What is an Assay?


Even a simple, seemingly small word such as “assay” has a lot of depth. So, what is an assay and what does it test for? The original application of assay was in the context of determining metal purity and dates back to the Middle Ages.

While an assay is still a common term for metallurgical applications, in modern science, an assay can refer to any study which quantifies an unknown. In pharmacological parlance, an assay is often a test for purity and/or potency of the active agent. In combination medical device testing and 510(k) approval, there are standard assays that are mandated for every device of a given type (e.g. the ISO 10993 tests) and customized assays specific to the device, the implant type, and desired claims.

Depending on the intended claims of your device, there are three families of assays commonly executed at Lupine Medical:

  1. Anti-thrombic: In an anti-thrombic assay, Lupine Medical is your one stop shop. We do everything from design, validation, execution and processing on many anti-thrombic assays.


  1. Antimicrobial: Antimicrobial assays are designed specific for each device type. In general, these tests look for the number of viable organisms on or around the device (or both) after the device is exposed to a bolus of bacteria or yeast. The intent here is to determine the log reduction (e.g. percent reduction) that the device produces on the microorganisms compared to an untreated control. Anti-biofilm assays are a subset of antimicrobial test that are still in the early stages of gaining FDA approval.


  1. Drug Elution: The third assay is a drug elution (or release) into any of several eluents (solutions), saline, serum (animal or human), and/or whole blood. This type of assay looks specifically at the release kinetics of the drug into the various eluents. Drug elution kinetic testing is a critical test in 510(k) submissions for medical devices that include antimicrobial agents.



Assay Specifics:

Lupine Medical has designed and validated several assays for markers of platelet activation and platelet adhesion, and can apply these tests to your device. In one such assay, we expose blood to the device surface in a Chandler Loop; a device used to simulate constant blood flow over the surface of the device. At the designated time, the devices are pulled from the loop and evaluated for the number of platelets adhered and coverage of the surface with thrombus. Lastly, the blood itself is also evaluated for markers of platelet activation using immunology assays to determine the number and percentage of activated platelets. Finally, we can also image and quantify the adhered platelets, monocytes, and leukocytes using confocal microscopy.

If you are seeking to make claims that your device offers antimicrobial or anti-biofilm properties there may already be tests that closely reproduce in vivo conditions for your device. More likely, however, is that you will need to adapt the in vitro assay to be specific to the geometry, implant environment, and simulated use of the final, finished device. Lupine can help you design and validate your antimicrobial assay to replicate the actual use of your device and meet the requirements for submission to the FDA. Typically we act as study director, spending time in the weeds so you don’t have to. We handle all the scheduling, protocol writing, and oversight of execution to ensure a complete, compliant final report is delivered.

At Lupine Medical, or drug-elution kinetic assays have been validated for several common antimicrobial agents in plasma and whole blood. We have multiple elution testing regimens that can be adapted to simulate the arterial and/or venous system, subcutaneous pockets, the peritoneal cavity, healing wounds, and skin contact. Let us customize an elution assay to your device and implant type.

Save Time:

Don’t waste time researching assay testing providers, regulation compliance and 510(k) footnotes. Partner with experts to save time so you can focus on the next device to reduce complications for patients.


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