to extrude this material to desired monofilament or multifilament formats, and is able process this material via warp knitting, weft knitting, or braiding processes to produce custom biomedical textiles. Beyond traditional textiles, , we can process our bioresorbable polymers into non-woven formats via electrospinning via our state-of-the-art electrospinning facility. In addition to accessing Poly-Med’s almost thirty (30) years of experience manufacturing bioresorbable polymers, partnering with Poly-Med simplifies your bioresorbable medical device manufacturing supply chain. Contact us to today begin developing your custom bioresorbable medical device product line with a trusted partner for manufacturing advanced bioresorbable medical devices or purchase off-the-shelf high-performance bioresorbable polymers!


Biomedical Textiles as Implantable Medical Devices

Biomedical Textiles Overview:

Biomedical textiles are fiber-based medical devices that can be implanted in patients to restore tissue properties, provide mechanical support, as well as facilitate the healing process for a variety of indications. Textile-based implantable medical devices include but are not limited to sutures, meshes, vascular grafts, and heart valves. Additionally, biomedical textiles may be created from synthetic or natural sources and may be non-resorbable or resorbable based on the medical device’s intended use. Biomedical textiles may be constructed via one (1) of four (4) main processing methods: 1) knitting, 2) weaving, 3) braiding, and 4) non-woven methods (i.e. electrospinning, melt-blowing, air-laying, etc.). Each of these methods offer pros and cons for developing an implantable biomedical textile-based medical device and will be explored below.

Figure 1: Cartoon representations of A) warp knitted, B) weft knitted, C) woven, D) braided, and E) non-woven textile constructs.

Knitted Biomedical Textile Constructs:

Knitted biomedical textiles are created by inter-looping yarns to form multi- dimensional structures ranging from planar fabric to custom 3D shapes.. Knitted materials may be created via warp or weft knitting processes. Warp knitted constructs have yarns spanning the length of the fabric, whereas weft knitted constructs have yarns spanning the width of the fabric (Figure 1A). Typically, warp knitted materials may be created in flat formats, whereas weft knitted materials are created in tube-like structures. Due to differences in their yarn construction patterns, warp and weft knit materials exhibit differences in mechanical properties. Warp knitted materials exhibit increased tensile strength & modulus, and lower elongation values compared to weft knit materials of similar fiber diameters and areal densities (Figure 1B). Choice of warp or weft knit constructions largely depends on the intended use for the biomedical textile application. Knitted medical devices include but are not limited to hernia meshes, grafts, and envelopes for holding other biocompatible materials.

Woven Biomedical Textile Constructs:

Woven biomedical textiles are created by interlacing of multiple sets of yarns at 90° angles using a loom (Figure 1C). Within this construct, the yarns running the length of the fabric are referred to as the warp direction, and the yarn filaments running the width of the fabric are referred to as weft direction. For 2D type structures, three (3) basic yarn patterns commonly woven are 1) plain, 2) twill, and 3) satin patterns. Plain weave patterns are constructed by passing each weft yarn over and under each warp yarn, alternating with each row. Twill weave patterns produce a fabric with a diagonal wale, created by an offset of the warp yarns. For the satin weave pattern, the weft yarns are predominantly on the front of the fabric and the interlacing weft yarns are spaced as widely as possible. Because the interlacing yarns are scattered and not a set distance, a line does not form as is the case of the twill pattern. Similar to, knitted constructs, patterns of woven materials influence the mechanical properties of the material, making certain constructions more or less appropriate given the intended use of the implantable medical device. Woven biomedical textiles are currently in use for vascular grafts as they exhibit high tensile strength in both the machine and counter-machine direction, high friction resistance, and low elongation.

Braided Biomedical Textile Constructs:

Braided biomedical textiles are created by interlacing three (3) or more yarns in diagonally overlapping patterns to form strand-like constructions (Figure 1D). These constructions include but are not limited to solid braids, hollow core braids, multi-layer braids, flat braids, bifurcated braids, and discs. Braided constructs may be customized to have a desired number yarn ends to ensure certain design features and mechanical properties are met. Common braided biomedical textiles include but are not limited to sutures, stents, shunts, and expandable medical devices.

Non-Woven Biomedical Textile Constructs:

Non-woven biomedical textiles exhibit web-like structures of entangled fibers formed via mechanical, thermal, chemical, or electrical processing methods (Figure 1E). Non-woven materials may exhibit fiber sizes on the order of extracellular matrices to act as tissue scaffolds to aid in the healing process. Currently marketed implantable biomedical textiles with non-woven nanofibers include melt-blown materials for hernia repair exhibiting diameters from –20 – 50 microns and electrospun materials used for wound matrices exhibiting fiber diameters form 0.05 – 1 microns.

Biomedical Textile Development with a Vertically Integrated Partner:

Manufacturing bioabsorbable biomedical textiles is hard. 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 biomedical textile contract manufacturers that produce advanced bioresorbable materials, Poly-Med is a vertically integrated partner that produces polymer, extrudes this material to desired monofilament or multifilament formats, and is able process this material via warp knitting, weft knitting, or braiding processes to produce a custom biomedical textile. Additionally, we can process our bioresorbable polymers into non-woven formats via electrospinning via our state-of-the-art electrospinning facility. In addition to accessing Poly-Med’s almost thirty (30) years of experience with bioresorbable polymer materials, partnering Poly-Med simplifies your bioresorbable medical device manufacturing supply chain. Contact us to today begin developing your next biomedical textile product line with a trusted partner for manufacturing advanced bioresorbable medical devices!

Polydioxanone (PDO) Polymer for Bioresorbable Medical Devices

Overview:

Polydioxanone (PDO) has gained increasing interest in the medical and pharmaceutical fields due to its unique properties, intermediate degradation, and excellent tissue response in vivo.  PDO is a synthetic, polyether-ester-based bioresorbable material that is prepared via the ring-opening polymerization of p-dioxanone (Figure 1) and is commonly used in absorbable medical devices. PDO is a colorless solid exhibiting a melting temperature (Tm) of ~110 °C, a glass transition temperature (Tg) between -10 and 0 °C, and crystallinity of ~55%. PDO-based materials are typically more flexible and weaker than homopolymers of polyglycolide (PGA) and polylactide (PLA), exhibiting a tensile modulus in the MPa range rather than the GPa range. Additionally, PDO-based materials are significantly more challenging to process than other bioresorbable materials due to PDO’s light sensitivity and propensity to depolymerize during melt processes. Despite its challenges, polydioxanone offers an ideal material choice for absorbable implants requiring functional strength loss within four (4) to six (6) weeks and full mass loss within six (6) to nine (9) months depending on processing, physiological environment, and anatomical location.

Figure 1: Polydioxanone polymer is produced from the reaction of p-dioxanone, a metal-based catalyst, and heat.

Polydioxanone (PDO) Degradation:

Like most polyester-based polymers used in manufacturing bioresorbable medical devices, PDO-based materials degrade via bulk erosion where water diffuses within the polydioxanone material and slowly hydrolyzes the polymer chains. Generally, the PDO polymer will first exhibit a decrease in average molecular weight, followed by a decrease in strength, and lastly a decrease in overall mass. Polydioxanone is degraded and metabolized into small molecules that are then excreted, circumventing the need for a surgical procedure to remove the implant. Polydioxanone is also known to be highly biocompatible in comparison to 100% PLA-based materials that exhibit significant inflammatory response due to lactic acid buildup at the implant site.

Polydioxanone (PDO)-based Bioresorbable Medical Devices:

The synthesis of polydioxanone was patented in 1977 by a team of material scientists at Ethicon, Inc. and was subsequently utilized in the first reported PDO-based medical device in 1981, the PDSTM II suture. PDSTM II suture has been offered in sizes ranging from USP 7-0 to 1 and was subsequently used in the PDS mesh also marketed by Ethicon in 1985.

After the initial suture and mesh product releases, polydioxanone was not rapid utilized outside of extrusion-based processes, due to challenges associated with processing the material and limited suppliers of bulk polymer. Over the past thirty (30) years, polydioxanone has become a more mainstream material for use in bioresorbable medical devices ranging from the Orthosorb® absorbable pin for orthopedic bone fixation, the Lapra-Ty absorbable suture clip, as well as barbed sutures.

Poly-Med offers Polydioxanone (PDO) Polymer as well PDO Conversion to Final Devices:

Poly-Med offers off-the-shelf Dioxaprene® 100M polymer granules as well as 3D printing filament for fused deposition modeling (FDM) methods. Poly-Med has deep experience with processing polydioxanone in a controlled fashion and also offers custom manufacturing to transform Dioxaprene® 100M polymer into extruded formats that include monofilament fibers, multifilament yarns, films & tubes, biomedical textile formats that include warp and weft knit meshes and braids, electrospun fabrics, and 3D printed devices. Contact us today to purchase off-the-shelf PDO polymer and 3D printing filament, or to develop your next PDO-based bioresorbable medical device in partnership with us!

Bioresorbable Polymer Foams as Medical Devices

Introduction:

Tissue Scaffolds:

Tissue engineering is a growing field that attempts to provide solutions for the regeneration of tissues that have been damaged due to disease or injury. To achieve this, tissue engineering scaffolds are regularly used to promote repair and regeneration of tissues. Scaffolds provide a three-dimensional (3D) construct and are designed to support cell infiltration, growth, differentiation, and enhance new tissue development and guide new tissue formation.  Recently, there is a growing trend in the use of resorbable polymers for the fabrication of scaffolds and other implants for various tissue engineering applications. In addition to their well-established biocompatibilities in vivo, resorbable polymers are preferred for two main reasons: (1) scaffolds fabricated from these materials provide desirable mechanical strength which, in combination with controlled degradation rates, leads to gradual reduction in mechanical strength during tissue regeneration, and (2) complete degradation of the scaffold structure over time eliminates the need for a secondary surgery for the retrieval of the implant, thus allowing faster recovery at the site of injury.

Scaffold Format: Foams

Scaffold foams have defined properties such as pore size, pore orientation, pore interconnectivity, along with pore shape.  Given mammalian cells range in diameter from ~10-100 microns, foams are an attractive and cost-effective manufacturing technique for producing scaffolds with similar properties to naturally occurring extracellular matrices (ECM)s to allow for tissue ingrowth. Scaffold structures can be created from foams may be produced through methods that include but are not limited to 1) porogen leaching, 2) phase separation, and 3) gas foaming. The proceeding section will discuss each technique in more detail.

Technical Foam Manufacturing Processes:

Porogen Leaching:

Porogen leaching is a foam manufacturing approach where 1) a mixture of polymer and porogen components is cast into a mold, 2) the mixture is dried, 3) the polymeric solvent is evaporated, and 4) the porogen is leached from the base material through washing with a solvent specific to the porogen. A variety of porogens have been used to create bioengineered foam scaffolds that include but are not limited to sodium chloride, polymers, gelatin, paraffin beads, and sugars. Porogen leaching is advantageous for creating foam scaffolds with up to 93% porosity due to 1) the ease of altering pore structure by changing the identity and concentration of the porogen constituent and 2) reproducible production of materials. Drawbacks to this approach include the requirement of high concentrations of porogen to ensure sufficient pore connectivity to maintain desired mechanical properties and the use of solvents that require post-processing for their removal to levels below established toxicity limits to allow for implantation.

Phase Separation:

Foams may also be created via thermally induced phase separation (TIPS), where a homogenous polymer solution is de-mixed through the creation of a temperature gradient to create a multi-phase system. The polymer solution is then quenched to produce a phase with a high concentration of polymer and a phase with a lower concentration of polymer. The polymer dense phase solidifies, while the polymer light phase forms crystals which may be removed to result in a porous structure (>90% porosity). Like porogen leaching, TIPS offers high control of pour morphology through altering polymer identity/concentration, temperature profiles, and porogen identities.

Gas Foaming:

Gas foaming is a production approach where gas bubbles are dispersed throughout a polymer phase material. First, solid units of the base polymer material are made using compression molding. These units are saturated with carbon dioxide (CO2) for an extended time period under high pressure to increase the solubility of CO2 within the polymer material. The pressure is then rapidly decreased to atmospheric levels, which significantly decreases the solubility of CO2 within the polymeric material creating pores. Materials with high porosity (up to 93%) and pore size up to 100 mm may be created, although control over pore dimensions remains challenging.

Case Study:

Poly-Med has developed the capability of creating bioresorbable foam constructs for tissue scaffolding applications. Using Strataprene® 3534, a poly-axial block copolymer comprised of 35% ε-caprolactone, 34% lactide, 17% glycolide, and 14% trimethylene carbonate, PMI material scientists have created bioresorbable foams with differences in porosity, overall density, and matrix surface smoothness by varying processes parameters (denoted as Type A foams and Type B foams for simplicity).  Type A foams exhibited two (2) distinct pore classes: large pores of ~10-20 microns in diameter that were distributed between the pervasive polymeric matrix and a smaller pore class ~1-3 microns in diameter distributed within the matrix scaffold. In contrast, Type B foams exhibited a singled pore class ~20-30 microns in diameter distributed evenly throughout the foam. These differences in morphology correlate to differences in density noted between Type A foams and Type B foams (Table 1).  Based on the case study shown, Poly-Med can create custom foam scaffolds that may be tuned to a particular tissue engineering application through the use of Poly-Med’s unique polymer catalog to ensure appropriate degradation timelines and through process tuning to ensure desired pore characteristics and mechanical properties are achieved.

Poly-Med, the leader in bioresorbable medical device development, is able to offer medical device development for medical-grade electrospinning, extrusion, additive manufacturing, and technical processes in a certified ISO Class 8 environment. Poly-Med facilities are certified to meet ISO: 13485:2016 standards for quality management of its design, development, and manufacturing of bioresorbable polymers, fibers, sutures, medical textiles, and biomedical products. Connect with Poly-Med today to learn more about bioresorbable foams for tissue scaffolding application by contacting sales@poly-med.com.

Figures:

Figure 1: SEM images of the interior surface of Type A foams viewed at (a) 300x and (b) 1000x magnification.
Figure 2: SEM images of the interior surface of Type B foams viewed at (a) 200x and (b) 1000x magnification.
Foam Type Density (g/mL)
Type A Foam 0.35±0.01
Type B Foam 0.27±0.01
Table 1: Density values for Type A and Type B Foams.

Poly-Med, Inc. Welcomes Governor Henry McMaster

GREENVILLE, S.C., October 13th, 2021 — Governor Henry McMaster visited with state leaders and the executive leadership team of Poly-Med, Inc.’s at its newest facility located just outside of Greenville, SC last week.  Governor McMaster’s visit was aimed at taking stock of the ever-growing biomedical industry and Poly-Med’s growing presence in the medical device industry right here in the Upstate.

In 2019, Poly-Med, Inc., the leader in bioresorbable materials and medical device development, opened a state of the art development and production facility doubling their footprint in the Upstate.  The new facility greatly expands PMI’s capabilities to offer medical device development for  medical-grade electrospinningextrusion, additive manufacturing, and technical textile processes in a certified ISO Class 8 environment. 

Governor McMaster was encouraged by the growth of the company and the technological advancements that Poly-Med has achieved in recent years of utilizing resorbable materials to expand medical device and implant functionality.  The Governor and many others at the state level are encouraging manufacturing investment in the life sciences and biomedical industries within the State. During his visit, the Governor toured Poly-Med’s facility and evaluated its innovative technologies used to produce implants that act as a natural scaffold in the body to replace damaged or diseased tissues.

Poly-Med’s President, David Shalaby, stated “Poly-Med is a solutions’ driven organization that is working on the next class of medical devices.  The expansion of our facilities demonstrates Poly-Med’s dedication to build an infrastructure for custom medical device development within South Carolina. Our focus within the specialty resorbable material field continues our long history of designing and delivering first in class products. We look forward to growing our presence in South Carolina to support our clients in their medical device design and resorbable implant needs that improve the quality of life for patients.” 

The expansion of Poly-Med’s facilities is an investment in the ever-growing life sciences community in the Southeast, particularly in South Carolina. South Carolina is home to a $12+ Billion industry with over 700 dedicated life science firms. To learn more about Poly-Med or the opening of the new facility, please contact Poly-Med.

About Poly-Med, Inc.

For the past 28 years, Poly-Med has developed first in class innovative medical implants that improve the quality of life for patients.  Poly-Med’s mission is to drive innovation in the biomedical industries that positively impact human health. 

Outreach Contact: Joey Thames

864-760-2104 joey.thames@poly-med.com

Analytical Testing for Bioabsorbable Polymer Medical Devices: In-Vitro Degradation Studies

Bioabsorbable polymers were first introduced in the 1960s and have gained traction in the use of medical devices due to their ability to be safely resorbed; thus, leading to a reduction in complications typically observed with the long-term use of foreign material in the human body. These materials are unique in that they can be tailored to a specific application or intended use through various processing techniques to alter their material and physical properties, as well as their degradation profiles. These processing techniques range from different manufacturing processes and sterilization methods to the inclusion of additives during the synthesis of the polymer or during the manufacturing process. Throughout literature, it is noted that these processing techniques can drastically alter the bioresorbable polymers’ properties and degradation profiles; thus, it is imperative that the material and physical properties of the material be captured in a physiologically relevant environment through custom in vitro degradation studies.

At Poly-Med, Inc., we offer a variety of services to characterize the properties and degradation profiles of bioabsorbable medical-grade polymers, components, and devices. These services range from creating custom biomedical solutions to performing analytical evaluations. Poly-Med’s expertise in bioabsorbable polymer analytical evaluations has allowed us to become leaders in performing custom in vitro degradation studies in simulated and controlled environments. Utilizing ASTM standards, primarily ASTM F1635 (Standard Test Method for In Vitro Degradation Testing of Hydrolytically Degradable Polymer Resins and Fabricated Forms for Surgical Implants), the degradation rates and changes in material and physical properties can be characterized to provide an understanding of how the polymer will behave in a physiologically relevant environment. Most importantly, we are able to characterize the molecular weight, strength retention, and mass loss profiles over a designated period of time to construct the degradation profiles.

PMI’s medical-grade bioabsorbable polyester-based polymers typically demonstrate strength loss prior to exhibiting complete mass loss, as depicted in Figure 1. Initially, when these types of implants are placed in an in vitro environment, the implant will interact with the surrounding water molecules leading to water absorption and penetration in the implant itself. While this process is complex, these water molecules will penetrate the implant, which will lead to the polymer chains undergoing hydrolytic degradation cleaving into smaller and smaller chains. Material properties, as well as material processing (e.g., annealing procedures, implant dimensions, etc.), can influence degradation behavior, including monomer content, molecular weight, hydrophilicity, crystallinity, phase microstructure, and thermal properties.

Figure 1: Representative degradation profile observed of bioabsorbable polyester-based polymers.

As PMI’s polyester-based polymers undergo bulk erosion, degradation initially occurs within the amorphous microdomains of the polymer (Figure 2). As the degradation process ensues, the implant will lose its molecular weight, which leads to a loss in the material’s strength. This will ultimately lead to the complete mass loss of the polymer over time, as the implant remains exposed to the in vitro environment.

Figure 2: Representative bulk erosion profile observed of bioabsorbable polyester-based polymers

As each implant displays different strength retention and mass loss profiles, in vitro degradation studies provide the ability to accurately characterize the polymer material’s response in a physiological in situ environment; as well as provide an understanding of the effects of various manufacturing processes on the materials’ strength retention and mass loss profiles.

As degradation profiles for these polymers can range from days to years, it can be necessary to characterize the material’s degradation profile along with material and physical properties at an accelerated rate. This can be accomplished by performing in vitro degradation studies at an increased temperature of 50°C compared to the standard temperature of 37°C. By elevating the study’s temperature, the strength retention and mass loss profiles are able to be evaluated and characterized in a shorter duration than compared to the real-time monitoring performed at 37°C.  When degrading at elevated temperatures, a specific polymer’s thermal properties (i.e., glass transition temperature and melting temperature) should be assessed as these properties can significantly alter degradation behavior. Despite providing a quicker timeframe in capturing the degradation profile, in vitro degradation studies should always be conducted at 37°C to ensure an accurate representation of the real-time response under physiological conditions. As degradable polymers are evaluated for new implantable devices, continuous improvement in the standardization for characterizing degradation behavior is essential. Though ASTM F1635 continues to be the go-to guide for researchers, considerations for accelerated in vitro testing and theoretical modeling may assist in establishing a more robust methodology when evaluating bioabsorbable implants for human use.

Contact us today to set up your custom in vitro degradation study!

Bioabsorbable Polymers: Poly-Med Chairs Workshop on the Use of Absorbable Polymers for Medical Devices

In late January, Poly-Med, Inc.’s Chief Technology Officer, Dr. Scott Taylor, organized and chaired a two-day virtual workshop on the use of absorbable polymers for medical devices sponsored by ASTM Committee F04 on Medical and Surgical Materials and Devices.  The ASTM International defines and sets global standards across industries; these standards are used to improve product quality, enhance health and safety, strengthen market access and trade, and build consumer confidence. Standardization is an important factor in the medical field, and being able to lead this committee gives us the platform to influence and help set the optimal standards. Poly-Med contributes using its experience with the development of medical-grade polymers, scaffolds, and devices for use in medical devices and components.

The workshop had three main areas of discussion: 1) Polymer – Device Characterization 2) Novel Polymers and Processes, and 3) Clinical / Regulatory considerations for absorbable polymers for medical devices. As absorbable polymers are designed to degrade in the body, Polymer – Device Characterization is of paramount importance in understanding the mechanism of degradation and the resulting impact on the device, as well as the impact on the surrounding environment. Industry leaders from Johnson and Johnson led this session with the discussion and presentation of in vitro models to elucidate the role of simulated use and its effect on device performance and functionality during the degradation period. When designing such models, researchers have progressed from conducting simplistic experiments (phosphate-buffered saline, body temperature (37°C), gentle agitation), to physiological relevant models that replicate not only internal conditions but use cases and physiological loading specific to the implantation environment. Speakers in this session also provided insight into human factors and how external factors from the user, could alter the outcome of device characterization. Human factor training in device deployment and tissue placement can vary based on surgical training. As we have learned firsthand at Poly-Med, simulated use models and studies lay the foundation for understanding how a material will behave in the body and provides insight into key stages of device performance and eventual resorption.

The second session, “Novel Polymers and Processes,” focused on the two emerging processing technologies of electrospinning and additive manufacturing. Electrospinning is an established methodology that can create fibrous scaffolds that closely align with native tissue topography and mechanics, as wells as size-scale. Electrospinning is a highly tunable, versatile, and commercially successful technology that is based on consistency and scalability. The use of electrospun materials has been catapulted by the ever-expanding cell therapy markets ($11 billion in global financing in 2020). Moreover, the use of these electrospun implants acts not only as delivery and retention vehicles but also as an immuno-protective membrane. By mimicking size-scale and having a high level of porosity, cellular populations can grow on these materials and allow the release of cellular-based materials and chemicals to stimulate a biological response. Additional research is continuing to understand the specific attributes of fiber quality, size, and consistency, as well as their effects on positive clinical outcomes.

Additive manufacturing, with a focus on digital light processing, is another emerging platform that aims to provide patient-specific implants with geometries and properties for peak performance by overcoming the limitations of current manufacturing processes. With digital light processing, though significant enhancements have been made regarding machine and software solutions, material solutions are quite limited. To date, material solutions are limited based on the desired mechanical properties, as digital light processing is more suited for the printing of precise parts rather than load bearing parts. Furthermore, current photoinitiators are cytotoxic due to the high quantities required for curing of the printed parts, and initial evaluations of biocompatible photoinitiators have suffered from uncontrollable swelling when placed in an in situ environment. Desirable traits of such polymer systems include not only long-term manufacturability, but also the thorough characterization of these systems through in vitro models and the complete understanding of the breakdown of products and eventual clearance from the body. At Poly-Med, we continue to perform research into this area and are dedicated to expanding the development of absorbable polymer systems that can benefit device development and human health.         

The final session of the conference presented cases of clinical translation of absorbable devices as well as the regulatory considerations for future absorbable device development. Case examples of absorbable devices spanned uses from wound care and neurological tissue repair to stenting technologies. In each of the presented clinical cases, the importance of implant design and material selection was heralded as being of top importance for successful patient outcomes. With absorbables designed to degrade, a thorough understanding of the implant performance at the clinical level was instrumental in the surgical training and education required for the adoption of absorbables. The final speaker of this session, from the FDA, presented the regulatory challenges facing absorbables. Challenges with these materials stem from their dynamic nature, unique handling control, and processing parameters required of these materials. One specific area of discussion was the evaluation of polymer molecular weight and the use of inherent viscosity in place of molecular weight characterization by gel permeation chromatography (GPC). GPC analysis includes the characterization of molecular weight (both average and number) along with polydispersity. Such information may prove vital in understanding the degradation mechanisms of absorbable materials, though the final result may be the same – a resorbed medical implant.

In summary of the workshop, Dr. Scott Taylor concluded the following: “across the globe the use of absorbable polymers in medical devices continues to grow at an exponential pace. The industry is seeing a resurgence in not only the need for devices to degrade over time to limit patient complications, but also the emerging fields of regenerative medicine and tissue engineering. This committee will continue to define the standards for such devices to ensure consistent quality and establishment of unifying standards for future absorbable material use in the medical fields.” For more information contact us here.