By Sean Fenske, Editor-in-Chief
 
Diagnostics have gained much greater attention from the public at large due to challenges that emerged during the COVID-19 pandemic. In addition, at-home testing is also of greater interest for wide-ranging diseases and conditions. As a result, diagnostics manufacturers are being tasked with developing more products to address this growing need.
 
One potentially problematic aspect of testing, especially within the home and when conducted by lay people, is the collection of the necessary sample to achieve an accurate diagnosis. A sample collection device must be easy to use and ensure an ample amount of the sample is obtained. It must also interface with the diagnostic portion in a simple way.
 
Paul Slowey, Ph.D., CEO of Oasis Diagnostics, is quite familiar with sample collection technologies for saliva and works with many medical device diagnostics developers to ensure a sufficient sample is obtained for their tests. His device uses Porex materials to absorb saliva that can then be tested by the person in their home or sent to a lab for analysis. In the following Q&A, Dr. Slowey addresses a number of questions around diagnostic sample collection technology and the challenges associated with it. In addition, he is joined by Aflal Rahmathullah, Ph.D., VP of Technology at Porex, Filtration Group, from Atlanta, Georgia, who guides the product and technology teams as they conceptualize and commercialize products in collaboration with customers across the globe.
 
Sean Fenske: Regarding sample collection, what types of samples are being referred to, and for what purpose are they required?
 
Paul Slowey, Ph.D.: All of our devices collect saliva specimens. However, there are lots of components within saliva. So we can collect DNA, RNA, proteins, metabolites, hormones, and drugs of abuse. We can collect cell-free fractions and, if you collect cell-free samples, you can diagnose things like lung cancer in 30 minutes. You can look at exosomes within the saliva, which is very important as well. So just about anything present in blood is present in saliva and we can collect the same thing.
 
For instance, we can look at Alzheimer’s disease biomarkers, Parkinson’s disease biomarkers, HPV, COVID-19, Lassa fever, and the Ebola virus. Many things can be detected with saliva, and we can do all of those things with the collection tools we have that use Porex’s material. In addition, we’ve also seen our devices used for other, non-invasive sample types—specifically, for self-collection for HPV and women’s health testing.
 
Aflal Rahmathullah, Ph.D.: As Paul mentioned, we see Porex materials used routinely for saliva-based diagnostic tests, such as Oasis Diagnostics’ collection device. In addition, we see similar parallels in other sample types where Porex materials can collect a specific amount of other samples, such as blood or urine.
 
Unlike collecting samples in a tube, Porex materials can add additional benefits to sample collection. For example, material solutions can filter samples as they are collected, reducing interfering molecules as well as eliminating downstream steps in the sample analysis workflow. The filtration efficiency can be optimized based on the sample type, as well as the analyte and test method.
 
Fenske: When designing a sample collection device, what are the first steps? What factors are the primary considerations?
 
Dr. Slowey: Typically, the request for an application would come from a customer. For example, we have a collaboration with a group at UCLA that needed a sample device that required two samples instead of one. Leveraging a device we already developed, we added a bifurcation unit where we split the sample into two and had two tubes to collect the saliva. One is used for RNA and the other is used for proteins. That’s the first step. They’ll tell you what they want and all the attributes they need in a saliva collection kit, and we will design something around those requirements.
 
Dr. Rahmathullah: Similarly, the request for our materials typically comes from a customer need. Often, we have solved a similar request for a different customer and can utilize our core expertise in what materials and attributes work best for certain sample types while maintaining customer confidentiality.

Fenske: Where would Porex enter the equation? How do they provide support as a key partner?
 
Dr. Slowey: If you look at our collection tools, we use the Porex materials in the sample collection kit. When we initially developed our collection devices, we worked with Porex on three primary needs. First, we needed an optimized base material for non-specific binding of sample and non-cytotoxic, biocompatible for human cavity collection. The second requirement was an optimized shape and density for rapid sample absorption and release with softness and flexibility for comfort. Third, we needed the material to have the appropriate adhesion properties to assemble plastics using glue in the final device design.
 
I’ll give you an example where the device didn’t perform and we went back to Porex to ask for help. The current material we use for our SuperSAL pure cell devices binds marijuana quite tightly, unfortunately. As a result, you can’t use it for drug testing, so we reached out to Krista Ewing at Porex. Krista and her team came up with a pad material that releases marijuana, and we were able to use that for drug testing.
 
In another example, we had a micro cell device, which is a miniature version of a product Porex provides but we wanted to be able to collect samples from babies. We liked the material, but it was too large to fit in the baby’s mouth. Porex was able to customize the material for that application.
 
Fenske: How do design considerations change for a sample collection device based on the primary user changing? For example, what’s the difference if a healthcare professional is using the device versus a patient in their home?
 
Dr. Slowey: We design the collection devices to be as simple as possible. The devices that incorporate a Porex material are already used in the home, so if they can be used in the home, they can certainly be used by a primary healthcare individual. The pad material is placed under the tongue, where the sample is quickly absorbed due to the optimization of the Porex material. It is then squeezed out into a tube, which is an equally important function of the Porex material to reduce sample loss, which is sent to the lab. The process works for either type of user.
 
Dr. Rahmathullah: Since we can customize our materials to the customer needs, we can incorporate absorption of a specific volume of sample into the device, so a home user wouldn’t need to worry about not collecting the right amount of sample. Additionally, we can add treatments to the material to assist with sample preparation, depending on the type of test that will be performed. For example, for one customer we add a cell lysis treatment so the cells can be lysed directly on the sample collection material, this eliminates the need for pipetting the cell lysis reagent, which is something that we can’t expect to happen outside of a laboratory setting.
 
Fenske: What are the most common challenges involving sample collection and how are new device designs addressing them?
 
Dr. Slowey: In terms of saliva collection, people can still get it wrong even though it’s a very simple device to use. As such, we’ve had to modify the instructions.
 
We probably went through ten versions as the instructions were reviewed by different people—nurses, healthcare practitioners, and regulatory experts. I think getting the instructions correct, with visual instructions, videos, and additional materials people can reference, was critical.
 
Dr. Rahmathullah: Materials that also support this as well; specifically, we can also include a sample adequacy indicator to identify that the collection is complete. This is typically done by incorporating a color change when the sample collector is saturated. This gives untrained users a quick visual indicator that they have collected enough sample.
 
Fenske: When companies require a sample collection device, what are the most common factors they overlook or neglect to consider for its design?
 
Dr. Slowey: We’ve done designs for companies that don’t use our specific device. One of the first comments they make is how simple they believe it is to produce a new collection tool. Typically, we’ve never gone through a development cycle without at least two iterations. We do the prototype design, and bring it into the lab for testing, but that first iteration is always going to have problems.
 
For example, with one device, when it was squeezed through an o-ring, it didn’t retain the saliva, which then went the wrong way. The compression tube has a draft (i.e., can’t resemble a cylindrical shape). If it does, the compression is too high and the saliva comes out the wrong way. Instead, a funnel-like shape would be required. In addition, a valve is required to allow pressure to escape. This is where the experience of our design engineers comes into play; they’re familiar with these important details.
 
Dr. Rahmathullah: Similarly for the materials incorporated within the device, we typically have to refine our initial prototypes before we finalize the customer solution in collaboration with our customer. Our team of expert product development engineers know how to select the right material and its properties, but if a customer doesn’t have all of the design inputs defined yet, we continue to refine our initial prototypes to achieve the desired customer output.

Fenske: Can you provide some insight as to the accuracy of the collection devices?
 
Dr. Slowey: We develop the kits to provide purified saliva samples. The companies with which we work develop and supply the diagnostic test. While they don’t use Oasis products, one example of a saliva test that I can give you is Orasure Technologies. OraQuick is available over the counter, enabling a home HIV test with oral fluid. The sensitivity is reported to be 99.7%, which is very specific.
 
Dr. Rahmathullah: We understand each component must perform the same each time in order to achieve that level of sensitivity. That is why the consistency of materials is essential to the overall accuracy of diagnostic tests. Our team designs each product to ensure that the customer targets are met not only at the design phase, but more importantly when we manufacture at scale.
 
Fenske: Do you have any additional comments you’d like to share on any aspect of what we discussed?
 
Dr. Slowey: While there are very few things you can’t detect in saliva, technology is improving to reduce that number even more. For example, most analytes present in saliva are in lower concentrations than in blood, making it more difficult to identify. However, in the last few years, we’re now able to identify those biomarkers and measure them in saliva. You can quantify those biomarkers in saliva using devices leveraging fluorescence technology rather than visual technology. On the other hand, some biomarkers appear in saliva but not in blood.
 
Cancer diagnostics represents a huge opportunity for saliva—with one drop of saliva, you can diagnose lung cancer in 30 minutes. Alzheimer’s is another focus area for saliva-based diagnostics. As the co-chair of a saliva working group that’s under the auspices of the Alzheimer’s Association, we’re dedicated to developing new saliva tests and modalities. Saliva is an ultrafiltrate of blood, so if you can find it in blood, you can find it in saliva as well.
 
Fenske: Are these tests all readily available? What does the market adoption look like?
 
Dr. Slowey: Alzheimer’s is very early. There’s enormous interest and quite a bit has been accomplished, but it’s still early.
 
Most work involves research applications, but as I mentioned, we’re working with companies that have blood-based biomarkers to validate their tests.
 
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