Two recent papers from the Handa and Brisbois labs at the University of Georgia demonstrate how standardized biofilm reactors are being used to validate materials designed to simultaneously prevent infection and thrombosis on indwelling medical devices. Both studies used BST reactors as part of their in vitro testing, and together they illustrate how rigorous biofilm testing under realistic conditions helps translate novel biomaterials toward clinical use.
Study 1: Nitric Oxide-Releasing Ciprofloxacin Conjugate for Dual-Action Catheters
Parker, M. et al. (2026). Engineering Multifunctional Catheters with a Nitric Oxide-Releasing Ciprofloxacin Conjugate to Combat Thrombosis and Infection. Acta Biomaterialia. https://doi.org/10.1016/j.actbio.2026.07.063
This study investigated a novel molecule, SNAP-CIP, formed by covalently conjugating the nitric oxide donor S-nitroso-N-acetylpenicillamine (SNAP) with the broad-spectrum antibiotic ciprofloxacin (CIP). Their goal was to create a single compound that could both disperse biofilm via nitric oxide release and kill the resulting planktonic bacteria with ciprofloxacin, while also providing antithrombotic protection to the catheter surface.
The researchers incorporated SNAP-CIP into silicone rubber and tested the resulting material across a progression of increasingly realistic experimental models, from 24-hour bacterial adhesion studies, to a 72-hour biofilm biomass experiment, to a 14-day CDC Biofilm Reactor® study, and ultimately to an in vivo rabbit catheter model.
How the CDC Biofilm Reactor was used: The 14-day CDC Biofilm Reactor® experiment was the most demanding in vitro step before the animal model. The researchers used a modified version of ASTM E2562-17, running the reactor at 120 RPM with continuous media supplementation for two weeks, simulating the high-shear, nutrient-rich dynamic environment of a catheter inside a blood vessel. Coupon samples of the SR-SNAP-CIP material were mounted on the coupon holder rods alongside controls, and the reactor was run continuously for the full 14-day period.
This approach was important because short-term static biofilm assays may not fully capture the challenge a catheter surface faces in a real clinical environment. By subjecting the material to two weeks of continuous flow and media replenishment, the researchers demonstrated that the antibacterial performance of SNAP-CIP was not simply an artifact of initial surface chemistry but was sustained under conditions that more closely mimic indwelling device use. The CDC Biofilm Reactor® results showed approximately 0.86-log and 0.67-log reductions in S. aureus and E. coli respectively; meaningful reductions that supported moving the material forward to the rabbit model, where it ultimately showed an 84% reduction in thrombus area and 92% reduction in adhered S. aureus.
Study 2: Slippery Organogel Coatings on Nitric Oxide-Releasing Polymers
Martinez, I. et al. (2026). Slippery Organogel Coatings on Nitric Oxide-Releasing Polymers for Dual-Action Antibiofouling Properties. Journal of Colloid and Interface Science. https://doi.org/10.1016/j.jcis.2026.140624
This study took a different approach to the same fundamental problem: combining two passive and active antifouling mechanisms into a single medical-grade polymer coating. The passive mechanism is a slippery, self-healing organogel coating infused with silicone oil, which creates an ultra-smooth liquid interface that prevents bacteria, proteins, and platelets from adhering on contact. The active mechanism is nitric oxide release from SNAP incorporated into the underlying PVC polymer, which kills bacteria and inhibits platelet activation in the surrounding environment.
How the Drip Flow Biofilm Reactor® was used: Antibacterial efficacy under dynamic flow conditions was assessed using the BST Drip Flow Biofilm Reactor® (DFR 110-4; 4-channel, polysulfone material), following a revised version of ASTM E2647-13. Rectangular samples of PVC, PVC-SNAP, PVC-LIS (lubricant-infused only), and PVC-SNAP-LIS (the combined material) were placed in the reactor channels and subjected to a 6-hour batch phase followed by 48 hours of continuous media flow at 0.8 mL/min per channel at 37 degrees C and a 10-degree angle.
The DFR was well suited to this study because its thin-film, gravity-driven flow regime creates a high gas-transfer environment at low shear; conditions relevant to surfaces like catheter exteriors that are exposed to thin fluid films rather than turbulent bulk flow. Running all four material conditions simultaneously across the reactor's four independent channels also allowed direct side-by-side comparison of the passive-only, active-only, and combined approaches in a single experiment. The results showed that the combined PVC-SNAP-LIS material outperformed both individual mechanisms, achieving greater than 73% reduction in S. aureus and E. coli biomass accumulation; a result that was confirmed visually using confocal laser scanning microscopy with live/dead staining.
Why This Research Matters
Both studies are working toward the same clinical goal from different angles: reducing the burden of catheter-associated infections and thrombosis, which together represent one of the most persistent and costly problems in hospital care. Catheter-associated infections account for an estimated 86% to 95% of bloodstream infections in hospitalized patients, and current treatment (catheter removal and systemic antibiotics) contributes directly to the growing problem of antibiotic resistance.
What makes both of these approaches compelling is that they target biofilm before it forms and becomes resistant, rather than trying to treat an established infection. By incorporating antibiofilm and antithrombotic activity directly into the catheter material itself, both strategies eliminate the need for systemic drug administration and reduce the window of opportunity for bacterial colonization to occur in the first place.
Standardized biofilm reactor testing is a critical bridge between early-stage material development and clinical trials. By subjecting candidate materials to dynamic, continuous-flow biofilm conditions (conditions that more closely reflect what a catheter surface actually experiences when in use) researchers can generate the kind of reproducible, high-confidence data that supports regulatory submissions and eventual clinical adoption. Both of these studies demonstrate that rigorous in vitro biofilm testing, done under realistic conditions, is not just a validation step but also a fundamental part of building the scientific case for next-gen medical devices.
About the Reactors
The CDC Biofilm Reactor® and the Drip Flow Biofilm Reactor® are developed and manufactured by BioSurface Technologies Corporation in Bozeman, Montana. Both reactors are recognized in published ASTM standard test methods and are used in biofilm research laboratories worldwide.