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) https://www.armiusa.org/. The workshop was organized by ASTM International (http://www.astm.org), the National Institute of Standards and Technology (NIST) https://www.nist.gov/, 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.

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 today to learn how we can advance your idea.

Andrew Hargett, M.S.

Design Considerations for Biomedical Textiles: Fiber vs. Yarn

When terms like “yarn”, “fiber”, and “filament” are used, you might, at first, think that these terms are synonymous. In this blog, we’re going to disentangle the definitions, comb through the types, and dispel the looming cloud of uncertainty, so that you may weave the terms into your sentences with expertise.

When it comes to textiles, there is some additional nuance in the terminology, of which you might not be aware. Fibers, are threadlike strands of material that are significantly longer than they are wide, with an aspect ratio of 100:1. Fibers come in both synthetic and natural forms, ranging from polyesters to silk to cellulose (cotton). Fibers can also be divided up into filament and staple fibers. Filaments are continuous long lengths of fibers (measured in yards or meters) and staple fibers are short lengths (measured in inches). Filament fibers can come in two different forms – monofilament and multifilament – and are produced by extruding polymer through a spinneret to form either a single-strand or multiple-strand filament, respectively.

Yarns are multi-filament meaning they are comprised of a plurality of individual filaments that form a bundle. Yarns are measured in the common textile vernacular of denier, which can be defined as linear density or (mass (g)/9,000 m). Fibers are singular filaments in nature, comprised of a lone solid filament. The choice between using a monofilament or multifilament depends on the target application. For example, a monofilament will have decreased surface area and will be more rigid, compared to a similarly-sized multifilament. Multifilament-based meshes have superior drapability, and a noticeably softer texture, over monofilament-based meshes. Furthermore, your application may need to alter the filament’s denier (linear density) or tenacity (tensile strength), which we can tailor using our variety of polymers or by varying process parameters.

If you are looking to use an extruded bioresorbable fiber or textile in your next medical product, contact us at sales@poly-med.com for more information.

Poly-Med, Inc. Celebrates 25 Years of Innovation in South Carolina

Poly-Med, Inc., one of the first biotech companies creating bioresorbable polymers for use in medical and pharmaceutical devices is celebrating an important milestone in their history this year; 25 Years of Innovation in South Carolina.

Poly-Med, Inc. was founded by Dr. Shalaby W. Shalaby, considered one of the forefathers of the bioresorbable polymer industry. He was one of the lead inventors for several bioresorbable products that we still use today, notably, the Vicryl®suture.

Dr. Shalaby came to South Carolina in 1990 to teach and conduct research at Clemson University. He launched Poly-Med, Inc. in 1993, as a means to translate his research into medical therapies, as well as to mentor, teach, and sponsor former and current students’ continuing education.

Today, under Dave Shalaby, Dr. Shalaby’s son, Poly-Med, Inc. creates first-in-class transformative bioresorbable medical devices and pharmaceutical products, which have improved millions of patient’s lives. Poly-Med, a once small startup, has been built into a sustainable technology company that attracts and retains the best engineers, scientists, and collaborators from around the world. Dr. Shalaby had a vision when he started Poly-Med, Inc. in South Carolina. He enabled many employees to gain experience, share ideas, in a collaborative effort, and help lay the foundation for the next generation of bioresorbable polymers and medical devices. Under Dave Shalaby’s, leadership, Poly-Med, Inc. has been taken to the next level, and continues to support and improve on the things his father held dear, the application of research,  education, and fostering innovation..

“The work we do at Poly-Med is meaningful in so many ways. As a researcher, we have a chance to work with the most advanced materials and technologies. As a product developer, we work to create first-of-their-kind products to help solve unmet needs. As a collaborator, we get to work with people and companies around the world in a way that we could not have ever imagined. This is how we continue to grow the history of Poly-Med – taking chances, identifying (sometimes hidden) talent, and building new ideas into a meaningful reality.” – Scott Taylor, CTO.

Through continued improvement in personal and professional growth, Poly-Med, Inc. employees are ready and excited to further advance and innovate in the medtech and biotech industries and continue making strides to improve patient quality of life through the devices they manufacture.

Resorbable Ligation Device Elicits Successful Preliminary Results

Poly-Med, Inc. (PMI) is thrilled to share the success of the LigaTie®, a device designed and developed by Resorbable Devices AB in Uppsala, Sweden that utilizes one of Poly-Med’s Glycoprene® polymers. The LigaTie® device was developed by Dr. Odd Viking Höglund (http://bit.ly/innovator-LigaTie) and addresses challenges associated with ligation during surgical procedures. The device is utilized to restrict blood flow, prevent blood loss, and prevent air leaks, when used on lungs or airways. PMI supports Resorbable Devices AB in the material development of a novel, flexible, fast degrading, absorbable polymer that has been able to meet the demanding specifications of the LigaTie® device. The current product scope initially focuses on veterinary applications, and Resorbable Devices AB has seen great success with clinical results to date.

The LigaTie® has been successful in the following veterinary procedures: in vivo canine neutering, ligation of ovarian pedicles 1, 2 and spermatic cords,3 ex vivo cholecystectomies (removal of gallbladder) to seal the cystic duct,4 ex vivo sealing of lung tissue at lung biopsies,5 in vivo lung lobectomy in dogs with lung cancer,6 and a video-assisted thoracoscopic lung lobectomy (removal of lung lobe).7 The LigaTie® design is based on the concept of a cable tie, and the design allows for ligation of a single artery. The device is a flexible, unidirectional, self-locking, loop device produced from one of PMI’s Glycoprene® absorbable materials .

Permanent surgical sutures, and other non-absorbable devices (i.e., clips, cable ties, staples), may be used for ligation applications, but threaten to cause negative tissue responses, such as infection, inflammation, or chronic granulomas/scar tissue formation. On the other hand, the LigaTie® exhibits the following benefits due to the novel design and material choice: good tissue grip, easy and minimally invasive placement, which results in a reduction in surgery time (compared to suture ligation), standardized and secure locking mechanism, minimal inflammatory reactions, and acceptable responses for the mechanical performance-to-resorption profile. The preliminary results for the LigaTie® device are extremely promising and truly offer an innovative product for tissue ligation to prevent hemorrhage or leakage of air.

PMI is excited to support companies working to address challenges in the biomedical engineering and biotechnology fields. With PMI’s vertically integrated structure, they are capable of assisting clients take their ideas from exploration and investigation to final manufacturing and market, through in-house material development, analytical testing, product development, and project management. Connect with PMI today to hear more about our material offerings and design, development, and analytical capabilities! If you are interested in hearing more about how Poly- Med can help advance your idea or product, contact us today!

1 Höglund, O., et al. (2013). 27(8), pp.961-6. doi: 10.1177/0885328211431018.
2 Da Mota Costa, M., et al. (2016). BMC Res Notes, 9(245), pp. 1-6. doi: 10.1186/s13104-016-2042-2.
3 Höglund, O., et al. (2014). BMC Res Notes, 7(825), pp. 1-7. doi: 10.1186/1756-0500-7-825.
4 Tepper, S., et al. (2017). Can J Vet Res, 81(3), pp. 223-7. PMID: 28725113.
5 Nylund, A. et al. (Accepted). Vet Surg. Evaluation of a resorbable self-locking ligation device for performing peripheral lung biopsies in a caprine cadaveric model.
6 Ishigaki et al. (2017). Presentation at ACVS Surgery Summit. doi 10.1111/vsu.12710.
7 Guedes, R., et al. (2018). Surg Innov., 25(2), pp. 158-164. doi: 10.1177/1553350617751293. Link to video.

Bioabsorbable Medical Device Manufacturing: Poly-Med Approach to Product Development

Leading a medical device product development project is always exciting, especially when you are in the resorbable polymer space! One of the most significant milestones is the Design Verification and Validation stage, which requires clinical evaluation.

Answering probing questions is imperative for any medical device product that is being developed, but it becomes even more significant, and challenging, for a novel, marketable, and resorbable device/component. In fact, Poly-Med, being the leader in resorbable materials, understands the importance of this milestone for a clinical trial, and as such, has become the pioneer in developing resorbable components and devices that can perform (at a minimum) like their non-resorbable counterparts, while ensuring the novel device meets unmet market needs.

Poly-Med’s approach to a successful clinical trial, is to set up the design inputs, while planning for verification and validation testing. The biggest challenge for a clinical trial coming up for any device, including resorbables, is having design inputs that will ensure your designed medical device meets the intended uses, as well as the user needs, while still ensuring your processes can meet rigorous design inputs.

Some of the most common items that can be overlooked during the development of a medical device, that are critical for the clinical trials, really fall into the following categories:

– Unclear definition of user needs for the resorbable device

– Not capturing all performance, functional, regulatory, and safety requirements that are required due to the use of a resorbable material

– Ensuring your acceptance criteria (or final device specifications) meet the user need and performance of the device

In addition, without the resources, processes, design inputs, and plan, product development can become an iterative process, which ultimately, will cause scope, time, and going over budget. In summary, the critical task is developing new (scalable, efficient) processes that will allow you to meet your functional design inputs, while still meeting your milestones and budget.

Here is what makes Poly-Med successful during a medical device product development project:

– Resources: Design Verification testing. Without a good plan, things can swirl out of control. Planning for enough resources to keep testing under control, to ensure meeting your other milestones, is critical.

– A Design Verification Plan: Having a strong plan will ensure meeting your milestones and avoiding scope creep. Hence, why it is ideal to start thinking about how you would do Design Verification as you are defining your Design Inputs – this will aid with having a strong, successful Design Verification plan.

– A Good Team: Work ethic is the most important attribute the individuals at Poly-Med have. This allows the teams to create solutions efficiently and fast.

– A Strong Quality Team: Poly-Med’s quality team always ensures the device/component is meeting your Design Controls, which are critical for the success of the project.

If you are interested in learning how Poly-Med can take your idea and translate it into a first-in-class resorbable medical device contact us today!

Poly-Med Launches Poly-Med 3D

Poly-Med, Inc., the leader in bioresorbable solutions, announces the launch of Poly-Med 3D Printing a vertically integrated design and custom manufacturing advantage that produces specialized materials, with innovative design supported by, and in-house fused filament printing services for, the medical device industry.

Poly-Med 3D Printing enables more efficient development of bioresorbable devices for the medical world, resulting in faster development to market for prototype and ready to manufacture leading edge medical devices.

Ever since Charles Hull first proposed the three-dimensional (3D) printing process in 1984, the technology has developed rapidly and well beyond what originally seemed possible. 3D Printing and moreover, additive manufacturing, has emerged as a formidable force in the ever-expanding medical device and pharmaceutical fields. Now, 34 years since that first inspiration, the promise of additive manufacturing of absorbable medical implants, pharmaceuticals, and scaffolds for tissue replacement is a reality.

Poly-Med’s focus on bioresorbable materials and their development into first-in-class medical devices, has been developed and delivered for the medical market for the past 25 years. With the ability to provide fully traceable, medical-grade polymers and filaments for additive manufacturing, Poly-Med’s materials offer distinct advantages by their unique properties based on their composition, architecture, and desired performance. Poly-Med’s bioresorbable materials are not only guaranteed to have the best quality standards, they also provide innovative properties that yield a better printing experience, coupled with enhanced device functionality.

With over 910 polymer solutions, we are continuously developing bioresorbable materials for your device needs. If you have a device in mind that’s absorbable, Poly-Med is able to prototype it, or fully develop it, with 3D Printing Services.

For more information visit the Poly-Med 3D Printing page or contact us today.

Did you know Poly-Med, Inc. Provides Analytical Services?

At Poly-Med, analytical testing has been and continues to be a cornerstone of our key technological advancements in bioresorbable materials. In our formative years, our early developmental work utilized a vast array of in-house testing equipment to characterize, refine, and create our extensive polymer suite. As an added benefit of our years of growth and accumulation of laboratory skills and equipment, we can offer our extensive analytical capabilities to you – our clients – to support the development of your medical device and pharmaceutical products.

In polymer science, it is important to assess the structural integrity at different processing steps via inherent viscosity (IV) measurements. This information provides insight to the extent of degradation in a polymer, and can give a snapshot of the overall state of the material. Additionally, our polymers can be characterized using difference scanning calorimetry to determine key material characteristics like glass transition and melt temperatures. Our capabilities also include both gas chromatography (GC) and gel permeation chromatography (GPC) to determine residuals, polydispersity, and other molecular attributes.

We frequently extend these services to our clients both within, and independently of, our design and development projects. Poly-Med aims to be a trusted long-term partner for your product’s development – and that includes analytical testing needs. To meet the specific needs of our clients, analysis can be performed on an as-requested basis, or as part of release testing. We perform analysis according to consensus standards and develop custom test methods as needed. Customers benefit from our broad capabilities, fast turn-around time, and quality of service. Visit our analytics page here to see our full service offerings. Contact us for specific questions about our services or the development of testing protocols.

Electrospinning for Bioresorbable Medical Devices

Electrospinning Overview:

Electrospinning is a fiber production method which uses electric force to draw charged threads of a polymer solution or melt into fibers with diameters in the nano to micron size-scale. Electrospinning in currently being utilized in disciplines ranging from regenerative medicine (i.e., vascular, tendon/ligament, cardiac, neural, and wound healing), nanomedicine/drug delivery, cancer therapy, dentistry, and biosensors.

The set-up is simple and straightforward and includes three (3) main components:

1. Spinneret: A pump/polymer feed that distributes a polymer solution/melt at a controlled flow rate

2. High voltage source: Electrical force is applied to the spinneret, which accelerates the polymer solution as a jet from the spinneret tip to the collecting target

3. Collecting target: Accumulation area for fibers to build a fibrous construct, it can be designed for various applications and fiber orientation specifications (i.e., drum, blade collector, metallic plate, and array of parallel or counter electrodes)

Figure 1: Poly-Med’s advanced absorbable materials can be electrospun into nanofiber sheets (Panels A and B) that may be incorporated with an active pharmaceutical ingredient (API) of interest.

Electrospinning results in continuous fibers that can be produced to submicron architectures, and exhibit high surface area-to-volume ratios and inter-/intra porosity. The electrospinning technique also allows for control over mechanical properties, microstructure, degradation rates, and downstream cellular and tissue level responses. Combining these benefits with the advantages of bioresorbable materials and devices can yield positive patient outcomes including but not limited to:

• Eliminating the need for invasive secondary surgery intervention since the bioresorbable polymer is metabolized via physiological biochemical pathways

• Providing porous, supportive scaffolding for cell guidance, migration, and development until natural tissue replaces the implant/device

• Imitating structural tissue complexity by being able to build structures from the nano, micro, and macro-scale

• Synthetic alternative to acellular dermal matrices derived from human or animal-based tissues

Poly-Med, a leader in bioresorbable polymers, has utilized electrospinning to develop bioresorbable scaffolds and devices for improved tissue regeneration, restoration, and function. Poly-Med has the ability to provide industrial scale electrospinning services for a range of bioresorbable polymers that meet not only mechanical and degradation requirements but are produced with controlled processes in a cGMP environment.

Figure 2: Synthetic electrospun fibers (Panel B) have similar diameters and architectures to acellular dermal matrix products derived from human or animal-based tissues (Panel A) as seen in the 2000x SEM images shown above.

Poly-Med is a Vertically Integrated Bioresorbable Medical Device Manufacturing 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 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 more than 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!

Figure 3: Poly-Med is a vertically integrated manufacturing partner from polymer synthesis of advanced bioresorbable materials, to polymer processing based on an applications requirements, to a finished medical device or construct. Poly-Med’s vertical integration results in our customers getting their product to market faster, and simplifying our customer’s supply chain upon commercial launch of a product.

Biomedical Textile Constructs: Warp vs. Weft Knitting

Vertical integration at Poly-Med allows us to utilize our own unique materials for a vast array of downstream processing. We use bioresorbable polymers made in-house every day for custom applications in 3D printing, fiber extrusion, electrospinning, and more! This allows us to efficiently move a unique material from raw material processing into a fully formed device component. This vertical integration gives us a unique advantage in the medical textile industry, as we are able to manufacture custom, medical-grade textiles from raw materials to final products under one roof.

Of the many ways to produce textile products suitable for medical devices, warp knitting and weft knitting (circular) are some of the most commonly used in medical and other textile industries, including extensive use in the apparel industry. Each method offers unique benefits and final properties, so choosing the correct one for a specific medical application can be critical! At Poly-Med, we can help you decide which production method best suits your specific application.

Weft Knitting:

Weft knitting requires only a single yarn feed and produces a very simple stitch so that the created stitches interlock the yarn with itself. The result is a tubular knit fabric with very high flexibility and stretch. The single yarn input allows for production of very thin fabrics at a variety of fabric widths. For unique applications, the production of a tubular fabric can even allow for 3D constructs with minimal or no seams. One of the main benefits to weft knitting is cost. This knitting method only requires the single yarn feed, so trial runs can be conducted with minimal material input requirements and fewer processing steps to get started. Weft knitting can be used to produce very narrow fabrics, further reducing costs to trial out unique materials or applications. Processing times are generally short and are easily scaled between short, one-off trials and mass production.

Warp Knitting:

Warp knitting allows for many more customizations to the fabric materials and properties. Unlike the single yarn feed used in weft knitting, warp knitting requires individual ends to feed in across the entire width of the fabric. This requires some additional work to prepare the material for knitting, but offers more options for a custom fabric. Striping can be incorporated along the length of the fabric by mixing materials and the stitching pattern can be fully customized for each yarn input end. Unique combinations of materials and stitching patterns allow for very custom fabrics designed to meet specific attributes and mechanical properties. The resulting material is often more dimensionally stable and less prone to runs than weft-knit products.

Weft knitting and warp knitting represent only two (2) of the capabilities at Poly-Med to produce unique medical device components using bioresorbable polymers. If you are working on a medical device and are interesting in learning more about degradable polymers and how to process them, contact us to learn how we can advance your idea.