Technology Spotlight: Absorbable Composites for Implantable Scaffolds

As the emergence of tissue engineering and regenerative medicine fields continue to take off, Poly-Med, Inc. has long been a partner and proponent in innovative scaffold design.  With the ability to be a one-stop-shop for implantable scaffold and device development from polymer to product, Poly-Med has been able to build upon its research expertise and was recently awarded a patent by the US Patent office for its scaffold technology.  United States Patent # 10,004,833 titled “Absorbable Permeability-Modulated Barrier Composites and Applications Thereof” highlights the manufacture of a multilayered constructs comprised of varying materials for use as a scaffold in a variety of indications.  

The invention deals with an absorbable permeability modulated barrier composite that is fabricated from a multi-layered structure forming a composite to better mimic natural tissue properties.  One of the major benefits with composites is that multiple structures of different physico-chemical materials can be adjoined and form a singular construct with unique properties.  Within the invention, the composite material is constructed from a base layer that is a flexible film combined with additional reinforcement from a textile structure, and microfibrous layer using Poly-Med’s proprietary electrospinning processes.  The physico-chemically distinct layers provide unique properties whereby varying morphologies and chemistries can elicit different biological responses when implanted in the body.  With the microfibrous coating, the fibers are able to better replicate the topography of the native extacellular tissue structure.  The microfibrous layer can vary in both fiber properties (size) and thickness to provide a soft layer that can be readily infiltrated with a patient’s native cells.  Applications of this technology can range from general surgery use, neurological use, bladder replacement, musculoskeletal tissues, among others.     

As with all of Poly-Med’s technologies, the ability to tailor polymer chemistry and material selection is a key aspect of designing the right scaffold.  Poly-Med polymers are medical grade and can be uniquely tailored based on their exact composition, segmentation, and molecular properties.   With this technology (and others) varying medical-grade polymers from Glycoprene®, Lactoprene®, and Dioxaprene® offer another lever to pull in the design of scaffolds. To learn more about this exciting technology or other technologies available at Poly-Med, contact us at sales@poly-med.com.

Breakable barriers: absorbable polymer films in medical devices

At Poly-Med (PMI), we pride ourselves in being a “one-stop shop”, providing medical grade materials and processing services at our facilities. PMI is a trusted leader in the production of bioresorbable polymers suitable for our client’s needs. We have a variety of polymers that covers a wide range of physical and mechanical properties. Additionally, PMI is an expert on the processing of bioresorbable polymers via extrusion, technical textiles, electrospinning, as well as additive manufacturing processes.  

One of the key components Poly-Med specializes in is film production by either solvent processing or melt-extrusion.  Films have been extensively used as implantable medical devices as barrier applications in general surgery, wound care, and dental products.  Solvent processing of films is used for highly specialized products where heat sensitive materials can also be incorporated.  Solvent processing is able to incorporate multiple materials, layers within the final film construct, and care is often used in the full characterization of solvent processed films to ensure all residuals are removed to an acceptable level.  

Despite the advantages of solvent processing, melt-extrusion is a more industry standard for creation of film substrates.  Melt-extrusion involves the process of melting and metering polymer through a die to achieve the desired thickness and width dimensions upon quenching. Based on the material properties, downstream equipment such as roller systems are put in place to process the film appropriately.  Key components of the film extrusion lines are polymer feeders, extruder with a proper screw design screw, filtration system, die, quenching equipment, roller assembly, winder, and measurement equipment.

Film extrusion field is divided into two (2) categories: 1) cast, or flat film extrusion and 2) blown film. For the flat film extrusion, a die is used to direct the flow of melted polymer into a dimension controlled film. Several aspects need to be considered when setting the die gap distance such as polymer swelling, collector, and desired dimensions. It is critical to ensure constant and uniform flow of the polymer across the area of the die. The downstream equipment such as roller systems are used to ensure that the final product meets the client’s specifications. Typical film specification includes dimensions, texture, uniformity, and material molecular weight among others. Specifications must be clearly defined based on the final product functionality. 

At PMI, our engineers work diligently to identify the balance between process and final product characteristics.  Based on the polymer’s properties and product specifications, process parameters are developed to ensure the constant flow of the polymer and proper quenching of the final product. This ensures that the material is stable to either be used as the final component or be processed based on the client’s needs.

PMI specializes in contract manufacturing of components using medical grade polymers. With PMI’s vertically integrated structure, our diverse team of experts supports our clients from the initial phases of device conception and prototype development to manufacturing by providing in-house device development, project management, quality assurance, and analytical testing. Following process validations and regulatory clearance, PMI provides manufacturing services, inspection plans with validated test methods, packaging, and schedule deliveries to our clients worldwide. Our PMI team is committed to providing high quality products at a reasonable cost through constant process improvement to production lines. Connect with PMI today to hear more about our product offerings and design, development, and analytical capabilities! If you are interested in hearing more about how Poly- Med can help advance your idea and medical product conception, please reach out to us at sales@poly-med.com.

Medical-grade electrospinning for tissue engineering and regenerative medicine: a new tool for biomedical textiles

As the global medical device field continues to expand (currently >$330 Billion), a paradigm shift has focused on the creation of resorbable medical devices.  This movement has been driven by the desire of final device manufacturers to replace current non-degradable implants along with the application and creation of resorbable devices (and scaffolds) in the emerging fields of tissue engineering and regenerative medicine.  The fields of tissue engineering and regenerative medicine seek to replace and repair damaged tissues with a temporary (resorbable) scaffold that can allow new tissues to form within the body.  Resorbable polymers that can degrade into natural metabolites (e.g. H2O and CO2) can create this temporary scaffold and support structure through a variety of manufacturing processes.  

Beyond traditional manufacturing methodologies, processes that can produce implants that closely mimic the native properties within our tissues (skin, ligament, bone, cartilage, blood vessels) are on the forefront of improving medical device design.  By having medical devices that can replicate the appropriate architecture of the tissues they are meant to replace, innate healing mechanisms including cellular growth, development, and maturation can occur accelerating the healing process and forming new tissues. Of the manufacturing tools available at Poly-Med, Inc., electrospinning enables the use of a wide variety of resorbable materials allowing for different physical, mechanical, and degradation rates to be achieved through a unique fiber formation process.  

Electrospinning is an electrostatic fiber fabrication method, which uses electric force to draw a charged extension of a polymer solution into fiber diameters on a submicron scale. Using strong electric fields to generate submicron fibrous scaffolds, electrospinning has the capability to be used in a variety of indications ranging from fibrous coatings on implants to entire stand-alone devices or constructs.  

Fibrous materials created by electrospinning are comprised of a plurality of fibers resulting from an infinite number of fiber-fiber contacts and layers upon layers of fibers.  Engineering criteria for electrospun products revolve around fiber size, pore size, fiber orientation, intermixed fiber populations, and layered constructs comprised of different types of fibers and materials.  Based on these criteria, standard surgical mesh specifications including basis weight (areal density), thickness, and mechanical properties can easily be tuned and measured.  

Beyond control of the physical dimensions of an electrospun mesh, electrospun devices also allow for the easy incorporation of medical grade additives or active pharmaceutical ingredients (APIs).  As electrospinning does not typically require elevated temperatures, sensitive materials like APIs can easily be incorporated into the bulk fiber during the electrospinning process.  Besides inclusion of APIs inside fibers, physical adsorption is also possible as constructs often exhibit very high surface area to volume ratios.  Electrospun products can have varied porosities greater than seventy (70) percent!  

At Poly-Med, we specialize in novel processing of biomaterials and know first-hand what it takes to manufacture electrospun medical products on a commercial scale.  Beyond standard engineering practices of equipment qualification and process validation, we have been able to establish our own standards for tight manufacturing and process controls to allow highly capable medical grade electrospinning processes for desired outcomes and high quality products.

To summarize, medical-grade electrospinning provides an innovative tool for medical device development and has shown great promise in enabling new and exciting products.  With the ability to provide industrial scale electrospinning services, PMI can help you develop your next medical device! Contact us to learn how our electrospinning expertise can help you advance your next bioresorable medical device!

Poly-Med research published in current issue of In Vivo Journal

Development of Critical-size Abdominal Defects in a Rabbit Model to Mimic Mature Ventral Hernias

Abstract: Background/Aim: Mesh hernioplasty is one of the most frequently performed procedures in the United States. Abdominal rigidity and chronic inflammation, among other factors, contribute to long-term complications including chronic pain, abdominal wall stiffness and fibrosis.

Acute models do not replicate the chronic environment associated with most hernias, limiting the ability to improve products. The present study details development of a critical-size defect in rabbit abdominal wall for maturation into a chronic hernia to enable analysis of hernia repair devices in a realistic environment.

Materials and Methods: New Zealand White Rabbits were used to assess defect creation and mature hernia development through a period of 21-35 days.

Results and Conclusion: Through this study, a critical-size defect was developed based on 3-cm full-thickness incision through musculature and peritoneum followed by simple skin closure and wound maturation, which was identified as a reliable procedure for creating defects presenting typical aspects of mature hernias including hernia ring and adhesions.

Authors: Georgios Hilas, Michael Scott Taylor and Joel Corbett

For the complete article, visit http://iv.iiarjournals.org/

Bioresorbable polymers changing the med device landscape

Over the past few decades, the landscape of materials used in implantable medical devices has changed. Permanent implants have fallen out of favor due to their biocompatibility issues over the long term, and bioresorbable materials have taken their place in many different applications. Doctors prefer to avoid situations where revision surgeries are necessary, and patients are excited at the “regenerative” solutions.

What’s defined as a bioresorbable material? Polymers with the ability to break down within the body have been defined using many buzzwords including bio-absorbable, bio-degradable, and dissolvable – the list goes on.

To keep things simple, we have chosen to term these materials as bioresorbable. The bioresorption of these polymers occur either enzymatically or hydrolytically. You might recall from your biology classes that your body produces and consumes a wide variety of natural polymers such as proteins, amino acids, and polysaccharides like glucose, sucrose, etc. These polymers all undergo a process in the body that breaks them down using enzymes.

Synthetic polymers such as poly-lactides, poly-caprolactones, poly-glycolides, etc. are all primarily broken down via hydrolytic reactions. Many new types and combinations are being explored in a variety of applications. The physical properties of these polymers, such as flexibility, strength, shape and degradation rates, can all be customized through adjustments in the chemistry of the material and the way they are processed.

Once a recipe for a particular synthetic polymer has been developed, it is easy to scale up the production and have consistent reproducibility. In general, applications that require batch-to-batch uniformity and patient-to-patient implant response will find better solutions with synthetic polymers.

At Poly-Med, we specialize in the development and production of medical grade synthetic bioresorbable polymers. Our team has the capability of providing customized solutions using our portfolio of polymers. With a design process that has been refined for decades, Poly-Med produces consistent results that help innovative organizations accelerate the delivery of their products.

We welcome you to
contact us
for more information, and look forward to forming successful partnerships.

James Turner, Ph.D.

Vertically Integrated Custom Device Development & Manufacturing

Over the last 20 years, Poly-Med, Inc. has delivered superior materials to make advanced medical solutions possible, such as the world’s first fully biodegradable hernia mesh. With a formal process and methodology, Poly-Med is the critical partner for companies with a need highly creative solutions and extremely low margin for error. Customization and creativity without sacrificing quality are critical to rapid device development.

Poly-Med provides custom device development and manufacturing services involving bioresorbable polymer and fiber solutions unlike other companies that provide a limited set of material, design options, and process expertise. is expertise in absorbable polymers for medical applications. Poly-Med offers the deepest experience and widest range of customizable products to support the development of solutions based on unique polymeric material properties, as well as comprehensive support for regulatory approval enabling the quickest and most cost effective speed to market.

We leverage this knowledge and our proprietary polymers to offer customers the strongest competitive advantage possible. Flagship polymers available from our catalog include:

  • Max-Prene® Glycolide/lactide copolymers which provides the recognized performance of PGLA copolymers
  • Dioxaprene Polydioxanone polymers are utilized for their extended strength retention coupled with flexibility
  • Glycoprene® Provides short-term degradation profiles, and features a wide range of mechanical properties
  • Strataprene® Feature high compliance and elasticity, ideal for films and coatings
  • Lactoprene® Provide long-term absorption, and improved alternative to traditional PLLA due to a range of tailored formulations imparting varied degrees of stiffness and compliance

    Poly-Med maintains versatile operations, experienced in extrusion and medical textiles, as well as custom solutions such as electrospun and drug delivery formulations. As a vertically integrated partner for exploratory and feasibility prototyping, downstream design and development, all the way through manufacturing.

    Poly-Med customers have a creative partner they can trust and count on to help them bring their solutions to market. With a deep heritage in bioresorbable technologies, Poly-Med is the partner of choice for today’s demanding medical industry. We welcome you to
    contact us
    for more information, and look forward to forming successful partnerships.

    Elizabeth Elvington, M.S.

    Follow Poly-Med on Twitter (@Poly-Med) and LinkedIn (Poly-Med, Inc.)

  • Full Scale Electrospun Nonwovens: From Concept to Product

    Synthetic polymer-based textiles have been used for medical applications for decades and represent a staple production technique on par with injection molding and machining. Textiles are provided in a number of techniques, such as knits, braids, woven fabrics, monofilaments, films, and various nonwovens. For many medical applications, however, traditional textiles do not meet performance requirements. Melt blown nonwovens, for example, require heating a polymer to high temperatures which can damage the polymer chains and prevent inclusion of heat sensitive drugs. A solution to this issue, first developed in the early 1900s but which has gained considerable interest in the last several years, is a dry-spinning technique called electrospinning.

    Electrospinning (typically) involves the injection of a polymer solution into a high voltage static electric field, which draws the injection stream into fibers with very small diameters on the scale of nanometers (10-9 meters) to micrometers (10-6 meters), which is similar to human cell types such as fibroblasts. The resulting fabric can be up to 90% free volume with low pore size and high surface area. The small fiber dimensions also create unique mechanical behavior.

    Textiles created from electrospinning have potential medical applications for active and directed wound healing applications, stent grafts, surgical mesh, adhesion prevention, and tissue separation. Also, because the process is most often performed at room temperature, drugs and other heat sensitive materials can be included in the spinning solution and dispersed throughout the fibers.

    Poly-Med has been creating electrospun textiles for various medical applications for more than 10 years, and has developed the equipment and in-house expertise to meet the most stringent product demands. We have produced fabrics utilizing hazardous organic solvents such as hexafluoroisopropanol (HFIP) and many polymers including polyglycolide, polylactide, polydioxanone, polycaprolactone, and various copolymers.

    To support our customers, Poly-Med has scaled our capabilities to include tight environmental controls and significant production throughput. This coupled with our ISO 13485/9001 quality system and vertically integrated contract development and manufacturing services, gives our partners the advantage of unique materials and processes created in a compliant atmosphere.

    Let us know how our experience and capabilities can help you develop your product. Feel free to contact me or visit us at www.Poly-Med.com

    M. Scott Taylor, Ph.D.

    Advantages of a “Block Copolymer”





    Poly-Med’s bioresorbable polymers offer customized product options for our customers. Copolymers present advantages not usually seen in homopolymers. For this reason, many of the bioresorbable polymers are a copolymer type, such as PGLA. We take this advantage one step further and involve the polymer architecture to modulate the properties of a given material. For example, a material can have the same composition (example 90/10 PGLA) but if assembled in a different manner (linear vs. branched or block versus random as discussed earlier), different properties can be generated. Many of Poly-Med’s polymers utilize such architecture to provide the properties required by a customer for the given indication.




    Copolymers can also be synthesized in different manners to provide differentiation amongst block copolymers. The idea behind this method involves the placement of monomer “blocks” in specific locations throughout the polymer. For example, monomers can be placed wholly in the core of a polymer and will only provide such properties in the center of a chain versus placement of blocks throughout the polymer. The polymers:




    A-A-A-B-B-B-B-B-B-A-A-A




    and




    A-A-B-B-B-A-A-B-B-B-A-A




    A and B represent different monomers, and are both polymers of the same composition. Though, due to the construction of the polymer these two materials have different properties. Some polymers exhibit natural blocking during polymerization, e.g. some monomers tend to congregate independent of one another (This is due to differing reaction kinetics amongst monomers). To control this, many chemists use a “pre-polymer” approach to allow for a two-step polymerization which can allow for more consistent preparation.




    Poly-Med has over 500 different polymerization methods and also have chemists developing bioresorbable material a customer requires. Our more than 20 years of experience allow for confidence in the fact that a reproducible, medical grade material will be prepared to your specifications. Once transferred to manufacturing, that material will be prepared in our ISO 13485/9001 manufacturing environment.




    We look forward to helping with your bioresorbable material need. Please feel free to contact our team at (864) 328-0008,
    via email
    or visit us at Poly-Med.com






    Jason Olbrich, Ph.D. Manager, Business Development

    Bioresorbable Polymer Processing: Keys from the Field

    A wide variety of implantable medical devices are created using plastic components, which involve the use of more “traditional” polymers such as polypropylene and polyethylene terephthalate (PET) as well as advanced and tailored materials like polyetheretherkeytone (PEEK) and polyvinylidene fluoride (PVFD). A segment of the implantable device market utilizes an increasingly specialized polymer subset that is designed to degrade in the body after the functional life of the implant, known as bioresorbable polymers. Devices created from bioresorbable components include sutures, surgical mesh, staples, clips, pins, bone screws, and a host of other devices. It is important to note that bioresorbable polymers are intentionally designed for instability and are more expensive than traditional industrial polymers, making a focus on process control an even greater priority.




    A common requirement to all of these products is that raw materials (in this case polymers) need to be converted and later stored in some way to create a finished device. While each material has unique process requirements, bioresorbable polymers have very stringent needs for storage and processing to make a device functional.




    Common conversion techniques include melt processing, and implantable devices must be supplied sterile, both of which can be detrimental to the performance and storage stability of the product. Bioresorbable polymers degrade due to a number of process-induced factors, primarily including hydrolysis (caused by absorbed moisture), heat and mechanical stress (shear).




    Melt extrusion is a very common conversion technique, and is particularly useful in creating fibers, films, tubing, and nonwovens. As the name suggests, you cannot avoid heating the polymer above the melting temperature, imparting significant potential for degradation. Additionally, material is typically metered using a screw, introducing shear forces that can further damage the polymer. This is secondary to moisture, though, and we focus on drying polymers to less than 50ppm before extrusion. Dry, inert gas atmospheres are also utilized to minimize risk of moisture absorbtion for best results.




    While a device is intended to degrade in the body, packaged devices need to remain unaltered through shelf storage. For this, high barrier foil pouches with very low moisture vapor transmission rates (MVTR) are recommended, and devices need to be dried to a very low moisture level and backfilled with a dry, inert gas for a best chance at long term stability. We typically recommend foils with a metal (not metallized plastic) foil layer and total moisture within the device of at least less than 500ppm. Drying is commonly performed using active reduced pressure (vacuum), with or without heat, at well less than 1 Torr. Alternatively, low humidity desiccators may be used. It is important to note that each material and construct dries at different rates, from a few hours to several days, but all absorb moisture to an unstable level in a very short timeframe.




    Processing bioresorbable polymers can be a challenge, even to companies with a wealth of experience with engineering plastics. At Poly-Med, we have been processing these materials for almost 20 years and have built a significant capability in processing and preserving bioresorbable materials for maximum utility and stability, as well as assisting clients with building their own in-house capability. If you are designing a device with an absorbable component, let us know if you need help with material or process selection, packaging, drying, stability studies, or analytical support.




    For additional information about this topic or other Poly-Med materials and capabilities, visit our solutions page or send me an email




    M. Scott Taylor, Ph.D.

    Drying Bioresorbable Materials Appropriately

    A key concern for the use of bioresorbable materials is the presence of water or moisture within an bioresorbable device. As the majority of bioresorbable polymers degrade by hydrolytic degradation, minimizing water content is of the utmost importance for enhancing device life and maintaining functionality. In general, bioresorbable polymers degrade by bulk hydrolysis of main-chain esters. This hydrolysis occurs throughout the length of the polymeric chain, gradually reducing the chain length. Excessive moisture in absorbable products leads to change in device functionality through a reduction in polymer molecular weight, loss of strength, mass loss, and a shortened lifetime of the device. To extend the life of bioresorbable medical devices, drying is a critical parameter to enhance the shelf-life and stability of a product. In general terms, drying means the removal of relatively small amounts of water or other liquid from a solid material to reduce the content of residual liquid to an acceptably low value. Drying is usually the final step in manufacturing and the product is often ready for final packaging following drying. Drying parameters that influence the process include temperature, humidity, diffusion coefficient of material, and device features such as surface area, microporosity, and bulk mass within the vacuum oven (lot size of your device) to name a few. Drying methods include three main procedures: 1) placement of products in vacuum under reduced pressure (atmosphere), 2) use of desiccant, 3) use of heat to drive evaporation of water as well as and any combination therein. The desired drying method ultimately depends on the device configuration and the desired moisture level. Application of heat can be used to drive off moisture but can also have undesired effects on delicate and sensitive products.




    1) Vacuum Drying: placing your medical device in a reduced atmosphere environment is a well-known means to remove moisture from products. Adequate vacuum drying requires low vacuum levels to be reached and maintained (<1.5 Torr) throughout the drying cycle. This process can require extensive time periods to remove inherent moisture depending on the device configuration. Nitrogen purging is used to replace ambient air with pure N2 (dry air) removing ambient moisture and lowering the surrounding humidity of the environment; this method is almost always combined with vacuum drying as removal of ambient air and back-filling with dry air does not re-saturate your device and provides a moisture free environment;



    2) Desiccants are hygroscopic materials that induce or sustain a state of dryness in its vicinity and are used due to their non-toxic and odorless nature; common desiccants include silica gels, Zeolite, and montmorillonite clay each adsorbing upwards of 40% of their weight in water vapor at 100% humidity. Desiccants can also be placed within a device’s final packaging configuration (packaged within a Tyvek® substrate) to maintain a dry environment;




    3) Application of heat is another means to drive off excess moisture through evaporation and can take place at elevated temperature usually near or at the boiling point of water and can range from 60-100°C; though heating will drive off moisture it should not be used for devices constructed from polymers with low melting points or fine features, where heat could distort the functionality of the device; heating can also be combined with vacuum drying to accelerate the removal of moisture;




    To validate a drying cycle, moisture content in your device is quantified using the method known as Karl Fischer (KF) titration. KF is a classic titration method in analytical chemistry that uses coulometric or volumetric titration to determine trace amounts of water within a sample. KF is commonly used based on its high accuracy and precision, selectivity for water, small sample size required (>1g), and large detection range (0.01% (100 ppm) to 100%). A key parameter to be aware of with this method is the ambient temperature and humidity at which the measurement and test method takes place, as this can cause samples to rapidly adsorb moisture from the surrounding environment. As a precaution and to limit the effect of rapidly adsorbed moisture, nitrogen purge steps can also be implemented with this procedure.




    The final choice of drying parameters (length of time/ method) is determined on a case by case basis taking careful consideration of all aspects of device design including material (polymer) selection, device indication, device features, and desired shelf life. Regardless of the method chosen, each drying cycle must be validated to assure consistently reliable moisture specifications can be achieved for the particular device and packaging configuration prior to market launch. When dealing with absorbable materials, the choice of drying method can be difficult and complex as it is coupled with the sterilization method of your device, packaging configuration, and desired shelf life.




    An incorrect choice in drying parameters can potentially lead to a limited product shelf life and a limited return on investment on development expenditures. Poly-Med (www.Poly-Med.com) offers a breadth of bioresorbable polymer knowledge to fully support our clients throughout the complete lifecycle of a new medical device. To leverage our experience to help with your drying questions, feel free to contact us today.






    Seth McCullen, Ph.D.


    Email