Customized Delivery with Resorbable Polymers

Polymeric drug delivery systems have undergone significant development in the last two decades.

Polymeric drug delivery has defined as a formulation or a device that enables the introduction of a therapeutic substance into the body.  Biodegradable and resorbable polymers make this possible choice for lot of new drug delivery systems.

Challenges of drug administration:

Administration of a therapeutic requires optimization of dosing regimens to maximize therapeutic benefits while minimizing unwanted side effects to patients. This optimization is governed by four (4) basic pharmacokinetic principles: 1) absorption, 2) distribution, 3) metabolism, and 4) excretion. For any given active pharmaceutical ingredient (API), a number of considerations must be taken into account when designing dosage regimens which include: 1) routes of administrations, 2) site of therapeutic action, 3) the necessity of maintenance doses to ensure long-term therapeutic benefit, and 4) size of the therapeutic window.

Controlled release drug delivery systems:  

Controlled release drug delivery systems have the potential to augment both the bioavailability and distribution profile of a given API. These systems have the ability to deliver APIs at a constant rate over long periods of time, resulting in decreased fluctuations in drug concentrations outside of a given APIs’ therapeutic window. In turn, this can decrease the dosing frequency for a given API and ultimately lead to increased patient compliance. The controlled release of APIs formulated for oral dosing is well-established through the use of complexation resins and coated reservoir systems. In contrast, non-oral controlled release drug delivery systems have historically been more challenging.

Parental drug delivery (e.g., intramuscular, intravenous, and subcutaneous administrations) is required for a number of APIs due to factors that include low bioavailability and a low tolerance for the chemical environments of the stomach and/or GI tract. Recent advances in excipient drug delivery techniques for parental administration have improved the ability to control a given API’s systemic delivery rate.

Electrospun materials:

Bioresorbable electrospun materials are an ideal excipient system given their ability to release APIs in a controlled manner over days rather than minutes/hours. These materials are also optimal due to their ability to act as a scaffold for large quantities and a variety of APIs while maintaining their biological activity. Bioresorbable electrospun materials can be degraded via natural metabolic processes and do not require surgical removal post-implantation.

Electrospinning is a process of manufacturing non-woven fibrous materials where a high voltage is applied to a probe connected to a polymer solution (which may contain an API). Once a sufficient amount of charge has accumulated to break the surface tension of the solution, a cone will form that allows for a liquid stream of polymer to be ejected at a continuous rate towards a spool. This material is then collected on the spool and can be used for downstream processing. Fibers produced via electrospinning exhibit diameters on the submicron scale (µm), causing these materials to have high surface area to volume ratios. Electrospun materials have successfully been produced for biomedical purposes ranging from controlled-release orally-dosed APIs, to wound healing applications.

Case study of successful preclinical long-term drug delivery strategy: Cisplatin

Various strategies have been developed for increasing the therapeutic benefits of certain APIs while decreasing their toxicity. Cisplatin is a highly toxic chemotherapeutic agent commonly used to treat a variety of different cancers. Cisplatin induces cell-death by causing non-specific DNA crosslinks to occur in not only cancer cells, but also healthy cells. This, in turn, causes both on-target regression of tumor cells, and several unwanted side effects that include nausea, kidney damage, nerve damage, heart failure, and hearing loss. IV administration of cisplatin results in high initial plasma drug levels which rapidly decrease with a half-life of roughly thirty (30) minutes. These plasma concentrations are contrasted with low tumor penetration, which limits the potential overall benefit of the therapeutic intervention. An ideal administration regimen of cisplatin would increase the tumor concentration of the API to maximize chemotherapeutic effects while simultaneously decreasing the plasma drug concentration to decrease unwanted side effects.

Preclinical studies by Shikanov, et al., 2011 illustrate this point. Using a bioresorbable polymer to control the delivery of cisplatin, the study was able to significantly improve therapeutic outcomes in a mouse model of bladder cancer while decreasing systemic exposure to the drug.

Remarkably, administration of cisplatin with the bioresorbable polymer directly into the tumor resulted in a five (5)-fold increase in the maximum tolerated dose (MTD) compared to systemic administration. In addition to increased tolerance of cisplatin, significant improvements in therapeutic outcomes and API distribution were observed. Local tumor injection of the bioresorbable excipient system resulted in 80% of subjects remaining disease-free for forty (40) days (i.e., the remainder of the study). This is in stark contrast to standard systemic administration of cisplatin which resulted in exponential tumor mass growth after seven (7) days. In line with the observed therapeutic benefits, local tumor administration of the bioresorbable excipient system resulted in drug levels at the site of administration over five-hundred (500) times higher than levels observed with systemic administration. Additionally, reverse trends were observed in systemic exposure where local tumor administration of the bioresorbable excipient system resulted in an eighty (80)-fold decrease in plasma drug levels compared to systemic administration. Together, this highlights the potential for polymer/API excipient systems to maximize exposure to the desired site of action, while simultaneously limiting systemic exposure to APIs and potentially decreasing side effects.

Resorbable polymers offered by Poly-Med, Inc. as excipients for drug delivery:

Poly-Med, Inc. (PMI), the leader in bioresorbable materials and medical device development, is vertically integrated with design, development, and manufacturing capabilities. PMI has a growing opportunity for providing materials for drug delivery via PMI’s unique Viscoprene® technology.  Electrospun materials are generated using a combination of the Viscoprene® polymer that forms a base depot for drug delivery with additional polymeric diluents/APIs. Once combined, this drug delivery system can be injected through a standard Luer-Lok needle and syringe to be administered into the desired anatomical location. Additionally, PMI offers a catalog of Viscoprene® polymers, which allows for tailoring of the release properties of the API to meet the necessary clinical treatment schedule.

PMI is able to offer medical device development for medical-grade electrospinning, extrusion, additive manufacturing, and technical processes in a certified ISO Class 8 environment. PMI 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 PMI today to acquire more information about the Viscoprene® drug delivery technology to customize the delivery of your active pharmaceutical ingredient of interest by contacting

Bioresorbable Polymer Composites as Implantable Medical Devices

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

Bioresorbable Polymer Films as Degradable Barriers

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

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!

Biomedical Textile Spotlight: Braiding Bioresorbables

At Poly-Med, Inc., we focus on the design, development, and manufacturing of polymeric bioresorbable medical components, devices, and excipients. Our in-house vertically integrated system sets us apart from other competitors and makes us the LEADER OF BIORESORBABLES. We offer a wide variety of integrated solutions, including textile manufacturing of medical-grade braids. With our vertically integrated system, we are able to modify the polymer and yarn that are used to create the technical braid, and then alter the post-processing steps of the braid to yield the desired strength and mechanical parameters.

A common braided medical device is the absorbable suture; these sutures provide temporary support of a wound until the tissue is able to withstand normal physiological stresses. Over time, hydrolysis of the suture leads to the absorption of the implant coupled with the loss of mechanical strength followed by mass loss of the suture. Sutures can be manufactured through braiding, which produces intricate constructs that are created through the intertwining of multiple filaments or yarns forming a singular construct. Producing braided medical devices, such as sutures, is a well-established technique that allows for the structure and mechanical behaviors to be tailored to a targeted application. By changing the braiding pattern and process settings such as pick count, parameters such as strength, kink resistance, and torsion control, can be adjusted to modify the material’s performance.

One of the benefits of our vertical integration system is the ability to oversee the process from polymer through finished device. With our known catalog of bioresorbable polymers, we have the ability to easily modify construct properties (strength and mass retention profiles) based on known chemistries. Additionally, we are able to perform custom extrusions to generate varying deniers, filament count, and tenacity.  Multifilaments are often used in braided sutures due to their excellent flexibility, handling properties, and greater knot strength compared to monofilaments. Additionally, coatings can be applied to braids to reduce surface roughness and tissue drag.  The manufacturing process of braiding is an ideal technique to develop bioresorbable sutures due to PMI’s ability to tailor braiding properties to meet the specific needs of medical applications. Contact us today to learn how we can help you with your next braided medical device!

Bioabsorbable Polymers: PGLA and PolyDioxanone (PDO) as Workhorse Materials for Device Development

Continuing the evolution of the bioresorbable medical device market has led to significant growth of the implantable device industry. When considering a bioabsorbable polymer to use for your specific device, many criteria should be considered based on the design requirements and desired functionality of the device’s intended use. Two (2) workhorse polymers that have endured the demand of multiple devices would be our Max-Prene® 955 and Dioxaprene® 100M. These polyester-based polymers have demonstrated their ability to support the need for the most demanding applications through their unique material properties.

Max-Prene® 955 is a fast-degrading, high strength, high stiffness polymer mainly comprised of glycolide with minor segments of  L-lactide. Attributable to its high glycolide content, Max-Prene® 955 allows for a faster crystallization than other glycolide/lactide copolymers, and permits improved processing (faster crystallizing time, higher modulus, and increased degradation profile). Our Max-Prene® 955 polymer typically exhibits strength loss in one to four weeks with complete mass loss occurring in approximately six (6) months (depending on processing format and anatomical location). The Max-Prene® 955 polymer can be processed for a variety of applications, including extruded articles, fiber extrusion (e.g., suture such as Vicryl®), textiles, molded applications, and 3D Printing.

Beyond Max-Prene® 955, Poly-Med offers its Dioxaprene® 100M (PDO linear homopolymer) that can also be processed into a variety of formats similar to applications listed above. Dioxaprene® 100M polymer has a lower initial modulus compared to Max-Prene® 955 and is best utilized for applications looking for extended strength retention, coupled with increased flexibility. PDO based-polymers, (e.g., PDS® II sutures), maintain strength for 4 – 6 weeks with complete mass loss occurring in approximately nine (9) months (depending on processing format and anatomical location).

When selecting a polymer to best fit your device’s need, consider one of the two workhorse polymers (Max-Prene® 955 or Dioxaprene® 100M), which continues to drive innovation in the bioresorbable medical device industry and contact us today to learn more!

Bioabsorbable Medical Device Manufacturing: Expectations For Working with Poly-Med, Inc.

Poly-Med is the leader in bioresorbable polymers and custom solutions. We are vertically integrated based on our ability to provide absorbable polymer, fiber, and mesh through the design and development process, and can manufacture these absorbable devices and components for any medical application.

To support our development approach and provide support to our vertically integrated business structure, Poly-Med, Inc. offers full in-house analytics. We have a vast array of in-house testing equipment that provide a quick and efficient turnaround on the assessment of our clients’ bioresorbable product properties.

There is more to Poly-Med than providing unparalleled expertise and an efficient, structured approach to custom solutions.

At Poly-Med, we try to always go beyond what is expected. All relationships, including and especially those with clients, involve expectations, and conflicts tend to occur when expectations are not met. Our goals are to make excellent impressions and exceed our clients’ basic expectations. We do so by being proactive, dependable, and understanding the importance of keeping commitments. Our clients trust us because they know we will properly develop and follow through on their strategies and support their product and their vision. In addition, we continuously deliver consistency: consistent quality, consistent results, consistent product.

By working with Poly-Med, you can expect:

  • Unparalleled expertise
  • Dependability
  • Reliability
  • Collaboration
  • Responsiveness
  • And, most importantly, we deliver the results.

If you are interested in developing a bioresorbable medical device and want a partner with experience, contact us for more information!

Biomedical Textile Specifications: A Review of FDA Guidance on Surgical Mesh Design

On March 2, 1999, the U.S. Food and Drug Administration released a guidance document entitled Guidance for the Preparation of a Premarket Notification Application for a Surgical Mesh. Now in 2018, nearly 20 years later, it is still easy to become overwhelmed with everything required to prepare a new device for submission to the FDA. Guidance documents such as this one provide recommendations for the starting points of testing new devices and help alleviate some of the guesswork around what is required and what isn’t. Fortunately, partnering with a company like Poly-Med, with over 25 years of experience in bioresorbable materials and textiles, can help further navigate these waters.

This particular guidance document covers submission guidelines for surgical meshes in a wide variety of applications where a mesh product would be used to reinforce weakened soft tissue. These include area applications in abdominal wall repair (hernia repair), suture line/staple line reinforcement, muscle flap reinforcement, gastric banding, breast reconstruction, pelvic organ prolapse, and many more. For many of these applications, the current market trend is moving toward bioresorbable solutions, providing mechanical support throughout the healing process without permanent synthetic materials in the body. Poly-Med is the leader in bioresorbable textiles and has developed bioresorbable mesh products on the market for a wide variety of applications.

The FDA’s primary interest in any device review can usually be summarized in two words: safety and efficacy. Not surprisingly at all, the guidance document first focuses on the product being safe for human use. Likewise, this is usually a best first-step to consider in product development as future product development will all hinge on the materials as being safe for implantation. With this in this focus, the FDA requires the submission to include description of all material components in the device. This includes at minimum the sources/supplier and purity. To satisfy this requirement, material suppliers can provide reference to device master files (MAF), Certificate of Analysis (CoA), and Safety Data Sheets (SDS) with materials, all of which are noted to help simplify the review process. When considering the materials, special attention should be paid to any materials, reagents, or processing aids which are considered to be potentially cytotoxic, carcinogenic, or immunogenic. Additional testing may be required for any of these materials which are used to air in processing and may remain as residuals in the final material.

The next step in safety of an implantable device is consideration of sterilization. Applications are suggested to specify the method, validations, sterility assurance level (SAL, recommended SAL of 10-6), method for monitoring sterility, and packaging used to maintain sterility. Poly-Med uses several trusted partners with experience in sterilization to coordinate offering these services to our clients. Dependent on the type of material used and the desired processing plan, bioresorbable meshes can be sterilized using irradiation, ethylene oxide, or new emerging technologies such as nitrogen dioxide1.

While many of our materials are used in devices on the market and have proven biocompatibility, it is recommended that biocompatibility testing be conducted on final manufactured, sterilized, and packaged devices, as all can influence the final reaction in the body. While some provisions are allowed for products using the exact same material specifications as another similar device on the market, the guidance generally recommends that applications include testing in accordance to ISO-10993 for Cytotoxicity, Sensitization, Irritation or Intracutaneous Reactivity, Systemic Toxicity (acute), Genotoxicity, Implantation with histology of the surrounding tissue, Hemolysis, and Pyrogenicity. Given that most bioresorbable materials will leave some mass within the body for greater than 30 days, the FDA further recommends testing for Subchronic Toxicity and Chronic Toxicity. These tests should generally be conducted according to relevant USP Class VI and ASTM standards.

When using bioresorbable materials, part of the efficacy claim of a surgical mesh is its ability to degrade over time. In alignment with this guidance, Poly-Med often performs degradation studies for each device developed, being sure to take into account material selection, processing methods, as well as sterilization. Poly-Med is fully capable of conducting in-house in vitro degradation studies in both real and accelerated environments. Accelerated time points are used to quickly identify appropriate time points for a real time study and then evaluate device functionality and specifications at pre-determined time points. For surgical mesh devices, common strength loss tests are dependent on the application, and often include tensile strength, burst strength, suture pull-out strength, and tear resistance.

Though expiration dating is required for all surgical meshes, the need is especially apparent with bioresorbable materials. Many of these materials degrade with exposure to moisture, light, and/or heat, so packaging and sterilization methods can play a critical role in the ultimate shelf-life of the product. This guidance allows for expiration dating to be continuously updated over time without the need for a new 510k submission under the scope of Good Manufacturing Practice (GMP). This allows products to quickly enter the market and then slowly increase the expiration dates of new production as the real-time stability study continues.

If you are interested in developing a bioresorbable surgical mesh and want a partner with experience, Contact us for more information!

Andrew Hargett, M.S.

1 Lambert, B., et al. (2011). AAPS PharmSciTech, 12(4), pp. 1116-1126. doi: 10.1208/s12249-011-9644-8

Electrospinning for Bioabsorbable Medical Devices: Standardization for Fiber-Based Devices

Poly-Med had the recent opportunity to present at an ASTM Workshop on the Characterization of Fiber-based Scaffolds and Devices in Manchester, NH at the Advanced Regenerative Manufacturing Institute (ARMI) The workshop was organized by ASTM International (, the National Institute of Standards and Technology (NIST), and hosted by ARMI. The workshop featured seminar discussions from academia, clinicians, and included industrial spotlights on emerging technologies and application of fiber-based scaffolds and the promise they offer for regenerative medicine and medical device applications. Attendees of the workshop were able to discuss how fiber-based scaffolds are able to mimic the mechanics, architecture, and functionality of native tissues, while providing a temporary replacement for new cellular and tissue growth. A key focus of the event was the development of fiber-based scaffold characterization techniques to ensure consistency across facilities and uniformity in construct description and categorization.

Poly-Med presented on the importance of accurate and timely measures of critical release criteria for fiber-based scaffolds. Such criteria are required to ensure that high quality, safe, effective, and consistently reliable products are provided to clinicians. Poly-Med’s extensive work on fiber-based scaffolds and device examples spanned the use of technical textiles (warp knit, weft knit, and braided constructs), as well as the innovative technologies of electrospinning and additive manufacturing. Key areas of interest at this workshop included, image-based analysis approaches reviewing periodicity, porosity (void space), and diffusivity of fiber-based constructs. Method development and release testing were discussed along with batch-to-batch variations and the importance of establishing robust specifications that can be accurately, and reproducibly, measured.

Fiber-based scaffolding continues to be an ideal platform for tissue scaffolds and medical devices, yet still requires superior characterization to be fully utilized across emerging medical therapies. If you are interested in converting your lab-based scaffold into a robust medical device, be sure to contact Poly-Med to learn about our fiber-based methods ( and our in-house electrospinning capabilities (

Seth McCullen, Ph.D.

Biomedical Textile Processing: Heat Setting Impact on Materials Properties

If you’ve ever woken up late for an important job interview or meeting, you’ve probably thrown on some clothes and looked in the mirror with horror at all of the wrinkles staring back at you. While ironing clothes is certainly not one of my favorite chores, something about the heat and steam can totally change the outfit’s look. In medical textiles, this process of heat setting is equally important…and not just to look good in the operating room!

At Poly-Med, Inc., we synthesize very unique polymers for extrusion into fibers/yarns and ultimately for knitting into specialized medical textiles. Though the material coming off of the knitting machine looks somewhat finished, the process to manufacture a useful product is often far from done. One such post-processing technique we use is known as heat setting. Though our materials are medical grade and bioresorbable, the core chemistry at work with heat setting our advanced textiles is the same as with ironing common clothing materials.

The long, polymeric chains in both synthetic clothing and our bioresorbable polymers are able to “stick” together to produce fibers by means of intermolecular forces, namely hydrogen bonds. When exposed to moisture, pressure, and/or temperature, these intermolecular bonds can break, shift, and realign to produce unwanted creases. Even without the externally added forces, internal stresses are introduced throughout processing, such as from the twisting of yarn during spinning or the bending of the yarn during knitting to produce the pattern.

To work around this and remove the internal stresses, the fabric can be heated above the Glass Transition Temperature (Tg), where amorphous regions of the polymer can easily slide around. This temperature is below the Melting Temperature (Tm) and thus does not result in a phase change of the fabric, but merely provides enough energy to break down the intermolecular forces in the amorphous region which previously formed into now undesirable positions. As the material cools back down, the intermolecular forces can stabilize into stress-free conditions for whatever configuration the fabric is currently held in. For clothing with a heavy iron on top of it, the result tends to ‘press’ out the wrinkles and flatten the fabric between the flat ironing board and iron.

It is here, in the actual processing methods, that differences arise for our unique materials. In clothing, a particularly pesky wrinkle can be conquered with the addition of steam and a little elbow grease. The addition of water easily penetrates the amorphous regions of the fibers and acts as a plasticizer or lubricant between the polymeric chains, effectively reducing the material’s Tg to allow the amorphous regions more freedom to move. When the material hydrolytically degrades, as with our bioresorbable polymers, the addition of steam isn’t such a great idea. We instead use dry heat, forced air, and even vacuum chambers to apply heat to the fabric and still avoid degradation or strength loss. Heat Setting by these means further allows us to use custom fixtures and presses to hold the fabric in place as it cools, producing flat as well as 3D fabric forms. While this does make the medical textiles look great, the process often improves function as well, improving handle-ability for downstream processing and end-use, allowing the construct to conform to a unique shape, providing dimensional stability, and also increasing temperature resistance.

Though bioresorbable polymers pose a few unique challenges for heat setting, Poly-Med is very experienced in unique solutions for both small and large scale projects. If you are interested in post-processing of medical textiles or you are working on a medical device and are interested in learning more about bioresorbable polymers, Contact us at to learn how we can advance your idea.

Andrew Hargett, M.S.