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Adding a secondary component to a liquid coating results in new and synergistic properties. 

Liquid-infused polymers are recognized for their ability to repel foulants, making them promising for biomedical applications including catheter-associated urinary tract infections (CAUTIs). However, the impact of the quantity of free liquid layer covering the surface on protein and bacterial adhesion is not well understood. Here, we explore how the amount of free silicone liquid layer in infused silicone catheter materials influences the adhesion of bacteria and proteins relevant to CAUTIs. To alter the quantity of the free liquid layer, we either physically removed excess liquid from fully infused catheter materials or partially infused them. We then evaluated the impact on bacterial and host protein adhesion. Physical removal of the free liquid layer from the fully infused samples reduced the height of the liquid layer from 60 μm to below detection limits and silicone liquid loss into the environment by approximately 64% compared to controls, without significantly increasing the deposition of protein fibrinogen or the adhesion of the common uropathogen Enterococcus faecalis. Partially infused samples showed even greater reductions in liquid loss: samples infused to 70%–80% of their maximum capacity exhibited about an 85% decrease in liquid loss compared to fully infused controls. Notably, samples with more than 70% infusion did not show significant increases in fibrinogen or E. faecalis adhesion. These findings suggest that adjusting the levels of the free liquid layer in infused polymers can influence protein and bacterial adhesion on their surfaces. Moreover, removing the free liquid layer can effectively reduce liquid loss from these polymers while maintaining their functionality. 

Evaluating surface bacterial growth at buried interfaces can be problematic due to the difficulties associated with obtaining samples. In this work, we present a new method to detect signals from microorganisms at buried interfaces that is nondestructive and can be conducted continuously. Inspired by vascular systems in nature that permit chemical communication between the surface and underlying tissues of an organism, we created a system in which an inert carrier fluid could be introduced into an empty vascular network embedded in a polymer matrix. When a microorganism layer was grown on top, small molecules produced by the growth process would diffuse down into the carrier fluid, which could then be collected and analyzed. We used this system to nondestructively detect signals from a surface layer of Escherichia coli using conductivity, ultraviolet–visible (UV–vis) absorbance spectroscopy, and high-performance liquid chromatography (HPLC) for organic acids, methods that ranged in sensitivity, time-to-result, and cost. Carrier fluid from sample vascularized polymers with surface bacterial growth recorded significantly higher values in both conductivity and absorbance at 350 nm compared to controls with no bacteria after 24 h. HPLC analysis showed three clear peaks that varied between the samples with bacteria and the controls without. Tests tracking the change in signals over 48 h showed clear trends that matched the bacterial growth curves, demonstrating the system’s ability to monitor changes over time. A 2D finite element model of the system closely matched the experimental results, confirming the predictability of the system. Finally, tests using clinically relevant Staphylococcus aureus and Pseudomonas aeruginosa yielded differences in conductivity, absorbance, and HPLC peak areas unique to each species. This work lays the foundation for the use of vascularized polymers as an adaptive system for the continuous, nondestructive detection of surface microorganisms at buried interfaces in both industry and medicine. 

Microbial adhesion to medical devices is common for hospital-acquired infections, particularly for urinary catheters. If not properly treated these infections cause complications and exacerbate antimicrobial resistance. Catheter use elicits bladder inflammation, releasing host serum proteins, including fibrinogen (Fg), into the bladder, which deposit on the urinary catheter.Enterococcus faecalisuses Fg as a scaffold to bind and persist in the bladder despite antibiotic treatments. Inhibition of Fg–pathogen interaction significantly reduces infection. Here, we show deposited Fg is advantageous for uropathogensE. faecalis,Escherichia coli,Pseudomonas aeruginosa,K. pneumoniae,A. baumannii, andC. albicans, suggesting that targeting catheter protein deposition may reduce colonization creating an effective intervention for catheter-associated urinary tract infections (CAUTIs). In a mouse model of CAUTI, host-protein deposition was reduced, using liquid-infused silicone catheters, resulting in decreased colonization on catheters, in bladders, and dissemination in vivo. Furthermore, proteomics revealed a significant decrease in deposition of host-secreted proteins on liquid-infused catheter surfaces. Our findings suggest targeting microbial-binding scaffolds may be an effective antibiotic-sparing intervention for use against CAUTIs and other medical device infections. 

The most common bulk acoustic wave device used in biosensing applications is the quartz crystal microbalance (QCM), in which a resonant pure shear acoustic wave is excited via electrodes on both major faces of a thin AT-cut quartz plate. For biosensing, the QCM is used to detect the capture of a target by a target-capture film. The sensitivity of the QCM is typically based solely on the detection of mechanical property changes, as electrical property change detection is limited by the electrode on its sensing surface. A modification of the QCM called the lateral field excited (LFE) QCM (LFE-QCM) has been developed with a bare sensing surface as both electrodes are now on a single face of the quartz plate. Compared to the QCM, the LFE-QCM exhibits significantly higher sensitivity to both electrical and mechanical property changes. This paper presents theoretical and experimental aspects of LFE-QCMs. In particular, the presence and strength of the usual and newfound LFE-QCM modes depend on the electrical properties of the film and/or sensing environment. This work also presents examples of experimental setups for measuring the response of an LFE-QCM, followed by results of LFE-QCMs used to detect liquid electrical and mechanical properties, chemical targets, and biological targets. Finally, details are given about the attachment of various target-capture films to the LFE-QCM surface to capture biomarkers associated with diseases such as cancer.