This article is sponsored by Porex. In this Voices interview, Medical Design & Outsourcing spoke with Aflal Rahmathullah, VP of Product Development and Engineering at Porex, to discuss opportunities in the use of porous materials for medical and diagnostic applications.
Medical Design & Outsourcing: In medical and diagnostic fields, the focus has traditionally been on chemistry or collection methods. How is that focus shifting toward materials themselves, and what opportunities does that create for innovation in the field?
Aflal Rahmathullah: At Porex, our view of the market is that the analytical portion of the workflow is pretty mature across chemistry and different immuno- and PCR-based assays. We believe there’s greater room for innovation in the pre-analytical workflow phase — getting people more access to testing, ensuring biological materials are stable during transport, and keeping the analyte as pure as possible to ensure high sensitivity in various detection methods. As we think about our strategy and how we interact with our customers, we see four major themes where materials are making a considerable impact.
First is sample collection. When a patient goes into a clinic or hospital, how do you collect these samples uniformly and dispense volumes suitable for analysis? Materials are key — collecting a specific, consistent amount of fluid and releasing it for analysis.
The second piece is access to testing. COVID accelerated this, but self-collection — collecting specimens quickly and consistently, even at home — has been a trend for decades. Hygiene and patient comfort are important for compliance, and materials play a big role. Another factor is how much cellular material is collected; think DNA and RNA. When someone self-collects, for example with a nasal swab, are we able to collect sufficient material so downstream testing is accurate?
A third area is biomarker isolation. In next-gen sequencing, you need access to the purest forms of proteins, DNA, and mRNA. You need sufficient amounts, but they must be of high purity. The material chosen to collect that sample must not interfere with the biomarker of interest.
The last piece is purification after the samples are collected. How do you keep those materials pure as they move into analytical techniques? At Porex, for example, we have applications ranging from stool purification to gastrointestinal PCR testing, where you’re looking at complex biomolecules and need to remove inhibitory substances before further analysis. Porex has developed materials to do that effectively.
We have additional examples, especially in point-of-care blood testing. A finger prick of blood can provide biomarkers, proteins, and metabolites. In blood, we’re seeing a trend toward separating plasma from red blood cells. The ability to get pure plasma without interference from heme is critical for improving test reliability and accuracy.
Porex has developed a novel point-of-care blood separation membrane using track-etched membrane technology. It’s showing promise in isolating more plasma than current state-of-the-art membranes while minimizing lysed blood and reducing holdup volume. That means less blood is needed for analysis — microliters instead of milliliters — with the same biomarker yield. The material is robust, easy to handle in clinical settings, and allows for easy SMD integration into a device of interest.
What aspects of porous materials do you think are overlooked in the industry, and how do Porex’s offerings help address those gaps?
Porous materials have been used for a significant amount of time — a couple of decades — and we’re seeing their adoption in medical device and diagnostic spaces continue to increase because there’s so much you can do with them. One area where we’re seeing rapid growth is the ability to incorporate functional materials within a porous scaffold matrix for targeted interactions.
We’re now getting to the point where you can say, “This is the one biomolecule I want to target. I know the functionality that targets it, but I don’t have a great way to deliver it and interact with it.” The porous nature of the material allows that functionality to be integrated within it.
For example, we’re able to incorporate a functionality called controlled pore glass (CPG) into inert polymer matrices used in the solid-phase synthesis of oligonucleotides. These oligos provide maximum surface activity during deprotection, synthesis and coupling reactions to build DNA strands. This is used routinely by our customers for the custom synthesis of DNA. Since we can embed CPG into an inert matrix, we’re able to maximize yield and reproducibility while keeping costs low.
We also incorporate surface-active groups like ion exchange resins or adsorbents such as activated carbons and zeolites. Ion exchange resins help separate biomolecules such as proteins and amino acids in blood, while adsorbents remove odorous and potentially dangerous VOCs in surgical settings.
We have products, for instance, that go into bone cement mixers. These can emit harmful VOCs and PMMA fumes, and our adsorbent materials protect both the patient and the surgeon during these procedures.
What can porous materials enable in functional devices, especially with respect to customization?
We offer a lot of flexibility. For example, we have customers who use our porous scaffold material to incorporate proprietary additives. One of our customers develops and supplies vital technologies and pathogen-protected blood components to blood centers, hospitals and ultimately patients who rely on safe blood. We collaborated with the customer to develop a custom product that helps manage their blood supply chain, to ensure patient safety during transfusions. In this particular case, we were able to remove unused active pharmaceutical ingredients (APIs) that could be harmful to a patient’s well-being.
When customers come to us for porous materials, what we’re essentially doing is controlling the ability of our material to transport fluids across a distance via capillary forces. There’s a fluid that interacts with the porous material, and we’re transporting or filtering it within the porous medium.
We describe this in terms of various functionalities in medical devices, such as filtration, wicking, diffusion or venting. We create solutions tailored by pore size, airflow, material, surface characteristics and even geometry. This customization supports applications in drug delivery systems, diagnostics, and blood management.
Take pore size, for instance. Porex can tune it across multiple length scales — from submicron-sized pores in track-etched membranes, to pores a few microns in diameter using fiber materials, polyurethane foams or particle-based polymers. We have the ability to tune properties based on our customer’s application of interest.
One example is capnography lines — CO₂ monitoring in patient settings. It’s required to remove moisture from human breath as patients breathe in and out of these tubes, as rapidly as possible, to achieve the highest sensitivity in carbon dioxide detection. Porex uses fibrous or particle-based materials that wick and transport moisture to the surface rapidly, keeping the inner capnography lines as dry as possible. At the same time, the material needs to prevent bacteria from entering the patient or contaminating the instrument. To do that, we use bacterial retentive membranes. So, in one application, we leverage porous materials to solve multiple challenges: the ability to wick away material and the ability to integrate within a tube in a capnography line.
What should teams consider about porous materials during the assembly and integration phases of the product lifecycle?
There are a few differences in porous polymers that make them unique in the assembly and integration process. When integrating porous materials, it’s important to understand the impact of die cutting and overmolding processes in producing parts with a reliably sealed edge. It’s not the same as cutting a dense polymer.
Another example is when integrating a shaped porous part into a complex assembly. It’s critical to set up qualification experiments in collaboration with the customer to validate expected risks in the design by looking at edges of specifications — ranges of airflow, pore size, and so on. Setting up good IQ, OQ and PQ protocols early on helps us look at high and low settings so we can understand the bounds of parameters that can influence performance.
As we set up design verification and validation plans, we also recommend evaluating long-term performance measures: How is this product going to perform in six months, a year, or two years? It’s important to understand those design studies early on at a component level, not just at a subcomponent level.
At Porex, we design, integrate and fully validate our porous materials into subcomponents. Think of us as a partner, not only for co-creating and manufacturing materials, but also for integration — a couple of steps upstream into subcomponents or higher-level components. Porex helps customers reduce the risk of integration and assembly failures when bringing a product to market.
During product development, what are the key considerations when working with porous materials?
We should all recognize that there isn’t one porous material that works for all applications. Porex thinks about this in two ways: key material properties of interest, and application-specific properties of interest.
From a material standpoint, it’s important to understand the range of pore characteristics — pore volume, pore size, tortuosity, mechanical and chemical properties — as well as the overarching biological interaction properties that are of interest. Even early on, we consider the method of manufacturing and reproducibility at scale. Are we making a thousand pieces or millions? Those kinds of things drive decision-making with materials, manufacturing platforms, and even manufacturing location. For instance, Porex has 11 manufacturing facilities, located throughout Asia, Europe and North America. Each facility specializes in the production of different porous technologies, such as sintered plastic, foam, bonded fiber and porous membranes. All of our manufacturing sites are ISO certified, and we offer dedicated local support regardless of location for manufacturing. Early understanding of our customer’s goals helps us make not only the best material decisions, but also the best logistical ones, bringing products to life sustainably and at scale.
Application is also an important consideration for product development. It’s crucial for us to understand early on how the materials will be used, so we can match the material properties to the task at hand. For example, we recommend different materials for integration into a drug delivery application versus a diagnostic application.
For instance, we have used porous polymers for the isolation of circulating tumor DNA in stool and saliva samples. We developed the material in conjunction with a customer, understanding the mechanical properties the polymer needed to have and the final use case. Porex was able to pick the right polymers, geometry and manufacturing platform, so we could manufacture at scale for them. It’s a successful product today.
All of this is only possible through close, collaborative partnerships between suppliers like Porex and our customers. We really encourage those deep conversations as early as possible. It’s okay to not have all the answers; development can be messy, and we understand that. As customers go through our methodical, stage-gated development process, we collaborative with them to build better products, and continue our mission of making the world safer, healthier and more productive.
For more information, visit porex.com.